Structural analysis of the female reptile reproductive system by micro-computed tomography and optical coherence tomography†

Volumetric data provide unprecedented structural insight to the reproductive tract and add vital anatomical context to the relationships between organs. The morphology of the female reproductive tract in non-avian reptiles varies between species, corresponding to a broad range of reproductive modes and providing valuable insight to comparative investigations of reproductive anatomy. However, reproductive studies in reptilian models, such as the brown anole studied here, have historically relied on histological methods to understand the anatomy. While these methods are highly effective for characterizing the cell types present in each organ, histological methods lose the 3D relationships between images and leave the architecture of the organ system poorly understood. We present the first comprehensive volumetric analyses of the female brown anole reproductive tract using two non-invasive, non-destructive imaging modalities: micro-computed tomography (microCT) and optical coherence tomography (OCT). Both are specialized imaging technologies that facilitate high-throughput imaging and preserve three-dimensional information. This study represents the first time that microCT has been used to study all reproductive organs in this species and the very first time that OCT has been applied to this species. We show how the non-destructive volumetric imaging provided by each modality reveals anatomical context including orientation and relationships between reproductive organs of the anole lizard. In addition to broad patterns of morphology, both imaging modalities provide the high resolution necessary to capture details and key anatomical features of each organ. We demonstrate that classic histological features can be appreciated within whole-organ architecture in volumetric imaging using microCT and OCT, providing the complementary information necessary to understand the relationships between tissues and organs in the reproductive system. This side-by-side imaging analysis using microCT and OCT allows us to evaluate the specific advantages and limitations of these two methods for the female reptile reproductive system.

The Time Trajectory of Choroid Plexus Enlargement in Multiple Sclerosis

Choroid plexus (CP) can be seen as a watchtower of the central nervous system (CNS) that actively regulates CNS homeostasis. A growing body of literature suggests that CP alterations are involved in the pathogenesis of multiple sclerosis (MS) but the underlying mechanisms remain elusive. CPs are enlarged and inflamed in relapsing-remitting (RRMS) but also in clinically isolated syndrome (CIS) and radiologically isolated syndrome (RIS) stages, far beyond MS diagnosis. Increases in the choroid plexus/total intracranial volume (CP/TIV) ratio have been robustly associated with increased lesion load, higher translocator protein (TSPO) uptake in normal-appearing white matter (NAWM) and thalami, as well as with higher annual relapse rate and disability progression in highly active RRMS individuals, but not in progressive MS. The CP/TIV ratio has only slightly been correlated with magnetic resonance imaging (MRI) findings (cortical or whole brain atrophy) and clinical outcomes (EDSS score) in progressive MS. Therefore, we suggest that plexus volumetric assessments should be mainly applied to the early disease stages of MS, whereas it should be taken into consideration with caution in progressive MS. In this review, we attempt to clarify the pathological significance of the temporal CP volume (CPV) changes in MS and highlight the pitfalls and limitations of CP volumetric analysis.

An arginine-rich nuclear localization signal (ArgiNLS) strategy for streamlined image segmentation of single-cells

High-throughput volumetric fluorescent microscopy pipelines can spatially integrate whole-brain structure and function at the foundational level of single-cells. However, conventional fluorescent protein (FP) modifications used to discriminate single-cells possess limited efficacy or are detrimental to cellular health. Here, we introduce a synthetic and non-deleterious nuclear localization signal (NLS) tag strategy, called 'Arginine-rich NLS' (ArgiNLS), that optimizes genetic labeling and downstream image segmentation of single-cells by restricting FP localization near-exclusively in the nucleus through a poly-arginine mechanism. A single N-terminal ArgiNLS tag provides modular nuclear restriction consistently across spectrally separate FP variants. ArgiNLS performance in vivo displays functional conservation across major cortical cell classes, and in response to both local and systemic brain wide AAV administration. Crucially, the high signal-to-noise ratio afforded by ArgiNLS enhances ML-automated segmentation of single-cells due to rapid classifier training and enrichment of labeled cell detection within 2D brain sections or 3D volumetric whole-brain image datasets, derived from both staining-amplified and native signal. This genetic strategy provides a simple and flexible basis for precise image segmentation of genetically labeled single-cells at scale and paired with behavioral procedures.

Feasibility and safety of a non-operative clinical strategy for radiologically diagnosed low grade anterior mesial temporal tumours in the absence of a histological diagnosis

BACKGROUND

Although resection of mesial temporal lobe lesions can be achieved with relatively low morbidity, resective surgery is not without risk. Whilst many lesions found in the anterior mesiotemporal lobe are low-grade entities, transforming and high-grade lesions have also been demonstrated. We investigate the feasibility of utilising serial quantitative volumetric imaging, to determine if a strategy of imaging surveillance can be safely employed for the management of radiologically diagnosed anterior mesial temporal low-grade tumours without a confirmed histological diagnosis.

METHODS

A retrospective case-note and radiology review design were utilised. The primary presenting symptomatology was recorded together with the efficacy of symptomatic control. Volumetric analysis of MRI images was performed using Brainlab software. Pre- and post-operative neuropsychological data were analysed.

RESULTS

35 patients were identified with a radiological diagnosis of a low-grade anterior mesial temporal lobe tumour. Of these, 29% (n = 10) underwent surgical resection. For the whole cohort, the mean tumour volume at diagnosis was 6.5cm3, with a mean volumetric expansion of 1.4% per month. A significant difference was found between the volumetric expansion rate of those that underwent surgical treatment and those that did not (4.9% per month vs 0.06% per month, p < .01). Of those cases that did not undergo surgical resection, no significant difference was seen between the initial diagnostic volume and the volume at the time of their most recent interval surveillance scan (p = .97). New onset epilepsy was significantly associated with a requirement for eventual surgical tumour resection; relative risk = 6.25, 95% CI = 1.5-25.9, p = .0114.

CONCLUSION

Where medical seizure control is adequate, we suggest that conservative management is feasible even in the absence of a confirmed histological diagnosis. However, in patients aged over 50 years with new onset epilepsy, a lower threshold for intervention should be considered.

Three-Dimensional Peri-Implant Tissue Changes in Immediately vs. Early Placed Tapered Implants Restored with Two Different Ceramic Materials-1 Year Results

BACKGROUND

A prospective multi-center randomized controlled clinical trial was performed to digitally analyze tissue volume changes in immediately and early placed implants with simultaneous bone augmentation restored with two different all-ceramic materials.

METHODS

A total of 60 patients received 60 bone-level tapered implants (BLT, Straumann AG) immediately (n = 30) or early placed, 8-10 weeks after tooth extraction, (n = 30). Implants were restored with all-ceramic single crowns fabricated out of zirconia (Lava Plus, 3M), or lithium disilicate (E.max CAD, Ivoclar Vivadent AG) bonded to titanium base abutments (Variobase for Cerec, Straumann AG). Impressions were taken at baseline (BL), 6 and 12 months, and STL data were used to define an area of interest (AOI) to analyze peri-implant volume changes and midfacial recessions.

RESULTS

For immediate placement, a mean volume loss of -5.56 mm3 (±5.83 mm3) was found at 6 months, and of -6.62 mm3 (±6.56 mm3) at 12 months. For early placement, a mean volume loss of -1.99 mm3 (±5.82 mm3) at 6 months, and of -3.7 mm3 (±5.62 mm3) at 12 months was found. The differences in volume loss at 12 months between the two implant placement protocols were significant (p = 0.005). In both groups, mean midfacial recessions of 0.48 mm (±0.52) occurred.

CONCLUSIONS

A more pronounced peri-implant volume loss can be expected 12 months after immediate implant placement compared with early placement.

Comprehensive volumetric phenotyping of the neonatal brain in Down syndrome

Down syndrome (DS) is the most common genetic cause of intellectual disability with a wide range of neurodevelopmental outcomes. To date, there have been very few in vivo neuroimaging studies of the neonatal brain in DS. In this study we used a cross-sectional sample of 493 preterm- to term-born control neonates from the developing Human Connectome Project to perform normative modeling of regional brain tissue volumes from 32 to 46 weeks postmenstrual age, accounting for sex and age variables. Deviation from the normative mean was quantified in 25 neonates with DS with postnatally confirmed karyotypes from the Early Brain Imaging in DS study. Here, we provide the first comprehensive volumetric phenotyping of the neonatal brain in DS, which is characterized by significantly reduced whole brain, cerebral white matter, and cerebellar volumes; reduced relative frontal and occipital lobar volumes, in contrast with enlarged relative temporal and parietal lobar volumes; enlarged relative deep gray matter volume (particularly the lentiform nuclei); and enlargement of the lateral ventricles, amongst other features. In future, the ability to assess phenotypic severity at the neonatal stage may help guide early interventions and, ultimately, help improve neurodevelopmental outcomes in children with DS.

Microsampling tools for collecting, processing, and storing blood at the point-of-care

In the wake of the COVID-19 global pandemic, self-administered microsampling tools have reemerged as an effective means to maintain routine healthcare assessments without inundating hospitals or clinics. Finger-stick collection of blood is easily performed at home, in the workplace, or at the point-of-care, obviating the need for a trained phlebotomist. While the initial collection of blood is facile, the diagnostic or clinical utility of the sample is dependent on how the sample is processed and stored prior to transport to an analytical laboratory. The past decade has seen incredible innovation for the development of new materials and technologies to collect low-volume samples of blood with excellent precision that operate independently of the hematocrit effect. The final application of that blood (i.e., the test to be performed) ultimately dictates the collection and storage approach as certain materials or chemical reagents can render a sample diagnostically useless. Consequently, there is not a single microsampling tool that is capable of addressing every clinical need at this time. In this review, we highlight technologies designed for patient-centric microsampling blood at the point-of-care and discuss their utility for quantitative sampling as a function of collection material and technique. In addition to surveying methods for collecting and storing whole blood, we emphasize the need for direct separation of the cellular and liquid components of blood to produce cell-free plasma to expand clinical utility. Integrating advanced functionality while maintaining simple user operation presents a viable means of revolutionizing self-administered microsampling, establishing new avenues for innovation in materials science, and expanding access to healthcare.

Integrated response analysis of pediatric low-grade gliomas during and after targeted therapy treatment

Background

Pediatric low-grade gliomas (pLGGs) are the most common central nervous system tumor in children, characterized by RAS/MAPK pathway driver alterations. Genomic advances have facilitated the use of molecular targeted therapies, however, their long-term impact on tumor behavior remains critically unanswered.

Methods

We performed an IRB-approved, retrospective chart and imaging review of pLGGs treated with off-label targeted therapy at Dana-Farber/Boston Children's from 2010 to 2020. Response analysis was performed for BRAFV600E and BRAF fusion/duplication-driven pLGG subsets.

Results

Fifty-five patients were identified (dabrafenib n = 15, everolimus n = 26, trametinib n = 11, and vemurafenib n = 3). Median duration of targeted therapy was 9.48 months (0.12-58.44). The 1-year, 3-year, and 5-year EFS from targeted therapy initiation were 62.1%, 38.2%, and 31.8%, respectively. Mean volumetric change for BRAFV600E mutated pLGG on BRAF inhibitors was -54.11%; median time to best volumetric response was 8.28 months with 9 of 12 (75%) objective RAPNO responses. Median time to largest volume post-treatment was 2.86 months (+13.49%); mean volume by the last follow-up was -14.02%. Mean volumetric change for BRAF fusion/duplication pLGG on trametinib was +7.34%; median time to best volumetric response was 6.71 months with 3 of 7 (43%) objective RAPNO responses. Median time to largest volume post-treatment was 2.38 months (+71.86%); mean volume by the last follow-up was +39.41%.

Conclusions

Our integrated analysis suggests variability in response by pLGG molecular subgroup and targeted therapy, as well as the transience of some tumor growth following targeted therapy cessation.

New Device to Measure Cross-Sectional Areas and Segmental Volumes of Objects and Limbs

Purpose

High accuracy volume measurements have important implications in different medical and non-medical situations. All methods used to date have challenges to achieve a usable clinical accuracy. Moreover, current methods have limitations to measure segmental volumes. We developed a new device that is able to measure a continuous profile of the cross-sectional areas along an object. Herewith the total volume of an object or any part of it are correspondingly determined.

Methods

The Peracutus Aqua Meth (PAM) generates continuous profiles of cross-sectional areas. Water is pumped in or out of a measuring unit at a nearly fixed flow rate and the speed of the water level (dh/dt) is measured continuously using a pressure sensor at the bottom. The change of the water level is a measure for the cross-sectional area of an object at any height. Signal processing is required to obtain valuable measurements. Three static objects and an arm of a test object were measured to demonstrate the accuracy and repeatability of the new device.

Results

Cross-sectional areas of a PVC pipe obtained with the PAM and with a caliper were compared. The differences between the two methods were less than 1.3%. Volume measurements of two mannequin arms show standard deviations of 0.37% and 0.34%, respectively, whereas the standard deviation of the volume measurement of a genuine arm was only 1.07%. These figures surpass reported clinical accuracy.

Conclusion

The new device demonstrates that determining the cross-section and its volumes of objects is possible in an accurate, reliable, and objective way. The results show that segmental volume measurements of human limbs are possible. Application in clinical and non-clinical situations seems meaningful.

Study on Volumetric, Compressibility and Viscometric Behavior of Cationic Surfactants (CTAB and DTAB) in Aqueous Glycyl Dipeptide: A Thermo-Acoustic Approach

This study aims to understand how glycyl dipeptide affected the compressibility, volumetric behavior and viscometric behavior of the cationic surfactants CTAB (Cetyltrimethylammonium bromide) and DTAB (dodecyltrimethylammonium bromide). Information on solute-solute, solute-solvent, and solvent-solvent interactions has been inferred using the quantification of density (ρ), speed of sound (u) and viscosity in aqueous media containing glycyl dipeptide in the temperature range 293.15-313.15 K at an interval of 5 K. The data from the aforementioned research have been used to enumerate numerous volumetric and compressibility metrics that aid in the collection of information about the interactional behavior of the system under consideration. The study suggests that CTAB interacts strongly compared to DTAB with dipeptide, and it also significantly dehydrates glycyl dipeptide. The difference in water-water interactions caused by the loss of hydrophobic hydration of the surfactant molecules upon the addition of cationic surfactants may be the cause of the variation in determined parameters with surfactant concentration. Consideration of the structural rearrangement of molecules that may occur in the system has been used to explain the results of viscosity and computed factors related to viscosity. The patterns of competitive intermolecular interactions in the ternary (dipeptide + water + surfactant) system have been used to analyze the trends of all the parameters. The study may be helpful to understand the stability and structural changes in protein-surfactant systems mediated through various interactions that may be present in the system.

Spatial-Temporal Speckle Variance in the En-Face View as a Contrast for Optical Coherence Tomography Angiography (OCTA)

Optical Coherence Tomography (OCT) is an adaptable depth-resolved imaging modality capable of creating a non-invasive 'digital biopsy' of the eye. One of the latest advances in OCT is optical coherence tomography angiography (OCTA), which uses the speckle variance or phase change in the signal to differentiate static tissue from blood flow. Unlike fluorescein angiography (FA), OCTA is contrast free and depth resolved. By combining high-density scan patterns and image processing algorithms, both morphometric and functional data can be extracted into a depth-resolved vascular map of the retina. The algorithm that we explored takes advantage of the temporal-spatial relationship of the speckle variance to improve the contrast of the vessels in the en-face OCT with a single frame. It also does not require the computationally inefficient decorrelation of multiple A-scans to detect vasculature, as used in conventional OCTA analysis. Furthermore, the spatial temporal OCTA (ST-OCTA) methodology tested offers the potential for post hoc analysis to improve the depth-resolved contrast of specific ocular structures, such as blood vessels, with the capability of using only a single frame for efficient screening of large sample volumes, and additional enhancement by processing with choice of frame averaging methods. Applications of this method in pre-clinical studies suggest that the OCTA algorithm and spatial temporal methodology reported here can be employed to investigate microvascularization and blood flow in the retina, and possibly other compartments of the eye.

Optimized Photoclick (Bio)Resins for Fast Volumetric Bioprinting

Volumetric printing (VP) is a light-mediated technique enabling printing of complex, low-defect 3D objects within seconds, overcoming major drawbacks of layer-by-layer additive manufacturing. An optimized photoresin is presented for VP in the presence of cells (volumetric bioprinting) based on fast thiol-ene step-growth photoclick crosslinking. Gelatin-norbornene (Gel-NB) photoresin shows superior performance, both in physicochemical and biocompatibility aspects, compared to (meth-)acryloyl resins. The extremely efficient thiol-norbornene reaction produces the fastest VP reported to date (≈10 s), with significantly lower polymer content, degree of substitution (DS), and radical species, making it more suitable for cell encapsulation. This approach enables the generation of cellular free-form constructs with excellent cell viability (≈100%) and tissue maturation potential, demonstrated by development of contractile myotubes. Varying the DS, polymer content, thiol-ene ratio, and thiolated crosslinker allows fine-tuning of mechanical properties over a broad stiffness range (≈40 Pa to ≈15 kPa). These properties are achieved through fast and scalable methods for producing Gel-NB with inexpensive, off-the-shelf reagents that can help establish it as the gold standard for light-mediated biofabrication techniques. With potential applications from high-throughput bioprinting of tissue models to soft robotics and regenerative medicine, this work paves the way for exploitation of VPs unprecedented capabilities.

Non-coplanar volumetric modulated arc therapy for locoregional radiotherapy of left-sided breast cancer including internal mammary nodes

Background

Non-coplanar volumetric modulated arc therapy (ncVMAT) is proposed to reduce toxicity in heart and lungs for locoregional radiotherapy of left-sided breast cancer, including internal mammary nodes (IMN).

Patients and methods

This retrospective study included 10 patients with left-sided breast cancer who underwent locoregional radiotherapy after breast-conserving surgery. For each patient, the ncVMAT plan was designed with four partial arcs comprising two coplanar arcs and two non-coplanar arcs, with a couch rotating to 90°. The prescribed dose was normalized to cover 95% of planning target volume (PTV), with 50 Gy delivered in 25 fractions. For each ncVMAT plan, dosimetric parameters were compared with the coplanar volumetric modulated arc therapy (coV-MAT) plan.

Results

T here were improvements in conformity index, homogeneity index and V₅₅ of total target volume (PTVall) comparing ncVMAT to coVMAT (p < 0.001). Among the organs at risk, the average V₃₀, V₂₀, V₁₀, V₅, and mean dose (D_mean) of the heart decreased significantly (p < 0.001). Furthermore, ncVMAT significantly reduced the mean V₂₀, V₁₀, V₅, and D_mean of left lung and the mean V₁₀ and V₅ and D_mean of contralateral lung (p < 0.001). An improved sparing of the left anterior descending coronary artery and right breast were also observed with ncVMAT (p < 0.001).

Conclusions

Compared to coVMAT, ncVMAT provides improved conformity and homogeneity of whole P TV, better dose sparing of the heart, bilateral lungs, left anterior descending coronary artery (LAD), and right breast for locoregional radiotherapy of left-sided breast cancer with IMN, potentially reducing the risk of normal tissue damage.

Impact of the Extent of Microsurgical Resection in Sphenopetro-clival Meningiomas Trough a Multistaged Approach: A Volumetric Analysis

Objective  Sphenopetroclival meningiomas (SPCMs) represent a challenge for surgical treatment. The authors used an objective volumetric analysis to assess the effect of the grade of resection and different surgical strategies that may affect the outcome of this tumors. Methods  Over a period of 4 years, patients with SPCMs were treated using a middle versus posterior fossa approach, or a two-stage surgery combining both approaches, based on the tumor location in relation to the petrous ridge and tumor volume. Retrospectively, all cases were analyzed with regard to tumor volume, extent of resection (EOR), functional outcome, and complications. Results  Twenty-seven patients with SPCMs met the inclusion criteria, and the mean follow-up was 24.8 months. Eleven patients underwent a two-stage surgery, while 16 patients had their SPCMs resected via a single craniotomy. Mean EOR was 87.6% and gross total resection was achieved in 48% of patients. Patients with greater EOR had better functional outcomes ( r  = 0.81, p  < 0.01). Greater EOR was not accompanied by a significant increase in surgical complications. There was a trend toward lower postoperative volumes and better EOR with our two-stage approach (2.2 vs. 3.2 cm ³ , p  = 0.09; and 94.1 vs. 91.2%, p  = 0.49, respectively), without an increase in the rate of complications (18.7 vs. 18.2%, p  = 0.5). Conclusion  Staging of the surgical resection of larger tumors may lead to greater EOR, and this strategy should be considered for larger tumors.

Evaluation of chemotherapy preparation processes: Volumetric method reliability and gravimetric method utility within 5 US hospitals

DISCLAIMER

In an effort to expedite the publication of articles , AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

The primary aim of this study was to investigate the accuracy of the volumetric method for intravenous (IV) preparations and explore the utility of gravimetric methods in the medication preparation process within multiple institutions. Secondary outcomes of this study were syringe size percent variations and impact on drug expenditures.

METHODS

A prospective, noninterventional, multisite study was conducted between March 2015 and December 2016 to generate baseline estimates of accuracy and precision in the volumetric medication preparation process. Five hospitals in the United States were recruited for study participation. During the data collection process, technicians were required to measure the syringe at 3 different points: when the new empty syringe was connected to a closed-system transfer device (CSTD), when the filled syringe containing the prepared dose of medication was connected to a CSTD, and when the used syringe with residual medication was connected to a CSTD. The actual dose of drug dispensed (in mg) was divided by the specific gravity of the medication to determine the actual volume of medication dispensed.

RESULTS

A total of 4,443 compounded sterile products representing 60 medications across 5 hospitals were eligible for the study. Of the evaluated preparations, 91.92% were within 5% of the prescribed dose and 96.56% were within 10% of the prescribed dose. The outliers ranged from -144.10% to 233.72%.

CONCLUSION

The potential for significant over- and undertreatment of an individual patient receiving IV chemotherapy exists, indicating the need for an additional measurement method, such as real-time gravimetric verification, to ensure an accurate dose is administered to every patient.

Three-Dimensional Volumetric Measurement of Endolymphatic Hydrops in Meniere's Disease

Objective: We used volumetric three-dimensional (3D) analysis to quantitatively evaluate the extent of endolymphatic hydrops (EH) in the entire inner ear. We tested for correlations between the planimetric and volumetric measurements, to identify their advantages and disadvantages. Methods: HYDROPS2-Mi2 EH images were acquired for 32 ears (16 patients): 16 ipsilateral ears of MD patients (MD-ears) and 16 contralateral ears. Three-T MR unit with a 32-channel phased-array coil/the contrast agent to fill the perilymphatic space and the HYDROPS2-Mi2 sequence. We calculated the EH% [(endolymph)/(endolymph+perilymph)] ratio and analyzed the entire inner ear in terms of the volumetric EH% value, but only single cochlear and vestibular slices were subjected to planimetric EH% evaluation. The EH% values were compared between MD ears and non-MD ears, to evaluate the diagnostic accuracy of the two methods. Results: The volumetric EH% was significantly higher for MD vestibules (50.76 ± 13.78%) than non-MD vestibules (39.50 ± 8.99%). The planimetric EH% was also significantly higher for MD vestibules (61.98 ± 20.65%) than non-MD vestibules (37.22 ± 12.95%). The vestibular and cochlear volumetric EH% values correlated significantly with the planimetric EH% values of the MD ear. Conclusion: Volumetric and planimetric EH measurements facilitate diagnosis of MD ears compared to non-MD ears. Both methods seem to be reliable and consistent; the measurements were significantly correlated in this study. However, the planimetric EH% overestimates the extent of vestibular hydrops by 26.26%. Also, planimetric data may not correlate with volumetric data for non-MD cochleae with normal EH% values.

Non-uniform gastric wall kinematics revealed by 4D Cine magnetic resonance imaging in humans

BACKGROUND

Assessment of gastric function in humans has relied on modalities with varying degrees of invasiveness, which are usually limited to the evaluation of single aspects of gastric function, thus requiring patients to undergo a number of often invasive tests for a full clinical understanding. Therefore, the development of a non-invasive tool able to concurrently assess multiple aspects of gastric function is highly desirable for both research and clinical assessments of gastrointestinal (GI) function. Recently, technological advances in magnetic resonance imaging (MRI) have provided new tools for dynamic (or "cine") body imaging. Such approaches can be extended to GI applications.

METHODS

In the present work, we propose a non-invasive assessment of gastric function using a four-dimensional (4D, volumetric cine imaging), free-breathing MRI sequence with gadolinium-free contrast enhancement achieved through a food-based meal. In healthy subjects, we successfully estimated multiple parameters describing gastric emptying, motility, and peristalsis propagation patterns.

KEY RESULTS

Our data demonstrated non-uniform kinematics of the gastric wall during peristaltic contraction, highlighting the importance of using volumetric data to derive motility measures.

CONCLUSIONS & INFERENCES

MRI has the potential of becoming an important clinical and gastric physiology research tool, providing objective parameters for the evaluation of impaired gastric function.

Prognostic Value of Combing Primary Tumor and Nodal Glycolytic-Volumetric Parameters of 18F-FDG PET in Patients with Non-Small Cell Lung Cancer and Regional Lymph Node Metastasis

We investigated whether the combination of primary tumor and nodal ¹⁸F-FDG PET parameters predict survival outcomes in patients with nodal metastatic non-small cell lung cancer (NSCLC) without distant metastasis. We retrospectively extracted pre-treatment ¹⁸F-FDG PET parameters from 89 nodal-positive NSCLC patients (stage IIB–IIIC). The Cox proportional hazard model was used to identify independent prognosticators of overall survival (OS) and progression-free survival (PFS). We devised survival stratification models based on the independent prognosticators and compared the model to the American Joint Committee on Cancer (AJCC) staging system using Harrell’s concordance index (c-index). Our results demonstrated that total TLG (the combination of primary tumor and nodal total lesion glycolysis) and age were independent risk factors for unfavorable OS (p < 0.001 and p = 0.001) and PFS (both p < 0.001), while the Eastern Cooperative Oncology Group scale independently predicted poor OS (p = 0.022). Our models based on the independent prognosticators outperformed the AJCC staging system (c-index = 0.732 versus 0.544 for OS and c-index = 0.672 versus 0.521 for PFS, both p < 0.001). Our results indicate that incorporating total TLG with clinical factors may refine risk stratification in nodal metastatic NSCLC patients and may facilitate tailored therapeutic strategies in this patient group.

Magnetic resonance imaging of the normal canine eye using a T1-weighted volumetric acquisition

PURPOSE

MRI is becoming increasingly available within the veterinary profession, and eyes are frequently included as part of a cranial study. The advantages of volumetric imaging are numerous, when compared to traditional two-dimensional imaging, and could be utilised within the veterinary setting. This report describing the normal MRI appearance of the canine eye, aimed to establish a standard reference range on a T1w volumetric acquisition.

METHOD

This study retrospectively assessed 62 eyes from 31 dogs that had undergone MRI at the Small Animal Hospital, Langford Vets, University of Bristol between 2016 and 2018 using a standardised MRI protocol. Dogs were excluded if they had presented with any reported ocular or orbital abnormalities. Measurements were performed from the 3D T1w volumetric sequence by a single observer using a previously published technique.

RESULTS

Mean axial globe length was 2.13 cm and equatorial width 2.16 cm. Mean anteroposterior depth of the anterior chamber was 0.40 cm and 0.97 cm for the vitreous chamber. The mean anteroposterior and equatorial distance of the lens was 0.75 cm and 1.15 cm, respectively. Mean optic nerve width was 0.15 cm, and the mean width of the entire optic nerve sheath was 0.43 cm. Statistically significant relationships were noted between age and axial globe length and both lens dimensions. Highly significant relationships were noted between all variables, except lens dimensions and body weight CONCLUSION: This study provides reference values to assist in the interpretation of ocular structures during MRI on a T1w volumetric acquisition.

Deformational changes after convection-enhanced delivery in the pediatric brainstem

OBJECTIVE

In the brainstem, there are concerns regarding volumetric alterations following convection-enhanced delivery (CED). The relationship between distribution volume and infusion volume is predictably greater than one. Whether this translates into deformational changes and influences clinical management is unknown. As part of a trial using CED for diffuse intrinsic pontine glioma (DIPG), the authors measured treatment-related volumetric alterations in the brainstem and ventricles.

METHODS

Enrolled patients underwent a single infusion of radioimmunotherapy. Between 2012 and 2019, 23 patients with volumetric pre- and postoperative day 1 (POD1) and day 30 (POD30) MRI scans were analyzed using iPlan® Flow software for semiautomated volumetric measurements of the ventricles and pontine segment of the brainstem.

RESULTS

Children in the study had a mean age of 7.7 years (range 2-18 years). The mean infusion volume was 3.9 ± 1.7 ml (range 0.8-8.8 ml). Paired t-tests demonstrated a significant increase in pontine volume immediately following infusion (p < 0.0001), which trended back toward baseline by POD30 (p = 0.046; preoperative 27.6 ± 8.4 ml, POD1 30.2 ± 9.0 ml, POD30 29.5 ± 9.4 ml). Lateral ventricle volume increased (p = 0.02) and remained elevated on POD30 (p = 0.04; preoperative 23.5 ± 15.4 ml, POD1 26.3 ± 16.0, POD30 28.6 ± 21.2). Infusion volume had a weak, positive correlation with pontine and lateral ventricle volume change (r2 = 0.22 and 0.27, respectively). Four of the 23 patients had an increase in preoperative neurological deficits at POD30. No patients required shunt placement within 90 days.

CONCLUSIONS

CED infusion into the brainstem correlates with immediate but self-limited deformation changes in the pons. The persistence of increased ventricular volume and no need for CSF diversion post-CED are inconsistent with obstructive hydrocephalus. Defining the degree and time course of these deformational changes can assist in the interpretation of neuroimaging along the DIPG disease continuum when CED is incorporated into the treatment algorithm.

Mammographic breast density and breast cancer risk: Evaluation using volumetric breast density software

Purpose

The study aimed to assess breast density as a risk factor for breast malignancy using automated volumetric breast density software and to study the relationship of breast density with tumor histopathological characteristics.

Materials and Methods

One hundred and thirty-four women with unilateral core biopsy-proven breast cancer were taken in the "case group." Two hundred and one women with normal bilateral screening mammograms were enrolled in the "control group." The cases and controls were further divided into pre- and post-menopausal subgroups. The mammograms of the contralateral breast of the cases and bilateral breasts of the controls were evaluated by automated volumetric breast density software and classified into four density grades. The tumor histopathological characteristics in the various density grades were also evaluated.

Results

In premenopausal women, the odds of having breast cancer was significantly higher for Grade 3 breasts (odds ratio [OR] 3.03; 95% confidence interval [CI]: [1.19-7.71]) versus Grade 1 and 2 breasts. Grade 4 premenopausal breasts also had greater odds (OR 3.09; 95% CI [0.89-10.78]) of developing breast cancer. No such relationship was established for postmenopausal women. No significant difference was seen in the histopathology of breast cancer among various breast density groups.

Conclusion

Increased breast density can be considered as an inherent, independent risk factor for breast cancer in premenopausal women.

Quantitative brain histogram of canine epilepsy using magnetic resonance imaging

BACKGROUND

Quantitative magnetic resonance imaging (MRI) is used to study the anatomy of the brain in dogs with idiopathic epilepsy.

PURPOSE

To quantitate MRI images in terms of volumetric ratios and histogram analyses of the following regions of interest (ROI) in dogs with idiopathic epilepsy: frontal; parietal; temporal; piriform; thalamic; and hippocampal regions.

MATERIAL AND METHODS

Nine dogs with epilepsy and four healthy controls were evaluated. We examined the volumetric ratios and histogram analyses of six ROIs in all dogs.

RESULTS

MR images, in T1-weighted, T2-weighted, FLAIR, diffusion-weighted imaging, and apparent diffusion coefficient sequences detected changes in 4/9 (44%) epileptic dogs found in 5/6 regions: frontal; parietal; temporal; piriform; and hippocampal regions. However, no such changes were observed in the thalamic region. Interestingly, the frontal and piriform volumetric ratios of epileptic dogs were significantly lower than those of control dogs. The histogram analyses in 4/6 regions were significantly increased in epileptic dogs.

CONCLUSION

Our results demonstrated MRI finding abnormalities in several regions of the brain in several sequences including T1-weighted, T2-weighted, FLAIR, diffusion-weighted imaging, and apparent diffusion coefficient in epileptic dogs. In several regions of the brain, atrophy may exist, and hyperintensity may be present on MR images in epileptic dogs. These findings suggest that the diagnostic yield of MRI, which is an advanced neuroimaging technique, is high in epileptic dogs and has good reliability and sensitivity in detecting abnormal areas in patients.

Volumetric Modeling of Adrenal Gland Size in Primary Bilateral Macronodular Adrenocortical Hyperplasia

CONTEXT

Radiological characterization of adrenal size in primary bilateral macronodular adrenocortical hyperplasia (PBMAH) has not been previously investigated.

OBJECTIVE

We hypothesized that volumetric modeling of adrenal gland size may correlate with biochemical disease severity in patients with PBMAH. Secondary analysis of patients with concurrent primary aldosteronism (PA) was performed.

DESIGN

A retrospective cross-sectional analysis of 44 patients with PBMAH was conducted from 2000 to 2019.

SETTING

Tertiary care clinical research center.

PATIENTS

Patients were diagnosed with PBMAH based upon clinical, genetic, radiographic and biochemical characteristics.

INTERVENTION

Clinical, biochemical, and genetic data were obtained. Computed tomography scans were used to create volumetric models by manually contouring both adrenal glands in each slice using Vitrea Core Fx v6.3 software (Vital Images, Minnetonka, Minnesota).

MAIN OUTCOME AND MEASURES

17-hydroxycorticosteroids (17-OHS), ARMC5 genetics, and aldosterone-to-renin ratio (ARR) were retrospectively obtained. Pearson test was used for correlation analysis of biochemical data with adrenal volume.

RESULTS

A cohort of 44 patients with PBMAH was evaluated, with a mean age (±SD) of 53 ± 11.53. Eight patients met the diagnostic criteria for PA, of whom 6 (75%) were Black. In the Black cohort, total adrenal volumes positively correlated with midnight cortisol (R = 0.76, P = 0.028), urinary free cortisol (R = 0.70, P = 0.035), and 17-OHS (R = 0.87, P = 0.0045), with a more pronounced correlation with left adrenal volume alone. 17-OHS concentration positively correlated with total, left, and right adrenal volume in patients harboring pathogenic variants in ARMC5 (R = 0.72, P = 0.018; R = 0.65, P = 0.042; and R = 0.73, P = 0.016, respectively).

CONCLUSIONS

Volumetric modeling of adrenal gland size may associate with biochemical severity in patients with PBMAH, with particular utility in Black patients.

Volumetric assessment of unaffected parenchyma and Wilms' tumours: analysis of response to chemotherapy and surgery using a semi-automated segmentation algorithm in children with renal neoplasms

OBJECTIVE

To present our proof of concept with semi-automatic image recognition/segmentation technology for calculation of tumour/parenchyma volume.

METHODS

We reviewed Wilms' tumours (WTs) between 2000 and 2018, capturing computed tomography images at baseline, after neoadjuvant chemotherapy (NaC) and postoperatively. Images were uploaded into MATLAB-3-D volumetric image processing software. The program was trained by two clinicians who supervised the demarcation of tumour and parenchyma, followed by automatic recognition and delineation of tumour margins on serial imaging, and differentiation from uninvolved renal parenchyma. Volume was automatically calculated for both.

RESULTS

During the study period, 98 patients were identified. Of these, based on image quality and availability, 32 (38 affected moieties) were selected. Most patients (65%) were girls, diagnosed at age 50 ± 37 months of age. NaC was employed in 64% of patients. Surgical management included 27 radical and 11 partial nephrectomies. Automated volume assessment demonstrated objective response to NaC for unilateral and bilateral tumours (68 ± 20% and 53 ± 39%, respectively), as well as preservation on uninvolved parenchyma with partial nephrectomy (70 ± 46 cm³ at presentation to 57 ± 41 cm³ post-surgery).

CONCLUSION

Volumetric analysis is feasible and allows objective assessment of tumour and parenchyma volume in response to chemotherapy and surgery. Our data show changes after therapy that may be otherwise difficult to quantify. Use of such technology may improve surgical planning and quantification of response to treatment, as well as serving as a tool to predict renal reserve and long-term changes in renal function.

Exploratory Study of Apparent Diffusion Coefficient Histogram Metrics in Assessing Pancreatic Malignancy

PURPOSE

To evaluate whole-lesion 3D-histogram apparent diffusion coefficient (ADC) metrics for assessment of pancreatic malignancy.

METHODS

Forty-two pancreatic malignancies (36 pancreatic adenocarcinoma [PDAC], 6 pancreatic neuroendocrine [PanNET]) underwent abdominal magnetic resonance imaging (MRI) with diffusion-weighted imaging before endoscopic ultrasound biopsy or surgical resection. Two radiologists independently placed 3D volumes of interest to derive whole-lesion histogram ADC metrics. Mann-Whitney tests and receiver operating characteristic analyses were used to assess metrics' diagnostic performance for lesion histology, T-stage, N-stage, and grade.

RESULTS

Whole-lesion ADC histogram metrics lower in PDACs than PanNETs for both readers (P ≤ .026) were mean ADC (area under the curve [AUC] = 0.787-0.792), mean of the bottom 10th percentile (mean_0-10) (AUC = 0.787-0.880), mean of the 10th-25th percentile (mean_10-25) (AUC = 0.884-0.917) and mean of the 25th-50th percentile (mean_25-50) (AUC = 0.829-0.829). For mean_10-25 (metric with highest AUC for identifying PDAC), for reader 1 a threshold > 0.94 × 10^-3 mm²/s achieved sensitivity 94% and specificity 83%, and for reader 2 a threshold > 0.82 achieved sensitivity 97% and specificity 67%. Metrics lower in nodal status ≥ N₁ than N₀ for both readers (P ≤ .043) were mean_0-10 (AUC = 0.789-0.822) and mean_10-25 (AUC = 0.800-0.822). For mean_10-25 (metric with highest AUC for identifying N₀), for reader 1 a threshold <1.17 achieved sensitivity 87% and specificity 67%, and for reader 2 a threshold <1.04 achieved sensitivity 87% and specificity 83%. No metric was associated with T-stage (P > .195) or grade (P > .215).

CONCLUSION

Volumetric ADC histogram metrics may serve as non-invasive biomarkers of pancreatic malignancy. Mean_10-25 outperformed standard mean for lesion histology and nodal status, supporting the role of histogram analysis.

Comparison of Radiographic Approaches to Assess Treatment Response in Pituitary Adenomas: Is RECIST or RANO Good Enough?

Context

Pituitary adenomas (PA) are often irregularly shaped, particularly posttreatment. There are no standardized radiographic criteria for assessing treatment response, substantially complicating interpretation of prospective outcome data. Existing imaging frameworks for intracranial tumors assume perfectly spherical targets and may be suboptimal.

Objective

To compare a three-dimensional (3D) volumetric approach against accepted surrogate measurements to assess PA posttreatment response (PTR).

Design

Retrospective review of patients with available pre- and postradiotherapy (RT) imaging. A neuroradiologist determined tumor sizes in one dimensional (1D) per Response Evaluation in Solid Tumors (RECIST) criteria, two dimensional (2D) per Response Assessment in Neuro-Oncology (RANO) criteria, and 3D estimates assuming a perfect sphere or perfect ellipsoid. Each tumor was manually segmented for 3D volumetric measurements. The Hakon Wadell method was used to calculate sphericity.

Setting

Tertiary cancer center.

Patients or Other Participants

Patients (n = 34, median age = 50 years; 50% male) with PA and MRI scans before and after sellar RT.

Interventions

Patients received sellar RT for intact or surgically resected lesions.

Main Outcome Measures

Radiographic PTR, defined as percent tumor size change.

Results

Using 3D volumetrics, mean sphericity = 0.63 pre-RT and 0.60 post-RT. With all approaches, most patients had stable disease on post-RT scan. PTR for 1D, 2D, and 3D spherical measurements were moderately well correlated with 3D volumetrics (e.g., for 1D: 0.66, P < 0.0001) and were superior to 3D ellipsoid. Intraclass correlation coefficient demonstrated moderate to good reliability for 1D, 2D, and 3D sphere (P < 0.001); 3D ellipsoid was inferior (P = 0.009). 3D volumetrics identified more potential partially responding and progressive lesions.

Conclusions

Although PAs are irregularly shaped, 1D and 2D approaches are adequately correlated with volumetric assessment.

Longitudinal Radiographic Outcomes of Vestibular Schwannoma in Single and Fractionated Stereotactic Radiosurgery: A Retrospective Cohort Study

Management of vestibular schwannoma (VS) includes stereotactic radiosurgery (SRS) in single or fractionated treatments. There is a paucity of literature on the three-dimensional (3D) volumetric kinetics and radiological changes following SRS and no consensus on appropriate post-SRS surveillance imaging timeline. This is a retrospective cohort study with institutional review board approval. A total of 55 patients met study criteria. We collected volumetric kinetic data in VS treated with SRS over time using a target volume contouring software. We also tracked radiographic phenomena such as pseudoprogression and necrosis. A secondary objective was to describe our overall treatment success rate and any failures. For all treatments groups, pseudoprogression most typically occurred within 12 months post-SRS, after which tumor volumes on average normalized and then decreased from pretreatment size at the last follow-up. Only two patients required salvage therapy post-SRS and were considered SRS treatment failures. Both patients were in the five-fraction cohort but with a lower biologically equivalent dose. Our study is first to collect 3D volumetric kinetics of VS following single and fractionated SRS in contrast to extrapolations from single and two-dimensional measurements. Our longitudinal data also show initial increases in volume in the first 12 months post-SRS followed by later declines, setting up interesting questions regarding the utility of early posttreatment surveillance imaging in the asymptomatic patient. Finally, we show low rates of treatment failure (3.6%) and show in our cohort that SRS dose de-escalation posed a risk of treatment failure.

Three-dimensional T1-weighted gradient echo is a suitable alternative to two-dimensional T1-weighted spin echo for imaging the canine brain

Volumetric imaging (VOL), a three‐dimensional magnetic resonance imaging (MRI) technique, has been described in the literature for evaluation of the human brain. It offers several advantages over conventional two‐dimensional (2D) spin echo (SE), allowing rapid, whole‐brain, isotropic imaging with submillimeter voxels. This retrospective, observational study compares the use of 2D T1‐weighted SE (T1W SE), with T1W VOL, for the evaluation of dogs with clinical signs of intracranial disease. Brain MRI images from 160 dogs who had T1W SE and T1W VOL sequences acquired pre‐ and postcontrast, were reviewed for presence and characteristics of intracranial lesions. Twenty‐nine of 160 patients were found to have intracranial lesions, all visible on both sequences. Significantly better grey‐white matter (GWM) differentiation was identified with T1W VOL (P < .001), with fair agreement between the two sequences (weighted κ = 0.35). Excluding a mild reduction in lesion intensity in three dogs precontrast on the T1W VOL images compared to T1W SE, and meningeal enhancement noted on the T1W VOL images in one dog, not identified on T1W SE, there was otherwise complete agreement between the two sequences. The T1W VOL sequence provided equivalent lesion evaluation and significantly improved GWM differentiation. Images acquired were of comparable diagnostic quality to those produced using a conventional T1W SE technique, for assessment of lesion appearance, number, location, mass effect, and postcontrast enhancement. T1W VOL, therefore, provides a suitable alternative T1W sequence for canine brain evaluation and can facilitate a reduction in total image acquisition time.

Volumetric Ca2+ Imaging in the Mouse Brain Using Hybrid Multiplexed Sculpted Light Microscopy

Calcium imaging using two-photon scanning microscopy has become an essential tool in neuroscience. However, in its typical implementation, the tradeoffs between fields of view, acquisition speeds, and depth restrictions in scattering brain tissue pose severe limitations. Here, using an integrated systems-wide optimization approach combined with multiple technical innovations, we introduce a new design paradigm for optical microscopy based on maximizing biological information while maintaining the fidelity of obtained neuron signals. Our modular design utilizes hybrid multi-photon acquisition and allows volumetric recording of neuroactivity at single-cell resolution within up to 1 × 1 × 1.22 mm volumes at up to 17 Hz in awake behaving mice. We establish the capabilities and potential of the different configurations of our imaging system at depth and across brain regions by applying it to in vivo recording of up to 12,000 neurons in mouse auditory cortex, posterior parietal cortex, and hippocampus.

Study the Longitudinal in vivo and Cross-Sectional ex vivo Brain Volume Difference for Disease Progression and Treatment Effect on Mouse Model of Tauopathy Using Automated MRI Structural Parcellation

Brain volume measurements extracted from structural MRI data sets are a widely accepted neuroimaging biomarker to study mouse models of neurodegeneration. Whether to acquire and analyze data in vivo or ex vivo is a crucial decision during the phase of experimental designs, as well as data analysis. In this work, we extracted the brain structures for both longitudinal in vivo and single-time-point ex vivo MRI acquired from the same animals using accurate automatic multi-atlas structural parcellation, and compared the corresponding statistical and classification analysis. We found that most gray matter structures volumes decrease from in vivo to ex vivo, while most white matter structures volume increase. The level of structural volume change also varies between different genetic strains and treatment. In addition, we showed superior statistical and classification power of ex vivo data compared to the in vivo data, even after resampled to the same level of resolution. We further demonstrated that the classification power of the in vivo data can be improved by incorporating longitudinal information, which is not possible for ex vivo data. In conclusion, this paper demonstrates the tissue-specific changes, as well as the difference in statistical and classification power, between the volumetric analysis based on the in vivo and ex vivo structural MRI data. Our results emphasize the importance of longitudinal analysis for in vivo data analysis.

Normative human brain volume growth

OBJECTIVE While there is a long history of interest in measuring brain growth, as of yet there is no definitive model for normative human brain volume growth. The goal of this study was to analyze a variety of candidate models for such growth and select the model that provides the most statistically applicable fit. The authors sought to optimize clinically applicable growth charts that would facilitate improved treatment and predictive management for conditions such as hydrocephalus. METHODS The Weibull, two-term power law, West ontogenic, and Gompertz models were chosen as potential models. Normative brain volume data were compiled from the NIH MRI repository, and the data were fit using a nonlinear least squares regression algorithm. Appropriate statistical measures were analyzed for each model, and the best model was characterized with prediction bound curves to provide percentile estimates for clinical use. RESULTS Each model curve fit and the corresponding statistics were presented and analyzed. The Weibull fit had the best statistical results for both males and females, while the two-term power law generated the worst scores. The statistical measures and goodness of fit parameters for each model were provided to assure reproducibility. CONCLUSIONS The authors identified the Weibull model as the most effective growth curve fit for both males and females. Clinically usable growth charts were developed and provided to facilitate further clinical study of brain volume growth in conditions such as hydrocephalus. The authors note that the homogenous population from which the normative MRI data were compiled limits the study. Gaining a better understanding of the dynamics that underlie childhood brain growth would yield more predictive growth curves and improved neurosurgical management of hydrocephalus.

Volumetric FDG PET analysis of global lung inflammation: new tool for precision medicine in pulmonary sarcoidosis?

Currently FDG PET/CT is used as a tool for detection of active sites of sarcoidosis. Routine clinical practice relies on qualitative assessment with visual interpretation. When semi quantitatively expressed, e.g. for scientific purposes, this often leads to dichotomous "positive" or "negative" results. Metabolic activity in the lungs or mediastinum can also be expressed by SUVmax, but this measure is based only on the intensity of a single voxel. Likely for this reason these parameters show poor correlation with variables such as serum biomarkers and suboptimally predict clinical response to treatment. The current study focusses on new volumetric quantification methods for FDG PET/CT. Specifically the percentage of lung volume with increased metabolic activity, "%SUV-high", and the average metabolic activity in the lung "SUVmean", shows significantly better correlation with conventional biomarkers for disease activity than PET dichotomous and SUVmax. Our proposed quantification method needs subsequent and larger studies, however it may open new possibilities for future quantitative research in lung inflammation, and improve precision medicine in sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 44-54).

Trait anxiety mediates the link between inferior frontal cortex volume and negative affective bias in healthy adults

Anxious individuals tend to show a negative affective bias in attention that likely reflects reduced executive control, a cognitive function associated with the inferior frontal cortex (IFC), particularly its posterior segment, pars opercularis. Here, we investigated the relations among gray matter volume in the pars opercularis of IFC, trait anxiety, and negative biases in attention, in healthy participants. Sixty-two adults underwent structural magnetic resonance imaging scanning, completed a trait anxiety measure, and performed an Affective Go/No-Go (AGN) task. IFC volumes were extracted using Freesurfer, and negative bias scores were calculated from AGN performance. Trait anxiety correlated negatively with left IFC volume, and positively with the negative bias in reaction time. Furthermore, trait anxiety mediated the negative relation between the IFC volume and the negative bias measure. Overall, the present findings extend previous understanding of the IFC involvement in anxiety at the structural level, and may inform the development of intervention programs targeting anxiety.

Simultaneous two-photon imaging and two-photon optogenetics of cortical circuits in three dimensions

The simultaneous imaging and manipulating of neural activity could enable the functional dissection of neural circuits. Here we have combined two-photon optogenetics with simultaneous volumetric two-photon calcium imaging to measure and manipulate neural activity in mouse neocortex in vivo in three-dimensions (3D) with cellular resolution. Using a hybrid holographic approach, we simultaneously photostimulate more than 80 neurons over 150 μm in depth in layer 2/3 of the mouse visual cortex, while simultaneously imaging the activity of the surrounding neurons. We validate the usefulness of the method by photoactivating in 3D selected groups of interneurons, suppressing the response of nearby pyramidal neurons to visual stimuli in awake animals. Our all-optical approach could be used as a general platform to read and write neuronal activity.

Modern microscopy provides a window into the brain. The first light microscopes were able to magnify cells only in thin slices of tissue. By contrast, today’s light microscopes can image cells below the surface of the brain of a living animal. Even so, this remains challenging for several reasons. One is that the brain is three-dimensional. Another is that brain tissue scatters light. Trying to view neurons deep within the brain is a little like trying to view them through a glass of milk. Most of the light scatters on its way through the tissue with the result that little of the light reaches the target neurons.

Yang et al. have now tackled these challenges using a technique called holography. Holography produces 3D images of objects by splitting a beam of light and then recombining the beams in a specific way. Yang et al. applied this technique to an infrared laser beam, opting for infrared because it scatters much less in brain tissue than visible light. Directing each of the infrared beams to a different neuron can produce 3D images of multiple cells within the brain’s outer layer, the cortex, all at the same time.

The holographic infrared microscope can be used alongside two techniques called optogenetics and calcium imaging, in which light-sensitive proteins are inserted into neurons. Depending on the proteins introduced, shining light onto the neurons will either change their activity, or cause them to fluoresce whenever they are active. Just as a computer can both “read” and “write” data, the holographic microscope can thus read out existing neuronal activity or write new patterns of activity. By combining these techniques, Yang et al. were able to stimulate more than 80 neurons at the same time – and meanwhile visualize the activity of the surrounding neurons – at multiple depths within the mouse cortex.

This new microscopy technique, while a clear advance over existing methods, still cannot image and control neurons throughout the entire cortex. The next goal is to further extend this method across multiple brain areas and manipulate the activity of any subset of neurons at will. Neuroscientists will greatly benefit from the ability to image and alter the activity of living neural circuits in 3D. In the future, clinicians may be able to use this technique to treat brain disorders by adjusting the activity of abnormal neural circuits.

Comparing subjective and objective image quality at two different radiation exposure ranges of the paranasal sinus CT examinations using a volumetric 320-row detector CT system

OBJECTIVES

To evaluate image quality of protocol including 135 kVp, 5 mAs and 80 kVp, 5 mAs in the paranasal sinus CT examinations using single volumetric 320-row multidetector CT technique.

METHODS

From September to December 2016, both of our control group including 135 kVp and 5 mAs and our study group including 80 kVp and 5 mAs paranasal CT protocols were simultaneously performed on 40 patients using single volumetric 320-row multidetector CT device. Image quality for bony structures, air-filled structures and soft tissues were independently assessed for each group by three blinded observers using a 3-point grading scale (0 = not diagnostic, 1 = partially diagnostic, 2 = diagnostic). Objective image quality was also performed by region of interests were placed on axial soft tissue reconstructions in both eye bulbs, retrobulbar fat and maxillary sinuses to obtain different values for aqueous tissue, soft tissue and air, respectively. Effective dose was calculated from the dose-length product.

RESULTS

The effective radiation dose which calculated for the control group scans was 0.037 ± 0.003 mSv. But, it was 0.0099 ± 0.001 mSv for the study group scans. The effective radiation dose of study group was statistically significant lower than control group (p < 0.001). Despite significant lowering of the radiation doses, image qualities were sufficient for evaluating all the bony structures, air-filled structures and soft tissues except for eye muscle, retrobulbar fat and eye bulb.

CONCLUSIONS

Our results present that our protocols for study and control group provide significant dose reduction without the loss of diagnostic image quality for paranasal sinus CT. Paranasal sinus CT imaging can be performed at very low radiation exposure maintaining high image quality using a single volume 320-row detector CT device using 135 kVp and 5 mAs.

Evaluation of a proper cutoff value on quantitative dual-energy perfusion CT for the assessment of acute pulmonary thromboembolism

Background The cutoff value for assessing the severity of acute pulmonary thromboembolism (PTE) using relative volumetric evaluations of dual-energy perfusion computed tomography (DEpCT) is unclear. Purpose To determine the proper cutoff value for determining the severity of PTE using DEpCT volumetry. Material and Methods A total of 185 patients with venous thromboembolism were included in this study, of whom 61 were diagnosed with acute PTE. DEpCT images were three-dimensionally reconstructed at the following attenuation ranges: 1-2 HU (V2), 1-10 HU (V10), and 1-120 HU (V120). The ratios of low perfusion areas associated with each threshold range per V120 were also calculated, and the relative ratios were expressed as %V2 to %V10. These values were compared with factors indicating the severity of PTE, including the pulmonary arterial pressure, heart rate, CT angiographic obstruction index (CTOI), and right/left ventricular diameter ratio (RV/LV). Results The area under the curve (AUC) of %V2 was highest (0.783) among these values (95% confidence interval, 0.710-0.856) based on the presence of IPCs. The %V2 showed moderate correlations with CTOI (r = 0.36, P = 0.005) and RV/LV (r = 0.36, P = 0.004) in the patients with acute PTE. Conclusion Volumetric evaluations of DEpCT images using the lowest attenuation threshold range (1-2 HU) exhibit the best correlation with factors suggesting the severity of acute PTE.

An MRI study of the corpus callosum in monkeys: Developmental trajectories and effects of neonatal hippocampal and amygdala lesions

This study provides the first characterization of early developmental trajectories of corpus callosum (CC) segments in rhesus macaques using noninvasive MRI techniques and assesses long-term effects of neonatal amygdala or hippocampal lesions on CC morphometry. In Experiment 1, 10 monkeys (5 males) were scanned at 1 week-2 years of age; eight additional infants (4 males) were scanned once at 1-4 weeks of age. The first 8 months showed marked growth across all segments, with sustained, albeit slower, growth through 24 months. Males and females had comparable patterns of CC maturation overall, but exhibited slight differences in the anterior and posterior segments, with greater increases in the isthmus for males and greater increases in the rostrum for females. The developmental changes are likely a consequence of varying degrees of axonal myelination, redirection, and pruning. In Experiment 2, animals with neonatal lesions of the amygdala (n = 6; 3 males) or hippocampus (n = 6; 4 males) were scanned at 1.5 years post-surgery and compared to scans of six control animals from Experiment 1. Whereas amygdala damage yielded larger rostral and posterior body segments, hippocampal damage yielded larger rostrum and isthmus. These differences demonstrate that early perturbations to one medial temporal lobe structure may produce extensive and long-lasting repercussions in other brain areas. The current findings emphasize the complexity of neural circuitry putatively subserving neurodevelopmental disorders such as autism spectrum disorder and Williams syndrome, which are each characterized by malformations and dysfunction of complex neural networks that include regions of the medial temporal lobe.

Mapping and Analysis of the Connectome of Sympathetic Premotor Neurons in the Rostral Ventrolateral Medulla of the Rat Using a Volumetric Brain Atlas

Spinally projecting neurons in the rostral ventrolateral medulla (RVLM) play a critical role in the generation of vasomotor sympathetic tone and are thought to receive convergent input from neurons at every level of the neuraxis; the factors that determine their ongoing activity remain unresolved. In this study we use a genetically restricted viral tracing strategy to definitively map their spatially diffuse connectome. We infected bulbospinal RVLM neurons with a recombinant rabies variant that drives reporter expression in monosynaptically connected input neurons and mapped their distribution using an MRI-based volumetric atlas and a novel image alignment and visualization tool that efficiently translates the positions of neurons captured in conventional photomicrographs to Cartesian coordinates. We identified prominent inputs from well-established neurohumoral and viscero-sympathetic sensory actuators, medullary autonomic and respiratory subnuclei, and supramedullary autonomic nuclei. The majority of inputs lay within the brainstem (88–94%), and included putative respiratory neurons in the pre-Bötzinger Complex and post-inspiratory complex that are therefore likely to underlie respiratory-sympathetic coupling. We also discovered a substantial and previously unrecognized input from the region immediately ventral to nucleus prepositus hypoglossi. In contrast, RVLM sympathetic premotor neurons were only sparsely innervated by suprapontine structures including the paraventricular nucleus, lateral hypothalamus, periaqueductal gray, and superior colliculus, and we found almost no evidence of direct inputs from the cortex or amygdala. Our approach can be used to quantify, standardize and share complete neuroanatomical datasets, and therefore provides researchers with a platform for presentation, analysis and independent reanalysis of connectomic data.

Endoscopic endonasal versus transcranial approach to tuberculum sellae and planum sphenoidale meningiomas in a similar cohort of patients

OBJECTIVE Planum sphenoidale (PS) and tuberculum sellae (TS) meningiomas cause visual symptoms due to compression of the optic chiasm. The treatment of choice is surgical removal with the goal of improving vision and achieving complete tumor removal. Two options exist to remove these tumors: the transcranial approach (TCA) and the endonasal endoscopic approach (EEA). Significant controversy exists regarding which approach provides the best results and whether there is a subset of patients for whom an EEA may be more suitable. Comparisons using a similar cohort of patients, namely, those suitable for gross-total resection with EEA, are lacking from the literature. METHODS The authors reviewed all cases of PS and TS meningiomas that were surgically removed at Weill Cornell Medical College between 2000 and 2015 (TCA) and 2008 and 2015 (EEA). All cases were shown to a panel of 3 neurosurgeons to find only those tumors that could be removed equally well either through an EEA or TCA to standardize both groups. Volumetric measurements of preoperative and postoperative tumor size, FLAIR images, and apparent diffusion coefficient maps were assessed by 2 independent reviewers and compared to assess extent of resection and trauma to the surrounding brain. Visual outcome and complications were also compared. RESULTS Thirty-two patients were identified who underwent either EEA (n = 17) or TCA (n = 15). The preoperative tumor size was comparable (mean 5.58 ± 3.42 vs 5.04 ± 3.38 cm³ [± SD], p = 0.661). The average extent of resection achieved was not significantly different between the 2 groups (98.80% ± 3.32% vs 95.13% ± 11.69%, p = 0.206). Postoperatively, the TCA group demonstrated a significant increase in the FLAIR/edema signal compared with EEA patients (4.15 ± 7.10 vs -0.69 ± 2.73 cm³, p = 0.014). In addition, the postoperative diffusion-weighted imaging signal of cytotoxic ischemic damage was significantly higher in the TCA group than in the EEA group (1.88 ± 1.96 vs 0.40 ± 0.55 cm³, p =0.008). Overall, significantly more EEA patients experienced improved or stable visual outcomes compared with TCA patients (93% vs 56%, p = 0.049). Visual deterioration was greater after TCA than EEA (44% vs 0%, p = 0.012). While more patients experienced postoperative seizures after TCA than after EEA (27% vs 0%, p = 0.038), there was a trend toward more CSF leakage and anosmia after EEA than after TCA (11.8% vs 0%, p = 0.486 and 11.8% vs 0%, p = 0.118, respectively). CONCLUSIONS In this small single-institution study of similarly sized and located PS and TS meningiomas, EEA provided equivalent rates of resection with better visual results, less trauma to the brain, and fewer seizures. These preliminary results merit further investigation in a larger multiinstitutional study and may support EEA resection by experienced surgeons in a subset of carefully selected PS and TS meningiomas.

Brain Lesions among Orally Fed and Gastrostomy-Fed Dysphagic Preterm Infants: Can Routine Qualitative or Volumetric Quantitative Magnetic Resonance Imaging Predict Feeding Outcomes?

INTRODUCTION

The usefulness of qualitative or quantitative volumetric magnetic resonance imaging (MRI) in early detection of brain structural changes and prediction of adverse outcomes in neonatal illnesses warrants further investigation. Our aim was to correlate certain brain injuries and the brain volume of feeding-related cortical and subcortical regions with feeding method at discharge among preterm dysphagic infants.

MATERIALS AND METHODS

Using a retrospective observational study design, we examined MRI data among 43 (22 male; born at 31.5 ± 0.8 week gestation) infants who went home on oral feeding or gastrostomy feeding (G-tube). MRI scans were segmented, and volumes of brainstem, cerebellum, cerebrum, basal ganglia, thalamus, and vermis were quantified, and correlations were made with discharge feeding outcomes. Chi-squared tests were used to evaluate MRI findings vs. feeding outcomes. ANCOVA was performed on the regression model to measure the association of maturity and brain volume between groups.

RESULTS

Out of 43 infants, 44% were oral-fed and 56% were G-tube fed at hospital discharge (but not at time of the study). There was no relationship between qualitative brain lesions and feeding outcomes. Volumetric analysis revealed that cerebellum was greater (p < 0.05) in G-tube fed infants, whereas cerebrum volume was greater (p < 0.05) in oral-fed infants. Other brain regions did not show volumetric differences between groups.

CONCLUSION

This study concludes that neither qualitative nor quantitative volumetric MRI findings correlate with feeding outcomes. Understanding the complexity of swallowing and feeding difficulties in infants warrants a comprehensive and in-depth functional neurological assessment.

Structural imaging in premanifest and manifest Huntington disease

Huntington disease (HD) neuropathology has a devastating effect on brain structure and consequently brain function; neuroimaging provides a means to assess these effects in gene carriers. In this chapter we first outline the unique utility of structural imaging in understanding HD and discuss some of the acquisition and analysis techniques currently available. We review the existing literature to summarize what we know so far about structural brain changes across the spectrum of disease from premanifest through to manifest disease. We then consider how these neuroimaging findings relate to patient function and nonimaging biomarkers, and can be used to predict disease onset. Finally we review the utility of imaging measures for assessment of treatment efficacy in clinical trials.

Fast comprehensive single-sequence four-dimensional pediatric knee MRI with T2 shuffling

PURPOSE

To develop and clinically evaluate a pediatric knee magnetic resonance imaging (MRI) technique based on volumetric fast spin-echo (3DFSE) and compare its diagnostic performance, image quality, and imaging time to that of a conventional 2D protocol.

MATERIALS AND METHODS

A 3DFSE sequence was modified and combined with a compressed sensing-based reconstruction resolving multiple image contrasts, a technique termed T₂ Shuffling (T₂ Sh). With Institutional Review Board (IRB) approval, 28 consecutive children referred for 3T knee MRI prospectively underwent a standard clinical knee protocol followed by T₂ Sh. T₂ Sh performance was assessed by two readers blinded to diagnostic reports. Interpretive discrepancies were resolved by medical record chart review and consensus between the readers and an orthopedic surgeon. Image quality was evaluated by rating anatomic delineation, with 95% confidence interval. A Wilcoxon rank-sum test assessed the null hypothesis that T₂ Sh structure delineation compared to conventional 2D is unchanged. Intraclass correlation coefficients were calculated for interobserver agreement. Imaging time of the conventional protocol and T₂ Sh was compared.

RESULTS

There was 81% and 87% concordance between T₂ Sh reports and diagnostic reports, respectively, for each reader. Upon consensus review, T₂ Sh had 93% sensitivity and 100% specificity compared to clinical reports for detection of clinically relevant findings. The 95% confidence interval of diagnostic or better rating was 95-100%, with 34-80% interobserver agreement. There was no significant difference in structure delineation between T₂ Sh and 2D, except for the retinaculum (P < 0.05), where 2D was preferred. Typical imaging time for T₂ Sh and the conventional exam was 7 and 13 minutes, respectively.

CONCLUSION

A single-sequence pediatric knee exam is feasible with T₂ Sh, providing multiplanar, reformattable 4D images.

LEVEL OF EVIDENCE

2 J. MAGN. RESON. IMAGING 2017;45:1700-1711.

Conductometric and volumetric studies of atorvastatin in aqueous solution of arginine from 298.15 to 313.15 K

Categorized as a Biopharmaceutics Classification System Class II drugs, atorvastatin (ATV) exhibits low aqueous solubility and bioavailability thus presenting an obstacle and great challenge to formulation researchers. Numerous studies are available in regard to the solubility enhancement of ATV, but very few actually describe this phenomenon in terms of thermodynamics and the solute-solvent interaction. Arginine (ARG) is an amino acid that has been reported to enhance the solubility of the highly insoluble wheat protein gluten through hydrogen bonding and π electron-cation interaction. To our knowledge, ARG has never been investigated as a solubility enhancement agent of aqueous insoluble drugs. Thus, this study aimed to elucidate the solute-solvent and solute-cosolute interactions and derive thermodynamic parameters that bolstered the solubility of ATV in the presence of ARG. We examined the electrolytic conductance and densities of ATV-ARG binary system covering the temperature ranging from 298.15 K to 313.15 K. Conductometric and volumetric parameters such as limiting molar conductance, association constants, limiting partial molar volumes, and expansibility values were calculated. Additionally, thermodynamic parameters (ΔG⁰, ΔH⁰, ΔS⁰, and E_s) involved in the association process of the solute in the aqueous solution of ARG were also determined.

Confidence in Assessment of Lumbar Spondylolysis Using Three-Dimensional Volumetric T2-Weighted MRI Compared With Limited Field of View, Decreased-Dose CT

Background:

Limited z-axis–coverage computed tomography (CT) to evaluate for pediatric lumbar spondylolysis, altering the technique such that the dose to the patient is comparable or lower than radiographs, is currently used at our institution. The objective of the study was to determine whether volumetric 3-dimensional fast spin echo magnetic resonance imaging (3D MRI) can provide equal or greater diagnostic accuracy compared with limited CT in the diagnosis of pediatric lumbar spondylolysis without ionizing radiation.

Hypothesis:

Volumetric 3D MRI can provide equal or greater diagnostic accuracy compared with low-dose CT for pediatric lumbar spondylolysis without ionizing radiation.

Study Design:

Clinical review.

Level of Evidence:

Level 2.

Methods:

Three pediatric neuroradiologists evaluated 2-dimensional (2D) MRI, 2D + 3D MRI, and limited CT examinations in 42 pediatric patients who obtained imaging for low back pain and suspected spondylolysis. As there is no gold standard for the diagnosis of spondylolysis besides surgery, interobserver agreement and degree of confidence were compared to determine which modality is preferable.

Results:

Decreased-dose CT provided a greater level of agreement than 2D MRI and 2D + 3D MRI. The kappa for rater agreement with 2D MRI, 2D + 3D MRI, and CT was 0.19, 0.32, and 1.0, respectively. All raters agreed in 31%, 40%, and 100% of cases with 2D MRI, 2D + 3D MRI, and CT. Lack of confidence was significantly lower with CT (0%) than with 2D MRI (30%) and 2D + 3D MRI (25%).

Conclusion:

For diagnosing spondylolysis, radiologist agreement and confidence trended toward improvement with the addition of a volumetric 3D MRI sequence to standard 2D MRI sequences compared with 2D MRI alone; however, agreement and confidence remain significantly greater using decreased-dose CT when compared with either MRI acquisition.

Clinical Relevance:

Decreased-dose CT of the lumbar spine remains the optimal examination to confirm a high suspicion of spondylolysis, with dose essentially equivalent to radiographs. If clinical symptoms are not classic for spondylolysis, 2D MRI is still very good at detecting spondylolysis while remaining sensitive for detection of alternative diagnoses such as disc abnormalities and pars stress reaction. The data suggest that standard 2D MRI sequences should not be entirely replaced by a volumetric T2-weighted 3D sequence (despite promising features of rapid acquisition time, increased spatial resolution, and reconstruction capability).

Long-term growth rate of vestibular schwannoma in neurofibromatosis 2: A volumetric consideration

OBJECTIVES/HYPOTHESIS

To determine the long-term growth rate of vestibular schwannoma (VS) in neurofibromatosis type 2 (NF2) patients based on volumetric measurements.

STUDY DESIGN

Retrospective review.

METHODS

We retrospectively reviewed magnetic resonance imaging (MRI) scans acquired from patients with NF2 from 1999 to 2013. Patients with an annual radiologic follow-up over at least 3 consecutive years were included. Volumetric VS growth was prospectively measured using a three-dimensional imaging workstation and through manual contouring of the lesion. Time to tumor progression was assessed according to the Response Evaluation in Neurofibromatosis and Schwannomatosis Tumor Measurement Group.

RESULTS

Eighteen patients presenting with a total of 26 VSs were included. The mean age at diagnosis was 26.1 years (range, 7 to 49 years). One hundred five MRI scans were analyzed during a median radiological follow-up of 5.6 years (range, 3 to 12 years). The annual volume and diameter growth rates were respectively 218.3 mm(3) /yr (range, -10 to 1,250 mm(3) /yr) and 0.9 mm/yr (range, -0.5 to 4.5 mm/yr). Time to tumor progression was 3 years (median survival). There was a weak correlation between volumetric and linear measurements (P < .0001, linear regression, n = 26, r(2) = 0.58). Among the 26 VSs, 76.9% (20/26) showed progression (VS growth more than 20%), 19.2% were stable, and 3.9% (1/26) exhibited shrinkage (spontaneous regression of more than 20% of the initial volume).

CONCLUSIONS

This study helps to assess the long-term growth profile of VS in a population of NF2 patients with untreated VS. These data could help to better acknowledge VS natural growth history.

LEVEL OF EVIDENCE

4 Laryngoscope, 126:2358-2362, 2016.

Solubility enhancement of simvastatin by arginine: thermodynamics, solute-solvent interactions, and spectral analysis

We examined the solubility of simvastatin in water in 0.01 mol·dm⁻³, 0.02 mol·dm⁻³, 0.04 mol·dm⁻³, 0.09 mol·dm⁻³, 0.18 mol·dm⁻³, 0.36 mol·dm⁻³, and 0.73 mol·dm⁻³ arginine (ARG) solutions. The investigated drug is termed the solute, whereas ARG the cosolute. Phase solubility studies illustrated a higher extent of solubility enhancement for simvastatin. The aforementioned system was subjected to conductometric and volumetric measurements at temperatures (T) of 298.15 K, 303.15 K, 308.15 K, and 313.15 K to illustrate the thermodynamics involved and related solute–solvent interactions. The conductance values were used to evaluate the limiting molar conductance and association constants. Thermodynamic parameters (ΔG⁰, ΔH⁰, ΔS⁰, and E_s) for the association process of the solute in the aqueous solutions of ARG were calculated. Limiting partial molar volumes and expansibilities were evaluated from the density values. These values are discussed in terms of the solute–solvent and solute–cosolute interactions. Further, these systems were analyzed using ultraviolet–visible analysis, Fourier-transform infrared spectroscopy, and ¹³C, ¹H, and two-dimensional nuclear overhauser effect spectroscopy nuclear magnetic resonance to complement thermophysical explanation.

An advanced shape-fitting algorithm applied to quadrupedal mammals: improving volumetric mass estimates

Body mass is a fundamental physical property of an individual and has enormous bearing upon ecology and physiology. Generating reliable estimates for body mass is therefore a necessary step in many palaeontological studies. Whilst early reconstructions of mass in extinct species relied upon isolated skeletal elements, volumetric techniques are increasingly applied to fossils when skeletal completeness allows. We apply a new 'alpha shapes' (α-shapes) algorithm to volumetric mass estimation in quadrupedal mammals. α-shapes are defined by: (i) the underlying skeletal structure to which they are fitted; and (ii) the value α, determining the refinement of fit. For a given skeleton, a range of α-shapes may be fitted around the individual, spanning from very coarse to very fine. We fit α-shapes to three-dimensional models of extant mammals and calculate volumes, which are regressed against mass to generate predictive equations. Our optimal model is characterized by a high correlation coefficient and mean square error (r (2)=0.975, m.s.e.=0.025). When applied to the woolly mammoth (Mammuthus primigenius) and giant ground sloth (Megatherium americanum), we reconstruct masses of 3635 and 3706 kg, respectively. We consider α-shapes an improvement upon previous techniques as resulting volumes are less sensitive to uncertainties in skeletal reconstructions, and do not require manual separation of body segments from skeletons.

What every ICU clinician needs to know about the cardiovascular effects caused by abdominal hypertension

The effects of increased intra-abdominal pressure (IAP) on cardiovascular function are well recognized and include a combined negative effect on preload, afterload and contractility. The aim of this review is to summarize the current knowledge on this topic. The presence of intra-abdominal hypertension (IAH) erroneously increases barometric filling pressures like central venous (CVP) and pulmonary artery occlusion pressure (PAOP) (since these are zeroed against atmospheric pressure). Transmural filling pressures (calculated by subtracting the pleural pressure from the end-expiratory CVP value) may better reflect the true preload status but are difficult to obtain at the bedside. Alternatively, since pleural pressures are seldom measured, transmural CVP can also be estimated by subtracting half of the IAP from the end-expiratory CVP value, since abdominothoracic transmission is on average 50%. Volumetric preload indicators, such as global and right ventricular end-diastolic volumes or the left ventricular end-diastolic area, also correlate better with true preload. When using functional hemodynamic monitoring parameters like stroke volume variation (SVV) or pulse pressure variation (PPV) one must bear in mind that increased IAP will increase these values (via a concomitant increase in intrathoracic pressure). The passive leg raising test may be a false negative in IAH. Calculation of the abdominal perfusion pressure (as mean arterial pressure minus IAP) has been shown to be a better resuscitation endpoint than IAP alone. Finally, it is re-assuring that transpulmonary thermodilution techniques have been validated in the setting of IAH and abdominal compartment syndrome. In conclusion, the clinician must be aware of the different effects of IAH on cardiovascular function in order to assess the volume status accurately and to optimize hemodynamic performance.