Dynamic Cervical Spinal Canal Stenosis: Identifying Imaging Risk Factors in Extended Positions

Study Design

A retrospective study at a single academic institution.

Purpose

This study aimed to identify imaging risk factors for stenosis in extended neck positions undetectable in preoperative neutral magnetic resonance imaging (MRI) and improving decompression strategies for cervical spine disorders.

Overview of Literature

Cervical disorders are influenced by various dynamic factors, with spinal stenosis appearing during neck extension. Despite the diagnostic value of dynamic cervical MRI, standard practice often uses neutral-position MRI, potentially influencing surgical outcomes.

Methods

This study analyzed 143 patients who underwent decompression surgery between 2012 and 2014, who had symptomatic cervical disorders and MRI evidence of spinal cord or nerve compression but had no history of cervical spine surgery. Patient demographics, disease type, Japanese Orthopedic Association score, and follow-up periods were recorded. Spinal surgeons conducted radiological evaluations to determine stenosis levels using computed tomography myelography or MRI in neutral and extended positions. Measurements such as dural tube and spinal cord diameters, cervical alignment, range of motion, and various angles and distances were also analyzed. The residual space available for the spinal cord (SAC) was also calculated.

Results

During extension, new stenosis frequently appeared caudal to the stenosis site in a neutral position, particularly at C5/C6 and C6/C7. A low SAC was identified as a significant risk factor for the development of new stenosis in both the upper and lower adjacent disc levels. Each 1-mm decrease in SAC resulted in an 8.9- and 2.7-fold increased risk of new stenosis development in the upper and lower adjacent disc levels, respectively. A practical SAC cutoff of 1.0 mm was established as the threshold for new stenosis development.

Conclusions

The study identified SAC narrowing as the primary risk factor for new stenosis, with a clinically relevant cutoff of 1 mm. This study highlights the importance of local factors in stenosis development, advocating for further research to improve outcomes in patient with cervical spine disorders.

Evaluation of pelvic structural abnormalities in primiparous women with stress urinary incontinence

INTRODUCTION AND HYPOTHESIS

The objective was to evaluate the morphological characteristics of pelvic floor structure specific to de novo stress urinary incontinence (SUI) in primiparous women using three-dimensional (3D) reconstruction fusion technology based on static MRI combined with dynamic MRI.

METHODS

Eighty-one primiparous women after the first vaginal delivery were studied, 40 with SUI and 41 without SUI. 3D reconstruction models based on static MRI were used to describe the anatomical abnormalities of pelvic floor tissues. Dynamic MRI was used to describe segmental activities of the urethra and vagina. The relationship between the morphometry and postpartum SUI was evaluated by logistic regression analysis and receiver operator characteristic curve.

RESULTS

The differences in the distance from the bladder neck to the pubic symphysis (BSD), the angle between the posterior wall of the urethra and the anterior wall of the vagina, the width of the distal region of the vagina, urethral length, urethral compression muscle volume (CUV), and pubovisceral muscle volume, puborectal muscle volume, were measured, and except for the extremity of the anterior urethral wall, the total displacements (TDs) of the other sites between the two groups were statistically significant (p < 0.05). Logistic regression analysis showed that the BSD decreased, the CUV decreased, the TDs of the first site and the eighth site increment correlated significantly with postpartum SUI occurrence (p < 0.05).

CONCLUSIONS

3D reconstruction fusion technology provides an important support for a precise assessment of the pelvic floor dysfunction. The BSD, CUV, and iliococcygeus muscle volume have certain values in predicting de novo SUI after first vaginal birth.

Predicting intraoperative hemorrhage during curettage treatment of cesarean scar pregnancy using free-breathing GRASP DCE-MRI

OBJECTIVE

To explore the feasibility of the golden-angle radial sparse parallel (GRASP) dynamic magnetic resonance imaging (MRI) technique in predicting the intraoperative bleeding risk of scar pregnancy.

METHODS

A total of 49 patients with cesarean scar pregnancy (CSP) who underwent curettage and GRASP-MRI imaging were retrospectively selected between January 2021 and July 2022. The pharmacokinetic parameters, including Wash-in, Wash-out, time to peck (TTP), initial area under the curve (iAUC), the transfer rate constant (Ktrans), constant flow rate (Kep), and volume of extracellular space (Ve), were calculated. The amount of intraoperative bleeding was recorded by a gynecologist who performed surgery, after which patients were divided into non-hemorrhage (blood loss ≤ 200 mL) and hemorrhage (blood loss > 200 mL) groups. The measured pharmacokinetic parameters were statistically compared using the t-test or Mann-Whitney U test with a significant level set to be p < 0.05. The receiver operating characteristic (ROC) curve was constructed, and the area under the curve (AUC) was calculated to evaluate each parameter's capability in intraoperative hemorrhage subgroup classification.

RESULTS

Twenty patients had intraoperative hemorrhage (blood loss > 200 mL) during curettage. The hemorrhage group had larger Wash-in, iAUC, Ktrans, Ve, and shorter TTP than the non-hemorrhage group (all P > 0.05). Wash-in had the highest AUC value (0.90), while Ktrans had the lowest value (0.67). Wash-out and Kep were not significantly different between the two groups.

CONCLUSION

GRASP DCE-MRI has the potential to forecast intraoperative hemorrhage during curettage treatment of CSP, with Wash-in exhibiting the highest predictive performance. This data holds promise for advancing personalized treatment. However, further study is required to compare its effectiveness with other risk factors identified through anatomical MRI and ultrasound.

Low-rank plus sparse joint smoothing model based on tensor singular value decomposition for dynamic MRI reconstruction

Dynamic magnetic resonance imaging (DMRI) is an important medical imaging modality, but the long imaging time limits its practical applications. This paper proposes a low-rank plus sparse joint smoothing model based on tensor singular value decomposition (T-SVD) to reconstruct DMR images from highly under-sampled k-t space data. The low-rank plus sparse tensor (ℒ+S) model decomposes the DMR data into a low-rank and sparse tensor, which naturally fits the dynamic MR images characteristics and exploits the spatiotemporal correlation of DMRI data to improve reconstruction effect. T-SVD is utilized in the ℒ+S model to maintain the intrinsic structure of the low-rank tensor and further enhance the low-rank property. In addition, considering the global multi-dimensional smoothness of the DMR images, the proposed method joint tensor total variation (TTV) constraints to utilize the smoothness of DMR images to obtain more reconstruction details while protecting the global structure. We conducted experiments on the dynamic cardiac datasets, and the experiment results show that the proposed method has superior performance to several state-of-the-art imaging methods.

Location and motion of vaginal pessaries in situ in women with successful and unsuccessful pessary treatment for pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to compare the location and motion of pessaries between women with pelvic organ prolapse (POP) with a successful (fitting) and unsuccessful (non-fitting) pessary treatment on dynamic magnetic resonance imaging (dMRI).

METHODS

A cross-sectional exploratory study of 15 women who underwent a mid-sagittal dMRI of the pelvic floor at rest, during contraction and during Valsalva with three different types of pessaries. The coordinates of the pessaries cross section, inferior pubic point (IPP) and sacrococcygeal junction (SCJ) were obtained and the location (position, orientation) and the motion (translation and rotation) were calculated. Differences between the groups and between the pessaries within the groups were compared.

RESULTS

Nine women with a fitting pessary and 6 women with a non-fitting pessary were selected. In the non-fitting group, the pessaries were positioned more caudally and rotated more in clockwise direction and descended more, but not significantly, during Valsalva compared with the fitting group. The Falk pessary was positioned more anteriorly in the fitting group and more cranially in the non-fitting group compared with the ring and ring with support pessary.

CONCLUSIONS

A non-fitting pessary was positioned more caudally at rest; on Valsalva, it rotated more clockwise and moved more caudally, suggesting that the dynamic characteristics of the pessary might play an important role in its effectiveness. Findings of this study serve as a basis for the development of new pessary designs.

Parallel non-Cartesian spatial-temporal dictionary learning neural networks (stDLNN) for accelerating 4D-MRI

Dynamic magnetic resonance imaging (MRI) acquisitions are relatively slow due to physical and physiological limitations. The spatial-temporal dictionary learning (DL) approach accelerates dynamic MRI by learning spatial-temporal correlations, but the regularization parameters need to be manually adjusted, the performance at high acceleration rate is limited, and the reconstruction can be time-consuming. Deep learning techniques have shown good performance in accelerating MRI due to the powerful representational capabilities of neural networks. In this work, we propose a parallel non-Cartesian spatial-temporal dictionary learning neural networks (stDLNN) framework that combines dictionary learning with deep learning algorithms and utilizes the spatial-temporal prior information of dynamic MRI data to achieve better reconstruction quality and efficiency. The coefficient estimation modules (CEM) are designed in the framework to adaptively adjust the regularization coefficients. Experimental results show that combining dictionary learning with deep neural networks and using spatial-temporal dictionaries can obviously improve the image quality and computational efficiency compared with the state-of-the-art non-Cartesian imaging methods for accelerating the 4D-MRI especially at high acceleration rate.

A segmentation-informed deep learning framework to register dynamic two-dimensional magnetic resonance images of the vocal tract during speech

Objective

Dynamic magnetic resonance (MR) imaging enables visualisation of articulators during speech. There is growing interest in quantifying articulator motion in two-dimensional MR images of the vocal tract, to better understand speech production and potentially inform patient management decisions. Image registration is an established way to achieve this quantification. Recently, segmentation-informed deformable registration frameworks have been developed and have achieved state-of-the-art accuracy. This work aims to adapt such a framework and optimise it for estimating displacement fields between dynamic two-dimensional MR images of the vocal tract during speech.

Methods

A deep-learning-based registration framework was developed and compared with current state-of-the-art registration methods and frameworks (two traditional methods and three deep-learning-based frameworks, two of which are segmentation informed). The accuracy of the methods and frameworks was evaluated using the Dice coefficient (DSC), average surface distance (ASD) and a metric based on velopharyngeal closure. The metric evaluated if the fields captured a clinically relevant and quantifiable aspect of articulator motion.

Results

The segmentation-informed frameworks achieved higher DSCs and lower ASDs and captured more velopharyngeal closures than the traditional methods and the framework that was not segmentation informed. All segmentation-informed frameworks achieved similar DSCs and ASDs. However, the proposed framework captured the most velopharyngeal closures.

Conclusions

A framework was successfully developed and found to more accurately estimate articulator motion than five current state-of-the-art methods and frameworks.

Significance

The first deep-learning-based framework specifically for registering dynamic two-dimensional MR images of the vocal tract during speech has been developed and evaluated.

Dynamic-MRI quantification of abdominal wall motion and deformation during breathing and muscular contraction

BACKGROUND AND OBJECTIVE

Biomechanical assessment of the abdominal wall represents a major prerequisite for a better understanding of physiological and pathological situations such as hernia, post-delivery recovery, muscle dystrophy or sarcopenia. Such an assessment is challenging and requires muscular deformations quantification which have been very scarcely reported in vivo. In the present study, we intended to characterize abdominal wall deformations in passive and active conditions using dynamic MRI combined to a semiautomatic segmentation procedure.

METHODS

Dynamic deformations resulting from three complementary exercises i.e. forced breathing, coughing and Valsalva maneuver were mapped in a transversal abdominal plane and so for twenty healthy volunteers. Real-time dynamic MRI series were acquired at a rate of 182 ms per image, then segmented semi-automatically to follow muscles deformation through each exercise. Circumferential and radial strains of each abdominal muscle were computed from the geometrical characteristics' quantification, namely the medial axis length and the thickness. Muscular radial displacement maps were computed using image registration.

RESULTS

Large variations in circumferential and radial strains were observed for the lateral muscles (LM) but remained low for the rectus abdominis muscles (RA). Contraction phases of each exercise led to LM muscle shortening down to -9.6 ± 5.9% during Valsalva maneuver with a 16.2 ± 9.6% thickness increase. Contraction also led to inward radial displacement of the LM up to 9.9 ± 4.1 mm during coughing. During maximal inhalation, a significant 10.0 ± 6.6% lengthening was quantified for LM while a significant thickness decrease was computed for the whole set of muscles (-14.7 ± 6.6% for LM and -7.3 ± 6.5% for RA). The largest displacement was observed for the medial part of RA (17.9 ± 8.0 mm) whereas the posterior part of LM underwent limited motion (2.8 ± 2.3 mm). Displacement rate and correlation between muscle thickness and medial axis length during each exercise provided insights regarding subject-specific muscle function.

CONCLUSIONS

Dynamic MRI is a promising tool for the assessment of the abdominal wall motion and deformations. The corresponding metrics which have been continuously recorded during the exercises provided global and regional quantitative information. These metrics offer perspectives for a genuine clinical evaluation tool dedicated to the assessment of abdominal muscles function in both healthy subjects and patients.

Clinicopathological predictors of postoperative upstaging to invasive ductal carcinoma (IDC) in patients preoperatively diagnosed with ductal carcinoma in situ (DCIS): a multi-institutional retrospective cohort study

Background

We conducted a prospective study with the intention to omit surgery for patients with ductal carcinoma in situ (DCIS) of the breast. We aimed to identify clinicopathological predictors of postoperative upstaging to invasive ductal carcinoma (IDC) in patients preoperatively diagnosed with DCIS.

Patients and methods

We retrospectively analyzed patients with DCIS diagnosed through biopsy between April 1, 2010 and December 31, 2014, from 16 institutions. Clinical, radiological, and histological variables were collected from medical records.

Results

We identified 2,293 patients diagnosed with DCIS through biopsy, including 1,663 DCIS (72.5%) cases and 630 IDC (27.5%) cases. In multivariate analysis, the presence of a palpable mass (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.2–2.6), mammography findings (≥ category 4; OR 1.8; 95% CI 1.2–2.6), mass formations on ultrasonography (OR 1.8; 95% CI 1.2–2.5), and tumor size on MRI (> 20 mm; OR 1.7; 95% CI 1.2–2.4) were independent predictors of IDC. Among patients with a tumor size on MRI of ≤ 20 mm, the possibility of postoperative upstaging to IDC was 22.1%. Among the 258 patients with non-palpable mass, nuclear grade 1/2, and positive for estrogen receptor, the possibility was 18.1%, even if the upper limit of the tumor size on MRI was raised to ≤ 40 mm.

Conclusion

We identified four independent predictive factors of upstaging to IDC after surgery among patients with DCIS diagnosed by biopsy. The combined use of various predictors of IDC reduces the possibility of postoperative upstaging to IDC, even if the tumor size on MRI is larger than 20 mm.

Deep-learning-based segmentation of the vocal tract and articulators in real-time magnetic resonance images of speech

BACKGROUND AND OBJECTIVE

Magnetic resonance (MR) imaging is increasingly used in studies of speech as it enables non-invasive visualisation of the vocal tract and articulators, thus providing information about their shape, size, motion and position. Extraction of this information for quantitative analysis is achieved using segmentation. Methods have been developed to segment the vocal tract, however, none of these also fully segment any articulators. The objective of this work was to develop a method to fully segment multiple groups of articulators as well as the vocal tract in two-dimensional MR images of speech, thus overcoming the limitations of existing methods.

METHODS

Five speech MR image sets (392 MR images in total), each of a different healthy adult volunteer, were used in this work. A fully convolutional network with an architecture similar to the original U-Net was developed to segment the following six regions in the image sets: the head, soft palate, jaw, tongue, vocal tract and tooth space. A five-fold cross-validation was performed to investigate the segmentation accuracy and generalisability of the network. The segmentation accuracy was assessed using standard overlap-based metrics (Dice coefficient and general Hausdorff distance) and a novel clinically relevant metric based on velopharyngeal closure.

RESULTS

The segmentations created by the method had a median Dice coefficient of 0.92 and a median general Hausdorff distance of 5mm. The method segmented the head most accurately (median Dice coefficient of 0.99), and the soft palate and tooth space least accurately (median Dice coefficients of 0.92 and 0.93 respectively). The segmentations created by the method correctly showed 90% (27 out of 30) of the velopharyngeal closures in the MR image sets.

CONCLUSIONS

An automatic method to fully segment multiple groups of articulators as well as the vocal tract in two-dimensional MR images of speech was successfully developed. The method is intended for use in clinical and non-clinical speech studies which involve quantitative analysis of the shape, size, motion and position of the vocal tract and articulators. In addition, a novel clinically relevant metric for assessing the accuracy of vocal tract and articulator segmentation methods was developed.

Real-time dynamic 3-T MRI assessment of spine kinematics: a feasibility study utilizing three different fast pulse sequences

BACKGROUND

Half-Fourier acquisition single-shot turbo spin-echo (HASTE), continuous radial gradient-echo (GRE), and True FISP allow real-time dynamic assessment of the spine.

PURPOSE

To evaluate the feasibility of adding dynamic sequences to routine spine magnetic resonance imaging (MRI) for assessment of spondylolisthesis.

MATERIAL AND METHODS

Retrospective review was performed of patients referred for dynamic MRI of the cervical or lumbar spine between January 2017 and 2018 who had flexion-extension radiographs within two months of MRI. Exclusion criteria were: incomplete imaging; spinal hardware; and inability to tolerate dynamic examination. Blinded, independent review by two board-certified musculoskeletal radiologists was performed to assess for spondylolisthesis (>3 mm translation); consensus review of dynamic radiographs served as the gold standard. Cervical spinal cord effacement was assessed. Inter-reader agreement and radiographic concordance was calculated for each sequence.

RESULTS

Twenty-one patients were included (8 men, 13 women; mean age 47.9 ± 16.5 years). Five had MRI of the cervical spine and 16 had MRI of the lumbar spine. Mean acquisition time was 18.4 ± 1.7 min with dynamic sequences in the range of 58-77 s. HASTE and True FISP had the highest inter-reader reproducibility (κ = 0.88). Reproducibility was better for the lumbar spine (κ = 0.94) than the cervical spine (κ = 0.28). Sensitivity of sequences for spondylolisthesis was in the range of 68.8%-78.6%. All three sequences had high accuracy levels: ≥90.5% averaged across the cervical and lumbar spine. Cervical cord effacement was observed during dynamic MRI in two cases (100% agreement).

CONCLUSION

Real-time dynamic MRI sequences added to spine MRI protocols provide reliable and accurate assessment of cervical and lumbar spine spondylolisthesis during flexion and extension.

Dynamic magnetic resonance imaging following native tissue vaginal reconstructive surgery; a prospective study

INTRODUCTION AND HYPOTHESIS

To describe the impact of native tissue vaginal reconstruction on pelvic anatomy using dynamic magnetic resonance imaging.

METHODS

This prospective single-cohort observational study involved women undergoing native tissue reconstruction with intraperitoneal vaginal vault suspension for pelvic organ prolapse. Concomitant procedures such as hysterectomy, midurethral sling, and anterior or posterior colporrhaphy were allowed. Enrolled participants underwent dynamic pelvic imaging pre- and postoperatively. Radiographic and anatomic measurements were compared. Secondary outcomes included validated patient questionnaires.

RESULTS

Fourteen participants were included in the analysis. The mean age was 62 years; all participants were Caucasian. Most participants had stage III pelvic organ prolapse. Significant improvements were noted in several radiographic measurements. The average H-line (representing levator hiatus width) with straining maneuvers improved following surgery (7.2 cm preoperatively vs. 6.6 cm postoperatively, p = 0.015). The average M-line (representing levator muscular descent) improved significantly with both straining (4.0 cm preoperatively vs. 3.0 cm postoperatively, p < 0.001) and defecatory maneuvers (6.2 cm preoperatively vs. 5.2 cm postoperatively, p = 0.001). The average size of cystocele improved from 5.6 cm (moderate) preoperatively to 0.7 cm (absent descent) postoperatively (p < 0.001). The average descent of the vaginal apex with defecation preoperatively was 3.0 cm (moderate) and 0 cm (absent descent) postoperatively (p = 0.003). Posterior compartment descent with defecation did not change following surgical intervention (5.8 cm preoperatively vs. 5.2 cm postoperatively, p = 0.056). Pelvic Organ Prolapse Quantification measurements improved in all compartments, and Pelvic Floor Distress Inventory-20 scores improved significantly following surgery (102 preoperatively vs. 30 postoperatively, p < 0.001).

CONCLUSIONS

Native tissue reconstruction with intraperitoneal vaginal vault suspension resulted in significant anatomic improvements, as defined by physical examination and dynamic magnetic resonance imaging.

Tumour heterogeneity revealed by unsupervised decomposition of dynamic contrast-enhanced magnetic resonance imaging is associated with underlying gene expression patterns and poor survival in breast cancer patients

BACKGROUND

Heterogeneity is a common finding within tumours. We evaluated the imaging features of tumours based on the decomposition of tumoural dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data to identify their prognostic value for breast cancer survival and to explore their biological importance.

METHODS

Imaging features (n = 14), such as texture, histogram distribution and morphological features, were extracted to determine their associations with recurrence-free survival (RFS) in patients in the training cohort (n = 61) from The Cancer Imaging Archive (TCIA). The prognostic value of the features was evaluated in an independent dataset of 173 patients (i.e. the reproducibility cohort) from the TCIA I-SPY 1 TRIAL dataset. Radiogenomic analysis was performed in an additional cohort, the radiogenomic cohort (n = 87), using DCE-MRI from TCGA-BRCA and corresponding gene expression data from The Cancer Genome Atlas (TCGA). The MRI tumour area was decomposed by convex analysis of mixtures (CAM), resulting in 3 components that represent plasma input, fast-flow kinetics and slow-flow kinetics. The prognostic MRI features were associated with the gene expression module in which the pathway was analysed. Furthermore, a multigene signature for each prognostic imaging feature was built, and the prognostic value for RFS and overall survival (OS) was confirmed in an additional cohort from TCGA.

RESULTS

Three image features (i.e. the maximum probability from the precontrast MR series, the median value from the second postcontrast series and the overall tumour volume) were independently correlated with RFS (p values of 0.0018, 0.0036 and 0.0032, respectively). The maximum probability feature from the fast-flow kinetics subregion was also significantly associated with RFS and OS in the reproducibility cohort. Additionally, this feature had a high correlation with the gene expression module (r = 0.59), and the pathway analysis showed that Ras signalling, a breast cancer-related pathway, was significantly enriched (corrected p value = 0.0044). Gene signatures (n = 43) associated with the maximum probability feature were assessed for associations with RFS (p = 0.035) and OS (p = 0.027) in an independent dataset containing 1010 gene expression samples. Among the 43 gene signatures, Ras signalling was also significantly enriched.

CONCLUSIONS

Dynamic pattern deconvolution revealed that tumour heterogeneity was associated with poor survival and cancer-related pathways in breast cancer.

[Pituitary gland tumors]

BACKGROUND

In this article, the most common pituitary gland tumors and the various differential diagnoses with focus on (neuro-)radiological diagnostic criteria are presented.

MATERIALS AND METHODS

An intensive, selective search of the literature in PubMed was carried out.

RESULTS

Pituitary adenomas account for approximately 10-15% of all intracranial brain tumors and are the most common tumors of the sellar region. Beyond a size of 10 mm they are called macroadenomas, under 10 mm microadenomas. They can be distinguished into hormone-active and non-active adenomas. Most of the hormone-active adenomas secrete prolactin (50%), more rarely somatotropin (10%) or corticotropin (5%). Tumors in the sellar region can arise from various tissues. Due to the anatomically complex location, local adjacent structures can be affected or compressed by the tumors. Particularly in case of suprasellar extension, visual impairment due to pressure on the optic chiasm is common. Important differential diagnoses for sellar tumors include craniopharyngiomas, meningiomas, metastases, aneurysms and Rathke cleft cysts. The task of image diagnostics is the early detection of the lesions as well as the proliferation pattern into perifocal structures. Gold standard is the thin-section, contrast-enhanced MRI examination. Dynamic contrast administration is crucial for the diagnosis of the microadenoma and the specific enhancement characteristic of some other tumors.

CONCLUSION

A highly focused imaging protocol is important for the diagnosis of sellar lesions such as pituitary tumors. The current favored modality is contrast-enhanced MRI, preferably with dynamic contrast-enhanced T1-weighted sequences. Early detection of the lesions and identification of the precise anatomical location are of great importance for diagnosis and therapy.

Application of dynamic magnetic resonance imaging information technology in adjuvant chemotherapy for breast cancer

In order to study the application of dynamic magnetic resonance imaging information technology in breast cancer adjuvant chemotherapy, female patients diagnosed with breast cancer in The People's Hospital of Shanxi Province are selected as research objects. Dynamic enhanced magnetic resonance imaging scans are performed to compare pathological changes by hematoxylin and eosin staining. The dynamic NMR morphological changes are used to evaluate the efficacy of neoadjuvant chemotherapy. Semi-quantitative analysis is used to compare the TIC types of lesions, and the changes in quantitative analysis parameters are used to evaluate the efficacy. The results show that in the dynamic magnetic resonance imaging technique, the effective group (RECIST standard is CR and PR) has statistically significant changes in the quantitative analysis parameters K^trans and K_ep before and after neoadjuvant chemotherapy. K^trans and K_ep are used in neoadjuvant chemotherapy for breast cancer. The assessment is consistent with the morphological RECIST criteria assessment and can be used for qualitative diagnosis of breast tumors.

Orthogonal tensor dictionary learning for accelerated dynamic MRI

A direct application of the compressed sensing (CS) theory to dynamic magnetic resonance imaging (MRI) reconstruction needs vectorization or matricization of the dynamic MRI data, which is composed of a stack of 2D images and can be naturally regarded as a tensor. This 1D/2D model may destroy the inherent spatial structure property of the data. An alternative way to exploit the multidimensional structure in dynamic MRI is to employ tensor decomposition for dictionary learning, that is, learning multiple dictionaries along each dimension (mode) and sparsely representing the multidimensional data with respect to the Kronecker product of these dictionaries. In this work, we introduce a novel tensor dictionary learning method under an orthonormal constraint on the elementary matrix of the tensor dictionary for dynamic MRI reconstruction. The proposed algorithm alternates sparse coding, tensor dictionary learning, and updating reconstruction, and each corresponding subproblem is efficiently solved by a closed-form solution. Numerical experiments on phantom and synthetic data show significant improvements in reconstruction accuracy and computational efficiency obtained by the proposed scheme over the existing method that uses the 1D/2D model with overcomplete dictionary learning. Graphical abstract Fig. 1 Comparison between (a) the traditional method and (b) the proposed method based on dictionary learning for dynamic MRI reconstruction.

Urethral length and bladder neck behavior: can dynamic magnetic resonance imaging give the same results as introital ultrasound?

PURPOSE

To compare dynamic magnetic resonance imaging (dMRI) and introital ultrasound results with regard to urethral length measurements and the evaluation of bladder neck changes.

METHODS

Retrospective analyses of urethral length measurements and detection of bladder neck changes (rotated/vertical bladder neck descent, urethral funneling) were conducted in women-scheduled for surgical treatment with alloplastic material-who had undergone introital ultrasound and dMRI presurgery and 3 months postsurgery. Measurement differences between both imaging modalities were evaluated by assessing the confidence interval for the difference in means between the datasets using bootstrap analysis.

RESULTS

Based on data from 40 patients (320 image series), the urethra could be clearly measured on every pre- and postsurgical dMRI dataset but not on preoperative ultrasound images in nine women during Valsalva maneuver due to a large cystocele. The estimation of the mean difference distribution based on 500,000 bootstrap resamples indicated that the urethral length was measured shorter by dMRI pre- and postsurgery at rest and postsurgery during Valsalva maneuver (median 1.6-3.1 mm) but longer by dMRI (median 0.2 mm) during Valsalva maneuver presurgery. Rotated/vertical bladder neck descent and urethral funneling diagnoses showed concordance of 67-74% in the direct comparison of patients; the estimation of the concordance indicated poorer outcomes with 50-72%.

CONCLUSIONS

Metric information on urethral length from dMRI is comparable to that from introital ultrasound. dMRI is more advantageous in cases with an extended organ prolapse. At present, dMRI does not give the same diagnosis on bladder neck changes as introital ultrasound does.

Five-year outcome after pelvic floor reconstructive surgery: evaluation using dynamic magnetic resonance imaging compared to clinical examination and quality-of-life questionnaire

Background Dynamic magnetic resonance imaging (dMRI) captures the entire pelvis during Valsalva maneuver and helps diagnosing pelvic floor changes after reconstructive surgery. Purpose To evaluate therapeutic outcome five years after reconstructive surgery using clinical examination, dMRI, and quality-of-life (QOL) questionnaire. Material and Methods Clinical examination, dMRI, and QOL questionnaire were conducted before surgery and in the follow-ups at 12 weeks, one year, and five years in women with pelvic organ prolapse (POP) stage ≥2. dMRI was performed at 1.5-T using a predefined protocol including sagittal T2-weighted (T2W) sequence at rest and sagittal T2W true-FISP sequence at maximum strain for metric POP measurements (reference points = bladder, cervix, pouch, rectum). Pelvic organ mobility (POM) was defined as the difference of the metric measurement at maximum strain and at rest. Results Twenty-six women with 104 MRI examinations were available for analysis. dMRI results mostly differ to clinical examination regarding the overall five-year outcome and the posterior compartment in particular. dMRI diagnosed substantially more patients with recurrent or de novo POP in the posterior compartment (n = 17) compared to clinical examination (n = 4). POM after five years aligns to preoperative status except for the bladder. POM reflects best the QOL results regarding defecation disorders. Conclusion A tendency for recurrent and de novo POP was seen in all diagnostic modalities applied. dMRI objectively visualizes the interaction of the pelvic organs and the pelvic floor after reconstructive surgery and POM correlated best with the women's personal impression on pelvic floor complaints.

Cervical Spine Prospective Feasibility Study : Dynamic Flexion-Extension Diffusion-Tensor Weighted Magnetic Resonance Imaging

PURPOSE

Diffusion tensor imaging (DTI) in flexion-extension may serve as a diagnostic tool to improve the sensitivity for detection of myelopathy. In this study, the feasibility and reproducibility of dynamic DTI in the cervical spinal cord was assessed in healthy volunteers and patients.

METHODS

All subjects were examined in maximum neck flexion-extension in a 3T magnetic resonance imaging (MRI) scanner. Range of motion, space available for the spinal cord, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured and compared between the neck positions.

RESULTS

Volunteers showed no variation in ADC and FA. In patients, extension produced higher ADC in the diseased than in the control segments (p = 0.0045). The ADC of the affected segments was higher in extension than in the neutral position (p = 0.0030) or in flexion (p = 0.0002). The FA was significantly lower in extension in patients at both the control level C2/3 (p = 0.0154) and the affected segment (p = 0.0187).

CONCLUSIONS

Dynamic DTI of the cervical spine is feasible and ADC increased in the patient group in extension. This finding may open a previously unexplored avenue to attempt an earlier identification of myelopathy.

Changes in the soleus H-reflex test and correlations between its results and dynamic magnetic resonance imaging abnormalities in patients with Hirayama disease

OBJECTIVE

To investigate changes in soleus H-reflex tests in patients with Hirayama disease (HD) and to analyse correlations between these changes and forward-shifting of the cervical cord during neck flexion.

METHODS

The amplitude of the soleus H-reflex with and without vibration on the Achilles tendon was recorded bilaterally in 81 HD patients and 34 controls to measure both the vibratory inhibition index (VII) and the H_max/M_max ratio. The maximum forward-shifting degree of cervical cord during neck flexion was measured using dynamic magnetic resonance imaging in all HD patients.

RESULTS

Significantly higher VII was recorded in 6/81 (7.4%) HD patients, along with abnormal H_max/M_max ratios in 5 of 6 cases. Compared to illness duration (r = 0.29-0.36, p < 0.05), the maximum forward-shifting degree of the cervical cord was more strongly correlated with both VII and the H_max/M_max ratio (r = 0.51-0.81, p < 0.05).

CONCLUSIONS

HD patients may develop cervical spinal cord injury with disease progression, and these lesions may be more likely to occur in cases with relatively severe cervical-flexion structural abnormalities even during early stages.

SIGNIFICANCE

More caution should be taken when managing HD patients with severe cervical-flexion abnormalities because of the possible early occurrence of upper motor neuron lesions.

Exploration for reliable radiographic assessment method for hinge-like hypermobility at atlanto-occipital joint

PURPOSE

Hinge-like hyper-mobility is occasionally observed at the atlanto-occipital (O-C1) joint. However, it has not been clear if this kind of hinge-like hyper-mobility at the O-C1 joint should be regarded as "pathologic", or referred to as "instability". To solve this issue, we aimed to establish a reliable radiographic assessment method for this specific type of O-C1 instability and figure out the "standard value" for the range of motion (ROM) of the O-C1 joint.

METHODS

To figure out the standard range of the O-C1 angle, we acquired magnetic resonance imaging (MRI) sagittal views of the cervical spine for 157 healthy volunteers [average: 37.4 year-old (yo)] without spine diseases, at neutral, maximum flexion and maximum extension positions.

RESULTS

The average value (AVE) for ROM of O-C1 angle was 9.91°. The standard value for ROM of O-C1 angle was calculated as 0°-21°. There was no statistically significant gender difference. We also found that the older population (≧ 40 yo) significantly had a larger ROM of O-C1 angle (AVE: 11.72°) compared to the younger population (< 40 yo) (AVE: 8.99°).

CONCLUSIONS

We consider that hinge-like instability at O-C1 joint, which cannot be assessed by measuring Powers ratio, can be assessed by measuring the range of O-C1 angles using dynamic-MRI. Evaluation of O-C1 instability is important especially when we perform surgical treatment for diseases with upper cervical instability (such as retro-odontoid pseudotumor). We consider that the current study provides important information in such a case.

Percent slope analysis of dynamic magnetic resonance imaging for assessment of chemotherapy response of osteosarcoma or Ewing sarcoma: systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review is to provide an up-to-date and unprecedented summary of percent slope analysis of dynamic magnetic resonance imaging (MRI) for the preoperative evaluation of the chemotherapy response of osteosarcoma or Ewing sarcoma.

MATERIALS AND METHOD

Studies evaluating dynamic MRI for the preoperative evaluation of the chemotherapy response of osteosarcoma or Ewing sarcoma were systematically searched for in MEDLINE, EMBASE, and Web of Science. More than 60 % reduction of the slope of the time intensity curve derived from dynamic MRI was defined as a positive response. Pooled sensitivity and specificity for each study were calculated into 2 × 2 contingency tables. The DerSimonian-Laird random-effects method was used for determining the pooled diagnostic odds ratio and the area under curve (AUC) of the summary receiver operating characteristic (SROC) curve.

RESULTS

A total of six studies with 66 patients who fulfilled all of the inclusion criteria were considered for the meta-analysis. The pooled sensitivity and specificity were 0.73 (95 % CI, 0.54-0.88) and 0.83 (95 % CI, 0.67-0.94), respectively. A significant difference was found between the good and poor responders in the diagnostic odds ratio. The SROC curve showed that the AUC was 0.839, indicating diagnostic accuracy in estimating good therapy response.

CONCLUSION

The slope of the time intensity curve derived from dynamic MRI was useful for evaluating the histological response of patients to neoadjuvant chemotherapy in osteosarcoma or Ewing sarcoma.

Dynamic diaphragmatic MRI during apnea struggle phase in breath-hold divers

The purpose of the study was to provide insight in diaphragmatic involuntary breathing movements (IBM) during struggle phase of apnea at total lung capacity (TLC) and functional residual capacity (FRC) using magnetic resonance imaging along with measurements of hemodynamics and arterial oxygenation. The study was performed in eight elite breath-hold divers. There was a similar increase in diaphragmatic cranio-caudal excursions towards the end of TLC and FRC apnea. The greatest diaphragmatic excursion in both apneas and during tidal breathing was in the middle and posterior part of the diaphragm. Diaphragm thickness in elite BHD was within the reference range of normal values suggesting no diaphragmatic hypertrophy in this population. We found that the range of diaphragmatic excursions increases toward the end of apneas. Additionally, our data suggest that the diaphragm participates in IBM occurrence and that various segments of the diaphragm behave nonhomogenously both in tidal breathing and IBMs.

Magnetic resonance imaging in assessment of stress urinary incontinence in women: Parameters differentiating urethral hypermobility and intrinsic sphincter deficiency

AIM: To define the magnetic resonance imaging (MRI) parameters differentiating urethral hypermobility (UH) and intrinsic sphincter deficiency (ISD) in women with stress urinary incontinence (SUI).

METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic (UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the high-resolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and the volunteer groups: (1) urethral angle; (2) bladder neck descent; (3) status of the periurethral ligaments, (4) vaginal shape; (5) urethral sphincter integrity, length and muscle thickness at mid urethra; (6) bladder neck funneling; (7) status of the puborectalis muscle; (8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows: (1) urethral mobility angle on Q-tip test; (2) Valsalva leak point pressure (VLPP) measured at 250 cc bladder volume; and (3) maximum urethral closure pressure (MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H₂O. The ISD incontinence was defined with MUCP pressure below 20 cm H₂O, and VLPP pressure less or equal to 60 cm H₂O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic (ROC) analysis. All statistical analyses were performed using STATA version 9.0 (StataCorp LP, College Station, TX).

RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group (P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis (area under the ROC = 0.944).

CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.

The responsiveness of novel, dynamic, contrast-enhanced magnetic resonance measures of total knee synovitis after intra-articular corticosteroid for painful osteoarthritis

OBJECTIVE

Sensitive biomarkers are needed to understand synovial response to therapy in osteoarthritis (OA). Dynamic, contrast-enhanced magnetic resonance imaging (DCE MRI) provides quantitative, novel measures of synovial inflammation. This exploratory study examined DCE-assessed synovial response to intra-articular corticosteroid (IACS).

METHODS

People with ACR clinical criteria OA knee underwent 3 T MRI pre- and 2 weeks post-IACS. Five MRI variables were assessed blindly: total synovial volume (semi-automated computer program), early enhancement rate (EER) and late enhancement ratio of the entire knee, synovial volume × late enhancement and a semi-quantitative (SQ) score (six sites scored 0-3). Clinical symptoms were assessed using pain visual analogue score (VAS) and WOMAC.

RESULTS

13 participants (5 male, mean age 63, mean pain VAS 66 mm mean body mass index (BMI) 31.3 kg/m(2)) were included. The majority of MRIs demonstrated no change in SQ score although the DCE variables changed to some extent in all. There was generally a reduction in synovial volume ((Wilcoxon test) median (interquartile range (IQR)) reduction 14 cm(3) (-1, 29)), EER (0.2% (-0.3, 0.6)) and late enhancement ratio (8% (-0.5, 41)). Synovial volume × late enhancement ratio demonstrated a substantive reduction (2250 (-930, 5630)) as well as the largest effect size, r = 0.45. There was a median 26% reduction in EER in participants with good symptomatic response to IACS, contrasting with a 23% increase in those who responded poorly.

CONCLUSIONS

DCE MRI may be more sensitive than a SQ score at detecting post-therapy synovial changes. The association between EER and symptomatic response to IACS may reflect a closer relation of this biomarker to synovial inflammation than with volumetric assessment.

Pancreatic carcinoma coexisting with chronic pancreatitis versus tumor-forming pancreatitis: Diagnostic utility of the time-signal intensity curve from dynamic contrast-enhanced MR imaging

AIM: To evaluate the ability of the time-signal intensity curve (TIC) of the pancreas obtained from dynamic contrast-enhanced magnetic resonance imaging (MRI) for differentiation of focal pancreatic masses, especially pancreatic carcinoma coexisting with chronic pancreatitis and tumor-forming pancreatitis.

METHODS: Forty-eight consecutive patients who underwent surgery for a focal pancreatic mass, including pancreatic ductal carcinoma (n = 33), tumor-forming pancreatitis (n = 8), and islet cell tumor (n = 7), were reviewed. Five pancreatic carcinomas coexisted with longstanding chronic pancreatitis. The pancreatic TICs were obtained from the pancreatic mass and the pancreatic parenchyma both proximal and distal to the mass lesion in each patient, prior to surgery, and were classified into 4 types according to the time to a peak: 25 s and 1, 2, and 3 min after the bolus injection of contrast material, namely, type-I, II, III, and IV, respectively, and were then compared to the corresponding histological pancreatic conditions.

RESULTS: Pancreatic carcinomas demonstrated type-III (n = 13) or IV (n = 20) TIC. Tumor-forming pancreatitis showed type-II (n = 5) or III (n = 3) TIC. All islet cell tumors revealed type-I. The type-IV TIC was only recognized in pancreatic carcinoma, and the TIC of carcinoma always depicted the slowest rise to a peak among the 3 pancreatic TICs measured in each patient, even in patients with chronic pancreatitis.

CONCLUSION: Pancreatic TIC from dynamic MRI provides reliable information for distinguishing pancreatic carcinoma from other pancreatic masses, and may enable us to avoid unnecessary pancreatic surgery and delays in making a correct diagnosis of pancreatic carcinoma, especially, in patients with longstanding chronic pancreatitis.