SPECT/CT imaging: clinical utility of an emerging technology

Update on Pediatric Nuclear Medicine in Acute Care

Various radiopharmaceuticals are available for imaging pediatric patients in the acute care setting. This article focuses on the common applications used on a pediatric patient in acute care. To confirm the clinical diagnosis of brain death, brain scintigraphy is considered accurate and has been favorably compared with other methods of detecting the presence or absence of cerebral blood flow. Ventilation-perfusion lung scans are easy and safe to perform with less radiation exposure than computed tomography pulmonary angiography and remain an appropriate procedure to perform on children with suspected pulmonary embolism as a first imaging test in a hemodynamically stable patient with no history of lung disease and normal chest radiograph. 99mTc-pertechnetate scintigraphy (Meckel's scan) is the best noninvasive procedure to establish the diagnosis of ectopic gastric mucosa in Meckel's diverticulum. 99mTcred blood cell scintigraphy generally is useful for assessing lower GI bleeding in patients from any cause. Hepatobiliary scintigraphy is the most accurate diagnostic imaging modality for acute cholecystitis. 99mTc-dimercaptosuccinic acid scintigraphy is the simplest, and the most reliable and sensitive method for the early diagnosis of focal or diffuse functional cortical damage. 99mTcmercaptoacetyltriglycine scintigraphy is used to evaluate for early and late complications of renal transplantation. Bone scintigraphy is a sensitive and noninvasive technique for diagnosis of bone disorders such as osteomyelitis and fracture. 18F-fluorodeoxyglucose-positron emission tomography could be valuable in the evaluation of fever of unknown origin in pediatric patients, with better sensitivity and significantly less radiation exposure than a gallium scan. Moving forward, further refinement of pediatric radiopharmaceutical administered activities, including dose reduction, greater radiopharmaceutical applications, and updated consensus guidelines is warranted, with the use of radionuclide imaging likely to increase.

Comparison of positional artifacts in myocardial perfusion imaging in supine and semi-reclining position using dedicated D-SPECT cardiac camera: validation using CT based attenuation correction

BACKGROUND

Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols.

METHODS

We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image.

RESULTS

In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments.

CONCLUSION

The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images.

The role of SPECT/CT in painful, noninfected knees after knee arthroplasty: a systematic review and meta-analysis-a diagnostic test accuracy review

PURPOSE

The aim of this systematic review was to present the current evidence on the clinical use of single-photon emission computed tomography/computed tomography (SPECT/CT) in the evaluation of noninfected painful knees after knee arthroplasty.

METHODS

Embase, PubMed, Google Scholar, Ovid, Scopus, Science Direct and the Cochrane Database of Systematic Reviews were searched from database inception to May 2022 following the PRISMA guidelines. As a primary outcome, we defined the role of SPECT/CT in the diagnostic approach to noninfected painful knee arthroplasty; as a secondary objective, we described the noninfection-related factors linked to painful knee arthroplasty. Pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio values and other indicators were calculated; receiver operating characteristic (ROC) curve analysis results and a summary of the areas under the curve (AUCs) from the included studies were reported. A Fagan plot, likelihood ratio plot and Deeks' funnel plot were generated and analysed. Methodological quality was assessed using the QUADAS-2 tool, and the certainty of evidence was assessed by the GRADE approach.

RESULTS

A total of 493 publications were identified, of which eight met the inclusion criteria, with a final pooled sample size of 308 patients. The pooled sensitivity and specificity of SPECT/CT in diagnosing the source of pain in painful knee prostheses were 0.86 (95% CI: 0.75-0.93) and 0.90 (95% CI: 0.79-0.96), respectively, with pooled +LR and -LR values of 8.9 (95% CI: 4.11-19.19) and 0.15 (95% CI: 0.09-0.28). The pooled diagnostic odds ratio was 57.35, and the area under the curve was 0.94. SPECT/CT highly accurately identified different sources of pain, such as loosening of the prosthetic components, patellofemoral overloading, instability, malalignment of the components and degeneration of the patellofemoral compartment. The confidence of the estimates was moderate according to the GRADE approach.

CONCLUSION

With demonstrated high sensitivity and specificity, as a diagnostic tool, SPECT/CT can identify the source of pain in painful knees after knee arthroplasty, particularly in cases of loosening, patellofemoral disorders and component malalignment (level of evidence III). These findings have significant clinical repercussions, such as in changing the initial diagnosis, identifying or excluding different causes of painful knee arthroplasties, guiding subsequent treatment and positively impacting the final clinical outcome. We moderately recommend the use of SPECT/CT for identifying the source of pain after knee arthroplasty according to the GRADE assessment. This review was preregistered in Prospero under code CRD42022320457.

Quantitative liver SPECT/CT is a novel tool to assess liver function, prognosis, and response to treatment in cirrhosis

Background

Functional liver reserve is an important determinant of survival in cirrhosis. The traditional indocyanine green test (ICG) is cumbersome. Hence, we developed and validated a novel liver imaging, a hybrid of SPECT and CT (Q-SPECT/CT), for evaluating disease severity, outcomes, and response to treatment in decompensated cirrhosis (DC).

Methods

We recruited a cohort of DC patients at a tertiary institute between 2016-2019. First, we standardized the Q-SPECT/CT across a predefined range of volumes through phantom experiments. Then we performed clinical and laboratory evaluations, ICG test (retention at 15 min), and Q-SPECT/CT at baseline and 12 months of granulocyte colony-stimulating factor (G-CSF) and standard medical treatment (SMT).

Results

In 109 DC patients, 87.1% males, aged 51 ± 10 years, MELD: 14 (7-21), the percent quantitative liver uptake (%QLU) on Q-SPECT/CT exhibited a strong correlation with CTP (r = -0.728, p < 0.001), MELD (r = -0.743; p < 0.001) and ICG-R-15 (r = -0.720, p < 0.001) at baseline. %QLU had the maximum discrimination (AUC: 0.890-0.920), sensitivity (88.9-90.3%), specificity (81.2-90.7%), and accuracy (85.8-89.4%) than liver volumes on Q-SPECT/CT or ICG test for classifying patients in CTP/MELD based prognostic categories. A significant increase in %QLU (26.09 ± 10.06 to 31.2 ± 12.19, p = 0.001) and improvement in CTP/MELD correlated with better survival of G-CSF treated DC patients (p < 0.05). SMT did not show any improvement in Q-SPECT/CT or clinical severity scores (p > 0.05). %QLU > 25 (adj.H.R.: 0.234, p = 0.003) and G-CSF treatment (adj.H.R.: 0.414, p = 0.009) were independent predictors of better 12-months survival in DC.

Conclusion

Q-SPECT/CT (%QLU) is a novel non-invasive, diagnostic, prognostic, and theragnostic marker of liver reserve and its functions in cirrhosis patients.

Clinical trial registration

Clinicaltrials.gov, NCT02451033 and NCT03415698.

[99Tc]Sestamibi bioaccumulation induces apoptosis in prostate cancer cells: an in vitro study

The main aim of this preliminary in vitro study was to evaluate both the uptake of [⁹⁹Tc]Sestamibi into prostate cancer cells and the relationship among [⁹⁹Tc]Sestamibi bioaccumulation, cancer cells proliferation and apoptosis. An in vitro study in which PC3 prostate cancer cell line was cultured with increasing doses of decayed sestamibi has been developed. Specifically, PC3 cells were incubated with three different concentrations of [⁹⁹Tc]Sestamibi: 10 µg/mL, 1 µg/mL, and 0.1 µg/mL Expression of apoptotic caspase-3 and AIF, as well as the ultrastructure of PC3 cells, were evaluated at T0 and after 24, 48, 72, and 120 h following [⁹⁹Tc]Sestamibi incubation. Data here reported showed the bioaccumulation of sestamibi in prostate cancer cells. As concern the cancer cell homeostasis, the treatment of PC3 cells with [⁹⁹Tc]Sestamibi strongly influenced the cells proliferation. Indeed, a significant reduction in the number of mitosis was observed. Noteworthy, the accumulation of sestamibi in prostate cancer cells was associated with the appearance of morphological signs of apoptosis. The increase in AIF and caspase 3 expression in prostate cancer cells treated with 10 µg/mL of [⁹⁹Tc]Sestamibi confirmed that this radiopharmaceutical can trigger the apoptosis. To the best of our knowledge, this preliminary study reported for the first time in vitro data about the uptake of sestamibi in prostate cancer cells. The evidence about the accumulation of sestamibi in prostate cancer cells and its role in the apoptosis process could open new clinical perspectives on the use of this radiopharmaceutical in both the diagnosis and treatment of prostate cancers.

Under-correction of preoperative varus alignment does not lead to a difference in in-vivo bone loading in 3D-SPECT/CT compared to neutral alignment

BACKGROUND

The aim was to investigate the correlation of bone tracer uptake (BTU) in SPECT/CT and changes in coronal knee alignment after total knee arthroplasty (TKA). We questioned if undercorrection of preoperative varus alignment leads to a difference in BTU compared to neutral alignment.

METHODS

Consecutive 66 patients who received SPECT/CT before and after TKA were retrospectively included. Adjusted mechanical alignment was the alignment target. The alignment of the knee was measured on 3D-CT by selecting standardized landmarks. Maximum (mean ± SD) and relative BTU (ratio to the reference) were recorded using a previously validated localization scheme (p < 0.05).

RESULTS

In the native group, 20 knees were aligned (30.3%) in valgus (HKA > 181.5°), 12 (18.2%) in neutral (178.5°-181.5°) and 34 (51.5%) in varus (HKA < 178°). Overall TKA changed the alignment towards neutral. 48.5% remained in the same groups, whereas 50% of native valgus and 33% of varus knees changed to neutral after TKA. In native varus alignment mean BTU was significantly higher in some medial tibial and femoral regions (fem1ia (p = 0.010), fem1ip (p = 0.002), tib1a.mid (p = 0.005), tib1a.tray (p = 0.000), tib1p.tray (p = 0.000)); in native valgus alignment mean BTU was higher in the corresponding lateral tibial and femoral regions (fem2ip (p = 0.001), tib2a.tray (p = 0.011), tib2p.tray (p = 0.002)). After TKA, a significant decrease in femoral and tibial BTU (femoral preoperative BTU 1.64 +/-0.69; femoral postoperative BTU 0.95 +/-0.42; p = 0.000// tibial preoperative BTU 1.65 +/- 0.93; tibial postoperative BTU 1.16 +/- 0.48; p = 0.000) and an increase in patellar BTU was observed (p = 0.025). Native varus alignment correlated with a higher medial BTU decrease medially. Undercorrection of preoperative varus alignment showed no higher BTU after TKA.

CONCLUSION

Preoperative varus alignment correlated with a higher decrease in BTU in specific femoral and tibial medial regions. Preoperative valgus alignment correlated with a higher decrease in the corresponding lateral regions. Undercorrection of preoperative varus alignment did not lead to higher bone loading reflected by BTU after TKA.

Detecting and Monitoring Hydrogels with Medical Imaging

Hydrogels, water-swollen polymer networks, are being applied to numerous biomedical applications, such as drug delivery and tissue engineering, due to their potential tunable rheologic properties, injectability into tissues, and encapsulation and release of therapeutics. Despite their promise, it is challenging to assess their properties in vivo and crucial information such as hydrogel retention at the site of administration and in situ degradation kinetics are often lacking. To address this, technologies to evaluate and track hydrogels in vivo with various imaging techniques have been developed in recent years, including hydrogels functionalized with contrast generating material that can be imaged with methods such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), optical imaging, and nuclear imaging systems. In this review, we will discuss emerging approaches to label hydrogels for imaging, review the advantages and limitations of these imaging techniques, and highlight examples where such techniques have been implemented in biomedical applications.

A brief review of reporter gene imaging in oncolytic virotherapy and gene therapy

Reporter gene imaging (RGI) can accelerate development timelines for gene and viral therapies by facilitating rapid and noninvasive in vivo studies to determine the biodistribution, magnitude, and durability of viral gene expression and/or virus infection. Functional molecular imaging systems used for this purpose can be divided broadly into deep-tissue and optical modalities. Deep-tissue modalities, which can be used in animals of any size as well as in human subjects, encompass single photon emission computed tomography (SPECT), positron emission tomography (PET), and functional/molecular magnetic resonance imaging (f/mMRI). Optical modalities encompass fluorescence, bioluminescence, Cerenkov luminescence, and photoacoustic imaging and are suitable only for small animal imaging. Here we discuss the mechanisms of action and relative merits of currently available reporter gene systems, highlighting the strengths and weaknesses of deep tissue versus optical imaging systems and the hardware/reagents that are used for data capture and processing. In light of recent technological advances, falling costs of imaging instruments, better availability of novel radioactive and optical tracers, and a growing realization that RGI can give invaluable insights across the entire in vivo translational spectrum, the approach is becoming increasingly essential to facilitate the competitive development of new virus- and gene-based drugs.

A clinical test examination procedure to identify knee compartment overloading: A reliability and validity study using SPECT-CT as reference

BACKGROUND

Mechanical forces and joint misalignment are considered risk factors for the development of knee osteoarthritis (KOA). Early detection of KOA and distinction between lateral and medial compartment overloading (CO), might be important to inform appropriate preventative interventions. This study evaluated reliability and validity of a test battery consisting of ten clinical tests to predict knee CO.

METHODS

Independent observers examined 30 participants with symptoms of KOA. Inter-rater reliability of the ten tests, as well as the anticipated CO based on the whole test battery, was determined. All participants received a SPECT-CT, which served as reference standard for CO. The agreement for CO between SPECT-CT and clinical examination was assessed to determine criterion validity.

RESULTS

The Kappa coefficients (k) for the ten individual clinical tests ranged from 0.19 to 0.80. The k for determining CO was 0.52 (95% CI = 0.28-0.76). The agreement for CO between SPECT-CT and clinical examination (i.e. criterion validity) yielded a k of 0.26 (95% CI = -0.06 - 0.58). Logistic regression indicated that valgus alignment was strongly related with lateral CO. No other relationships were found between individual tests and CO.

CONCLUSION

Accurate measurement of frontal plane knee angle is important to determine CO. This particular test yielded good reliability, but low validity. Reliability of the nine remaining clinical tests was fair to moderate. Criterion validity of the clinical examination to predict CO was low. Therefore, this test battery in its current form cannot be used in practice to determine CO.

Primary lung cancer with radioiodine avidity: A thyroid cancer cohort study

BACKGROUND

A proportion of lung cancers show sodium/iodide symporter (NIS) expression. Lung cancers with NIS expression may uptake radioiodine (RAI) and show RAI-avid lesions on RAI scan for differentiated thyroid cancer (DTC) surveillance.

AIM

To investigate the possibility of RAI uptake by lung cancer in a cohort with thyroid cancer.

METHODS

RAI-avid lung cancers were analyzed using a prospectively maintained database of patients with thyroid cancer who were registered at a medical center between December 1, 1976 and May 28, 2018. NIS expression in lung cancer was assessed using immunohistochemical staining.

RESULTS

Of the 5000 patients with thyroid cancer from the studied dataset, 4602 had DTC. During follow-up, 33 patients developed primary lung cancer. Of these patients, nine received an iodine-131 (¹³¹I) scan within 1 year before the diagnosis of lung cancer. One of these nine lung cancers was RAI-avid. NIS expression was evaluated, and three of the eight available lung cancers revealed NIS expression. The proportions of lung cancer cells with NIS expression were 60%, 15%, and 10%. The RAI-avid lung cancer had the highest level of expression (60%). The RAI-avid lung cancer had a spiculated border upon single-photon emission computed tomography/computed tomography, which led to an accurate diagnosis.

CONCLUSION

A proportion of lung cancer demonstrates NIS expression and is RAI-avid. Clinicians should be aware of this possibility in the interpretation of RAI scintigraphy.

Clinical usefulness of single photon emission tomography/computed tomography with stress analysis in early diagnoses of stem instability of noncemented hip arthroplasty

OBJECTIVE

Hip pain arising from implant instability is generally caused by repetitive stress injury, which subsequently leads to induction or exacerbation of abnormal metabolism of bone around the implant. single photon emission tomography/computed tomography (SPECT-CT) has advantages in localizing areas of increased tracer uptake that reflects such abnormal bone metabolism. Therefore, we investigated whether the application of SPECT/CT with stress analysis can be an effective practice in evaluating the instability of stem in noncemented hip arthroplasty or not.

METHOD

In total 16 patients were collected for unexplained painful hip arthroplasties. When physical examination and blood tests were unremarkable, radiographs were inconclusive and bone scan indicated increased scintigraphic uptake at the proximal part and at the tip of the stem; SPECT/CT was performed. Stem stability was assessed by measuring whether there was consistency between the increased scintigraphic uptake and the direction of the stress around the implant along with the location of the prosthesis.

RESULT

Among the 16 symptomatic hips, 9 hips showed the stability of the stem, 3 hips showed the stem instability and 4 hips showed the acetabular loosening with the stem stability. With the application of SPECT/CT with stress analysis, 15 out of 16 (93.7%) cases were found to have the change in the diagnoses, and managements were implemented in 11 out of 16 (68.7%) cases. When comparing before and after SPECT/CT, there was no significant association in clinical diagnosis and management (Pearson chi- square test = 4.61 and 1.33, P = 0.33 and 0.25).

CONCLUSION

SPECT/CT combined with stress analysis can be a useful tool in early diagnosis of stem instability and can assist surgeons in subsequent management and decision implementation when other radiographic imagings are inconclusive.

Physiologic colonic uptake of 18F-FDG on PET/CT is associated with clinical response and gut microbiome composition in patients with advanced non-small cell lung cancer treated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICI) represent the backbone treatment for advanced non-small cell lung cancer (NSCLC). Emerging data suggest that increased gut microbiome diversity is associated with favorable response to ICI and that antibiotic-induced dysbiosis is associated with deleterious outcomes. ¹⁸F-FDG physiologic colonic uptake on PET/CT increases following treatment with antibiotics (ATB) and could act as a surrogate marker for microbiome composition and predict prognosis. The aim of this study was to determine if ¹⁸F-FDG physiologic colonic uptake prior to ICI initiation correlates with gut microbiome profiling and clinical outcomes in patients with advanced NSCLC.

METHODS

Seventy-one patients with advanced NSCLC who underwent a PET/CT prior to ICI were identified. Blinded colonic contouring was performed for each colon segment and patients were stratified according to the median of the average colon SUV_max as well as for each segment in low vs. high SUV_max groups. Response rate, progression-free survival (PFS), and overall survival (OS) were compared in the low vs. high SUV_max groups. Gut microbiome composition was analyzed for 23 patients using metagenomics sequencing.

RESULTS

The high colon SUV_max group had a higher proportion of non-responders (p = 0.033) and significantly shorter PFS (4.1 vs. 11.3 months, HR 1.94, 95% CI 1.11-3.41, p = 0.005). High caecum SUV_max correlated with numerically shorter OS (10.8 vs. 27.6 months, HR 1.85, 95% CI 0.97-3.53, p = 0.058). Metagenomics sequencing revealed distinctive microbiome populations in each group. Patients with low caecum SUV_max had higher microbiome diversity (p = 0.046) and were enriched with Bifidobacteriaceae, Lachnospiraceae, and Bacteroidaceae.

CONCLUSIONS

Lower colon physiologic ¹⁸F-FDG uptake on PET/CT prior to ICI initiation was associated with better clinical outcomes and higher gut microbiome diversity in patients with advanced NSCLC. Here, we propose that ¹⁸F-FDG physiologic colonic uptake on PET/CT could serve as a potential novel marker of gut microbiome composition and may predict clinical outcomes in this population.

Mimics, pitfalls, and misdiagnoses of adrenal masses on CT and MRI

Due to the widespread use of imaging, incidental adrenal masses are commonly encountered. A number of pitfalls can result in misdiagnosis of these lesions, including inappropriate choice of imaging technique, presence of pseudolesions, and overlap of imaging features of different adrenal lesions. This article explores the potential pitfalls in imaging of the adrenal glands, on computed tomography and magnetic resonance imaging, that can lead to misinterpretation. Clues to correct diagnoses are provided to evade potential misinterpretation.

Smart diagnostic nano-agents for cerebral ischemia

A summary of the latest developments on imaging techniques and smart nano-diagnostics used for ischemic stroke.

Interstitial Lung Disease in Systemic Sclerosis: Focus on Early Detection and Intervention

Systemic sclerosis (SSc) is a progressive and often devastating disease characterized by autoimmune dysfunction, vasculopathy, and fibrosis. Interstitial lung disease (ILD) is identified in the majority of patients with SSc and is the leading cause of SSc-related mortality. Although clinical manifestations and ILD severity vary among patients, lung function typically declines to the greatest extent during the first 3-4 years after disease onset. We aim to provide an overview of SSc-associated ILD (SSc-ILD) with a focus on current and emerging tools for early diagnosis of ILD and current and novel treatments under investigation. Early detection of ILD provides the opportunity for early therapeutic intervention, which could improve patient outcomes. Thoracic high-resolution computed tomography is the most effective method of identifying ILD in patients with SSc; it enables detection of mild lung abnormalities and plays an important role in monitoring disease progression. Cyclophosphamide and mycophenolate mofetil are the most commonly prescribed treatments for SSc-ILD. Recently, nintedanib (an antifibrotic) was approved by the Food and Drug Administration for patients with SSc-ILD; it is indicated for slowing the rate of decline in pulmonary function. However, there is a need for additional effective and well-tolerated disease-modifying therapy. Ongoing studies are evaluating other antifibrotics and novel agents. We envision that early detection of lung involvement, combined with the emergence and integration of novel therapies, will lead to improved outcomes in patients with SSc-ILD.

Advanced modalities of molecular imaging in precision medicine for musculoskeletal malignancies

Musculoskeletal malignancies consist of a heterogenous group of mesenchymal tumors, often with high inter- and intratumoral heterogeneity. The early and accurate diagnosis of these malignancies can have a substantial impact on optimal treatment and quality of life for these patients. Several new applications and techniques have emerged in molecular imaging, including advances in multimodality imaging, the development of novel radiotracers, and advances in image analysis with radiomics and artificial intelligence. This review highlights the recent advances in molecular imaging modalities and the role of non-invasive imaging in evaluating tumor biology in the era of precision medicine.

Analysis of Mechanical Loading after Anatomic Anterior Cruciate Ligament Reconstruction Using Combined Single-Photon Emission Computerized Tomography and Conventional Computerized Tomography

Purpose

This study was to evaluate changes of the mechanical loading pattern after anatomic anterior cruciate ligament (ACL) reconstruction by analyzing uptake patterns using combined single-photon emission computerized tomography and conventional computerized tomography (SPECT/CT).

Materials and Methods

On SPECT/CT, high signal intensity of the articular surface which shows biological activity and mean increase of mechanical loading was compared with that of the tibiofemoral shaft as a comparative signal. The proportion of positive signals was evaluated in all compartments of the operated knee. Analysis was performed according to combined injury.

Results

A relatively high proportion of positive signals was detected in the posterior zone of the lateral tibial plateau (23.5%) and trochlear groove (23.5%) although increased signal intensity was detected in all compartments. There was no statistical difference depending on the presence of combined injury and between single-bundle and double-bundle ACL reconstruction.

Conclusions

Following anatomic ACL reconstruction, higher signal intensity was detected, particularly in the posterior part of the lateral tibial plateau and trochlear groove. Close observation for further signal changes or osteoarthritic changes would be required even if there was no combined injury and anatomic reconstruction was performed.

Incidental Detection of Bilateral Large Urinary Bladder Diverticulae on Tc99m Ethylene Dicysteine Renography with Single-photon Emission Computed Tomography-Computed Tomography

The complementary anatomical and functional information provided by hybrid imaging with single-photon emission computed tomography-CT (SPECT-CT) is a very useful imaging tool in selected cases where anatomical information is lacking as in the scenario of dynamic renal scintigraphy. The authors present a case of a 5-year-old male child with symptoms suggestive of cutis laxa with urinary tract infection. The child underwent dynamic renal scintigraphy with Tc99m ethylene dicysteine for cortical function and drainage assessment. Hybrid SPECT/CT proved valuable in the child in identification of the bilateral gross urinary bladder diverticulae.

Multifunctional PHPMA-Derived Polymer for Ratiometric pH Sensing, Fluorescence Imaging, and Magnetic Resonance Imaging

In this paper, we report synthesis and characterization of a novel multimodality (MRI/fluorescence) probe for pH sensing and imaging. A multifunctional polymer was derived from poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and integrated with a naphthalimide-based-ratiometric fluorescence probe and a gadolinium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex (Gd-DOTA complex). The polymer was characterized using UV-vis absorption spectrophotometry, fluorescence spectrofluorophotometry, magnetic resonance imaging (MRI), and confocal microscopy for optical and MRI-based pH sensing and cellular imaging. In vitro labeling of macrophage J774 and esophageal CP-A cell lines shows the polymer's ability to be internalized in the cells. The transverse relaxation time (T₂) of the polymer was observed to be pH-dependent, whereas the spin-lattice relaxation time (T₁) was not. The pH probe in the polymer shows a strong fluorescence-based ratiometric pH response with emission window changes, exhibiting blue emission under acidic conditions and green emission under basic conditions, respectively. This study provides new materials with multimodalities for pH sensing and imaging.

Production and separation of 43Sc for radiopharmaceutical purposes

Background

The favorable decay properties of ⁴³Sc and ⁴⁴Sc for PET make them promising candidates for future applications in nuclear medicine. An advantage ⁴³Sc (T_1/2 = 3.89 h, Eβ⁺_av = 476 keV [88%]) exhibits over ⁴⁴Sc, however, is the absence of co-emitted high energy γ-rays. While the production and application of ⁴⁴Sc has been comprehensively discussed, research concerning ⁴³Sc is still in its infancy. This study aimed at developing two different production routes for ⁴³Sc, based on proton irradiation of enriched ⁴⁶Ti and ⁴³Ca target material.

Results

⁴³Sc was produced via the ⁴⁶Ti(p,α)⁴³Sc and ⁴³Ca(p,n)⁴³Sc nuclear reactions, yielding activities of up to 225 MBq and 480 MBq, respectively. ⁴³Sc was chemically separated from enriched metallic ⁴⁶Ti (97.0%) and ⁴³CaCO₃ (57.9%) targets, using extraction chromatography. In both cases, ~90% of the final activity was eluted in a small volume of 700 μL, thereby, making it suitable for direct radiolabeling. The prepared products were of high radionuclidic purity, i.e. 98.2% ⁴³Sc were achieved from the irradiation of ⁴⁶Ti, whereas the product isolated from irradiated ⁴³Ca consisted of 66.2% ⁴³Sc and 33.3% ⁴⁴Sc. A PET phantom study performed with ⁴³Sc, via both nuclear reactions, revealed slightly improved resolution over ⁴⁴Sc. In order to assess the chemical purity of the separated ⁴³Sc, radiolabeling experiments were performed with DOTANOC, attaining specific activities of 5–8 MBq/nmol, respectively, with a radiochemical yield of >96%.

Conclusions

It was determined that higher ⁴³Sc activities were accessible via the ⁴³Ca production route, with a comparatively less complex target preparation and separation procedure. The product isolated from irradiated ⁴⁶Ti, however, revealed purer ⁴³Sc with minor radionuclidic impurities. Based on the results obtained herein, the ⁴³Ca route features some advantages (such as higher yields and direct usage of the purchased target material) over the ⁴⁶Ti path when aiming at ⁴³Sc production on a routine basis.

Electronic supplementary material

The online version of this article (10.1186/s41181-017-0033-9) contains supplementary material, which is available to authorized users.

SPECT/CT arthrography

Single photon emission CT (SPECT)/CT arthrography, the combination of CT arthrography and late phase bone SPECT/CT, has been developed in 2011 and so far used in knee, ankle and wrist joints. SPECT/CT offers functional information about increased bone turnover in combination with morphological details. Compared with SPECT/CT alone, additional intra-articular contrast enables the assessment of cartilage, menisci, ligaments and loose bodies. SPECT/CT arthrography is a promising alternative technique for the evaluation of internal derangement of joints in patients with MR contraindications and/or metallic implants. In this article, we review and report our 5-year experience with this technique illustrated with patient examples and give a perspective for future applications.

Incremental Value of Cocktail 18F-FDG and 18F-NaF PET/CT Over 18F-FDG PET/CT Alone for Characterization of Skeletal Metastases in Breast Cancer

PURPOSE

The aim of this study was to evaluate the incremental value of cocktail F-FDG/F-NaF PET/CT over F-FDG PET/CT alone for detection of skeletal metastases in breast cancer patients.

METHODS

Seventy patients with locally advanced/recurrent breast cancer were prospectively included. All patients underwent whole-body F-FDG PET/CT and cocktail F-FDG/F-NaF PET/CT within a span of 1 week. Both studies were evaluated to detect presence of skeletal/marrow metastases on PET/CT images by 2 nuclear medicine physicians. Clinical and radiological correlation/follow-up was used as criterion standard.

RESULTS

Of 70 patients, 50 (71.0%) had locally advanced breast cancer, and 20 had recurrent breast cancer. On patient-wise analysis, both cocktail PET/CT and F-FDG PET/CT identified skeletal/marrow lesions in 23 (32.8%) of 70 patients. In 8 patients (11.4%), only cocktail PET/CT identified skeletal/marrow lesions, whereas F-FDG PET/CT was negative. In the rest of the 39 patients (55.8%), no skeletal/marrow lesion was identified on both scans. Good correlation was noted between cocktail PET/CT and F-FDG PET/CT results (r = 0.785, P < 0.0001). Cocktail PET/CT detected lesions in significantly more number of patients than F-FDG PET/CT alone (P = 0.007). On lesion-wise analysis, cocktail PET/CT detected more number of lesions in 20 patients as compared with F-FDG-PET/CT alone. Both scans detected same number of lesions in the rest of 11 patients with positive findings. A total of 32 additional lesions were identified on cocktail PET/CT imaging as compared with F PET/CT alone (P < 0.0001).

CONCLUSIONS

Cocktail F-FDG and F-NaF PET/CT is superior to F-FDG PET/CT alone for the detection of skeletal/marrow metastases in breast cancer. It can be a better alternative to F-FDG PET/CT alone in facilities where both tracers are available.

The SPECT/CT Evaluation of Compartmental Changes after Open Wedge High Tibial Osteotomy

Purpose

The purpose of this study was to evaluate compartmental changes using combined single-photon emission computerized tomography and conventional computerized tomography (SPECT/CT) after open wedge high tibial osteotomy (OWHTO) for providing clinical guidance for proper correction.

Materials and Methods

Analysis was performed using SPECT/CT from around 1 year after surgery on 22 patients who underwent OWHTO. Postoperative mechanical axis was measured and classified into 3 groups: group I (varus), group II (0°–3° valgus), and group III (>3° valgus). Patella location was evaluated using Blackburne-Peel (BP) ratio. On SPECT/CT, the knee joint was divided into medial, lateral, and patellofemoral compartments and the brighter signal was marked as a positive signal.

Results

Increased signal activity in the medial compartment was observed in 12 cases. No correlation was observed between postoperative mechanical axis and medial signal increase. Lateral increased signal activity was observed in 3 cases, and as valgus degree increased, lateral compartment’s signal activity increased. Increased signal activity of the patellofemoral joint was observed in 7 cases, and significant correlation was observed between changes in BP ratio and increased signal activity.

Conclusions

For the treatment of medial osteoarthritis, OWHTO requires overcorrection that does not exceed 3 valgus. In addition, the possibility of a patellofemoral joint problem after OWHTO should be kept in mind.

MABS: targeted therapy tailored to the patient's need

Monoclonal antibodies (MABs) represent the window of opportunity in modern medicine. As immunology plays a vital role both in our survival and in disease development, MABs were found to be of great help in diagnosing, prognosticating and managing certain malignancies, inflammatory conditions, autoimmune as well as infectious diseases. Technological advances have enabled the production of MABs that target specific antigens linked with several disease processes. These drugs are now a component of therapy, not only for many common malignancies, including breast, colorectal, lung and pancreatic cancers, as well as lymphoma, leukaemia and multiple myeloma, but also for several inflammatory conditions such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis and inflammatory bowel disease. Targeted therapy has raised new questions about tailoring treatment, including cancer management, to the individual patient's needs. This would have a positive impact on the drug's effectiveness and toxicity as well as the economics of care. While targeted MABs are generally better tolerated than traditional chemotherapy, they are associated with several adverse effects, which vary from one patient to another.

Edge-oriented dual-dictionary guided enrichment (EDGE) for MRI-CT image reconstruction

In this paper, we formulate the joint/simultaneous X-ray CT and MRI image reconstruction. In particular, a novel algorithm is proposed for MRI image reconstruction from highly under-sampled MRI data and CT images. It consists of two steps. First, a training dataset is generated from a series of well-registered MRI and CT images on the same patients. Then, an initial MRI image of a patient can be reconstructed via edge-oriented dual-dictionary guided enrichment (EDGE) based on the training dataset and a CT image of the patient. Second, an MRI image is reconstructed using the dictionary learning (DL) algorithm from highly under-sampled k-space data and the initial MRI image. Our algorithm can establish a one-to-one correspondence between the two imaging modalities, and obtain a good initial MRI estimation. Both noise-free and noisy simulation studies were performed to evaluate and validate the proposed algorithm. The results with different under-sampling factors show that the proposed algorithm performed significantly better than those reconstructed using the DL algorithm from MRI data alone.

Role of SPECT-CT in breast cancer sentinel node biopsy when internal mammary chain drainage is observed

INTRODUCTION

SPECT-CT in the detection of the sentinel lymph node (SLN) of breast cancer offers known advantages over conventional planar lymphoscintigraphy. Sometimes, it shows atypical findings like mediastinal lymphatic drainage. We have evaluated these atypical findings showed by SPECT-CT performed in patients with migration to the internal mammary chain (IMC) and their roles in the management of the patients.

MATERIALS AND METHODS

We reviewed the 56 lymphoscintigraphies (planar and SPECT-CT) of 56 women (average age: 55 years) diagnosed with breast cancer with IMC migration observed in the planar images. We compared the two techniques, obtaining the number of depicted nodes, atypical locations, their exact anatomical location and their role in the management of the patient.

RESULTS

Planar images showed a total number of 81 IMC nodes. SPECT-CT showed 74 nodes in the IMC territory and 14 mediastinal lymphatic nodes in 6 patients. Out of the 81 IMC nodes reported by planar images, seven corresponded to mediastinal nodes. Planar and hybrid images showed 110 and 130 axillary nodes, respectively. SPECT-CT showed additional findings in five patients: three infraclavicular and two supraclavicular nodes that were exactly located. One intramammary node was discarded by the SPECT-CT as a focal skin contamination.

CONCLUSION

Mediastinal nodes are unexpected, but not uncommon findings that are important in the planning of SLN biopsy. SPECT-CT found more nodes than planar images, being able to separate mediastinal and IMC nodes, helping to exactly depict the SLN and its relations with anatomical structures.

Selective Spleen Scintigraphy in the Evaluation of Accessory Spleen/Splenosis in Splenectomized/Nonsplenectomized Patients and the Contribution of SPECT Imaging

OBJECTIVE

We aimed to evaluate the results of selective spleen scintigraphy (SSS) and contribution of SPECT imaging to planar imaging in splenectomized and nonsplenectomized patients.

METHODS

We retrospectively examined 112 SSSs of 96 patients. The patients were divided into two groups as splenectomized group (SP) and non-splenectomized group (NSP). The findings were evaluated by comparing the results of surgery,computerized tomography (CT), ultrasonography (USG) and magnetic resonance imaging (MRI). In addition, whether or not differences existed between the results of SPECT and planar imaging was determined.

RESULTS

Of 66 scintigraphies performed in the NSP group, 3 (5%) had positive, 3 (5%) had suspicious and 60 (90%) had negative results. In the NSP group, 28 patients underwent surgery and 12 accessory spleens were removed. Only 3 of these tissues were detected by scintigraphy. Of 46 patients in the SP group, 26 (57%) had positive findings whereas 20 (43%) had negative scintigraphies. Twelve accessory spleens/splenosis were removed surgically in 10 patients with a positive SSS in the SP group. There were no false positive results in both groups of patients who underwent surgery. There was no significant difference between the results of SSS, USG and CT. Of 39 patients to whom SPECT were performed, 10 had positive results both with planar and SPECT imaging. On the other hand, 26 patients, 3 of whom had suspected findings in SPECT images, demonstrated negative results when evaluated with both imaging methods. Remaining 3 were considered suspicious by only SPECT images for the hilar area.

CONCLUSION

SSS has high specificity in the detection of accessory spleens/splenosis. The sensitivity of SSS is low in the NSP group,but higher in the SP group. There is no contribution of SPECT imaging to planar imaging.

The usefulness of bone SPECT/CT imaging with volume of interest analysis in early axial spondyloarthritis

Background

The role of conventional bone scintigraphy in diagnosing early axial spondyloarthritis (SpA) is yet controversial. Single positron emission computed tomography (SPECT) plus CT is an imaging modality that adds better anatomical information to scintigraphy of the sacroiliac (SI) joint. Our aim was to investigate the usefulness of bone SPECT/CT with volume of interest (VOI) analysis in early axial SpA patients.

Methods

Twenty patients (male: female ratio = 12:8; age range = 17–65 years) presenting with inflammatory back pain meeting the Amor criteria of early axial SpA were recruited from a single center in South Korea. Bone scintigraphy was performed 180 min after intravenous injection of 1110 MBq of Tc-99 m-HDP, followed by bone SPECT/CT. The ratio between the entire SI joint and sacrum (SIS ratio) was measured by both bone SPECT/CT and bone scintigraphy. Data from 13 controls were also evaluated. Receiver operating characteristic (ROC) curve was plotted for further analysis, and the correlation between the SIS ratio and SI joint grade by plain radiography was assessed.

Results

The SIS ratio of early axial SpA patients vs. control subjects was significantly increased in bone SPECT/CT (p < 0.001). However, no significant difference was detected in bone scintigraphy. ROC curve analysis showed a significant difference in the area under curve (AUC) of bone SPECT/CT vs. bone scintigraphy (0.862 vs. 0.523, respectively; p < 0.001). With a cut-off SIS ratio of 1.50, ROC curve analysis showed a sensitivity of 80.0% and specificity of 84.6% in bone SPECT/CT. The SIS ratio measured in SPECT/CT, but not that measured in bone scintigraphy, was significantly increased with a higher grade of SI joint changes in plain radiography (p = 0.014).

Conclusion

Bone SPECT/CT is more useful than conventional bone scintigraphy in identifying sacroiliitis in early axial SpA patients, even with mild SI joint changes in plain radiography. By combining CT, we can accurately delineate the sacrum and SI joint uptake with our VOI method.

Role of SPECT/CT in sentinel lymph node detection in patients with breast cancer

AIM

The purpose of this study was to conduct a systematic review of the published literature to assess the role (indications, advantages, and limitations) of SPECT/CT for the detection of sentinel lymph node (SLN) in breast cancer.

METHODS

The authors searched PubMed for published literature in English addressing this topic.

RESULTS

Eleven studies, published since 2006, focused on the role and value of SPECT/CT for SLN detection (SLND). They showed that SPECT/CT improved sentinel node detection and anatomical localization. One study suggested that SPECT/CT may provide a more accurate staging. Limitations for SLND with SPECT/CT include extra time and inconvenience for the patient and additional radiation dose.

CONCLUSIONS

SPECT/CT is a valuable tool for SLND, especially in difficult cases, when planar lymphoscintigraphy shows no SLN or unexpected lymphatic drainage.

Usefulness of Additional SPECT/CT Identifying Lymphatico-renal Shunt in a Patient with Chyluria

Lymphoscintigraphy is known to be a useful and non-invasive modality for the evaluation of lymphatic abnormality. However, lymphoscintigraphy has limitations in evaluating chyluria because of its lack of anatomical information. Additional single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was considered to be potentially helpful in detecting the abnormal lymphatico-renal communication. A 20-year-old male patient was referred to our hospital for evaluation of recurrent chyluria. During the third recurrence of chyluria, additional SPECT/CT along with lymphoscintigraphy was performed for evaluation. From the combined SPECT/CT images, lymphatic drainage of radiotracers to the kidney was well visualized, helping diagnosis of a patient with chyluria.

[Nodes Dissections. What's up and what is at stake?]

Radical nodes dissection has a diagnostic value and can play a part in the treatment. Its interest could be questionable according to efficacy of the associated treatments either adjuvant or neo-adjuvant. Above all, sentinel node dissection allows to avoid a radical dissection with deleterious effects.

A free-response evaluation determining value in the computed tomography attenuation correction image for revealing pulmonary incidental findings: a phantom study

RATIONALE AND OBJECTIVES

The purpose of this study was to compare lesion-detection performance when interpreting computed tomography (CT) images that are acquired for attenuation correction when performing single photon emission computed tomography/computed tomography (SPECT/CT) myocardial perfusion studies. In the United Kingdom, there is a requirement that these images be interpreted; thus, it is necessary to understand observer performance on these images.

MATERIALS AND METHODS

An anthropomorphic chest phantom with inserted spherical lesions of different sizes and contrasts was scanned on five different SPECT/CT systems using site-specific CT protocols for SPECT/CT myocardial perfusion imaging. Twenty-one observers (0-4 years of CT experience) searched 26 image slices (17 abnormal, containing 1-3 lesions, and 9 normal, containing no lesions) for each CT acquisition. The observers marked and rated perceived lesions under the free-response paradigm. Four analyses were conducted using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis: (1) 20-pixel acceptance radius (AR) with all 21 readers, abbreviated to 20/ALL analysis, (2) 40-pixel AR with 21 readers (40/ALL), (3) 20-pixel AR with 14 readers experienced in CT (20/EXP), and (4) 20-pixel AR with 7 readers with no CT experience (20/NOT). The significance level of the test was set so as to conservatively control the overall probability of a type I error to <0.05.

RESULTS

The mean JAFROC figure of merit (FOM) for the five CT acquisitions for the 20/ALL study were 0.602, 0.639, 0.372, 0.475, and 0.719 with a significant difference in lesion-detection performance evident between all individual treatment pairs (P < .0001) with the exception of the 1-2 pairing, which was not significant (these differed only in milliamp seconds). System 5, which had the highest performance, had the smallest slice thickness and the largest matrix size. For the other analyses, the system orderings remained unchanged, and the significance of FOM difference findings remained identical to those for 20/ALL, with one exception: for 20/EXP analysis the 1-2 difference became significant with the higher milliamp seconds superior. Improved detection performance was associated with a smaller slice thickness, increased matrix size, and, to a lesser extent, increased tube charge.

CONCLUSIONS

Protocol variations for CT-based attenuation correction (AC) in SPECT/CT imaging have a measurable impact on lesion-detection performance. The results imply that z-axis resolution and matrix size had the greatest impact on lesion detection, with a weaker but detectable dependence on the product of milliamp and seconds.

Utility of SPECT/CT for periparotid sentinel lymph node mapping in the surgical management of head and neck melanoma

PURPOSE

Sentinel lymph node (SLN) biopsy is instrumental in staging and treatment of cutaneous melanoma. SPECT/CT, single-photon emission computed tomography (SPECT) integrated with computed tomography (CT), increases the accuracy of SLN mapping to improve surgical planning. SPECT/CT can correct for signal scatter to prevent masking, which is especially common in the head and neck. For periparotid lymph nodes SPECT/CT may improve localization of SLNs compared to lymphoscintigraphy.

MATERIALS/METHODS

Hospital charts were reviewed for 14 patients with melanoma and suspected lymphatic drainage to the parotid region who received lymphoscintigraphy followed by SPECT/CT prior to surgical excision and SLN.

RESULTS

Overall, SPECT/CT provided data, which changed management in 57% of patients.

CONCLUSIONS

Fifty-seven percent of our patients benefited from use of SPECT/CT. The distinction between level II and parotid sentinel lymph nodes was clearly identified through SPECT/CT images. We believe that patients with melanoma draining to the parotid region would benefit from SPECT/CT SLN mapping.

SPECT/CT workflow and imaging protocols

PURPOSE

Introducing a hybrid imaging method such as single photon emission computed tomography (SPECT)/CT greatly alters the routine in the nuclear medicine department. It requires designing new workflow processes and the revision of original scheduling process and imaging protocols. In addition, the imaging protocol should be adapted for each individual patient, so that performing CT is fully justified and the CT procedure is fully tailored to address the clinical issue. Such refinements often occur before the procedure is started but may be required at some intermediate stage of the procedure. Furthermore, SPECT/CT leads in many instances to a new partnership with the radiology department. This article presents practical advice and highlights the key clinical elements which need to be considered to help understand the workflow process of SPECT/CT and optimise imaging protocols.

METHODS

The workflow process using SPECT/CT is complex in particular because of its bimodal character, the large spectrum of stakeholders, the multiplicity of their activities at various time points and the need for real-time decision-making.

RESULTS

With help from analytical tools developed for quality assessment, the workflow process using SPECT/CT may be separated into related, but independent steps, each with its specific human and material resources to use as inputs or outputs. This helps identify factors that could contribute to failure in routine clinical practice. At each step of the process, practical aspects to optimise imaging procedure and protocols are developed. A decision-making algorithm for justifying each CT indication as well as the appropriateness of each CT protocol is the cornerstone of routine clinical practice using SPECT/CT.

CONCLUSION

In conclusion, implementing hybrid SPECT/CT imaging requires new ways of working. It is highly rewarding from a clinical perspective, but it also proves to be a daily challenge in terms of management.

SPECT-CT: applications in musculoskeletal radiology

This article reviews the technique, basic science principles and applications of integrated single photon emission CT (SPECT)-CT in musculoskeletal radiology. A review of the current evidence on the topic was undertaken, and selected clinical cases from the authors' institution have been used for illustration. SPECT-CT is a technology with emerging applications that offers technical advantages to image fusion of separately acquired SPECT and CT studies. The prevailing evidence indicates that there may be benefit in adding SPECT-CT to conventional imaging algorithms during the evaluation of some malignant and benign musculoskeletal conditions. SPECT-CT can improve both sensitivity and specificity by reducing equivocal interpretation in comparison to planar scintigraphy or SPECT alone. The evidence base for SPECT-CT in musculoskeletal radiology is still evolving. There is a lack of evidence comparing SPECT-CT with MRI in many key indications, and further research is required in these areas.

4D-SPECT/CT in orthopaedics: a new method of combined quantitative volumetric 3D analysis of SPECT/CT tracer uptake and component position measurements in patients after total knee arthroplasty

OBJECTIVE

The purpose was to evaluate the intra- and inter-observer reliability of combined quantitative 3D-volumetric single-photon emission computed tomography (SPECT)/CT analysis including size, intensity and localisation of tracer uptake regions and total knee arthroplasty (TKA) position.

MATERIALS AND METHODS

Tc-99m-HDP-SPECT/CT of 100 knees after TKA were prospectively analysed. The anatomical areas represented by a previously validated localisation scheme were 3D-volumetrically analysed. The maximum intensity was recorded for each anatomical area. Ratios between the respective value and the mid-shaft of the femur as the reference were calculated. Femoral and tibial TKA position (varus-valgus, flexion-extension, internal rotation- external rotation) were determined on 3D-CT. Two consultant radiologists/nuclear medicine physicians interpreted the SPECT/CTs twice with a 2-week interval. The inter- and intra-observer reliability was determined (ICCs). Kappa values were calculated for the area with the highest tracer uptake between the observers.

RESULTS

The measurements of tracer uptake intensity showed excellent inter- and intra-observer reliabilities for all regions (tibia, femur and patella). Only the tibial shaft area showed ICCs <0.89. The kappa values were almost perfect (0.856, p < 0.001; 95 % CI 0.778, 0.922). For measurements of the TKA position, there was strong agreement within and between the readings of the two observers; the ICCs for the orientation of TKA components for inter- and intra-observer reliability were nearly perfect (ICCs >0.84).

CONCLUSION

This combined 3D-volumetric standardised method of analysing the location, size and the intensity of SPECT/CT tracer uptake regions ("hotspots") and the determination of the TKA position was highly reliable and represents a novel promising approach to biomechanics.

Prosthetic vascular graft infection imaging

PURPOSE

We are reporting our experience with imaging of vascular graft infections using computed tomography angiography (CTA), white blood cell (WBC) scintigraphy and software-based fusion imaging.

MATERIAL AND METHODS

Institutional review board approval was obtained. We performed a retrospective review of patients who had clinical signs and symptoms of vascular graft infection in whom both WBC single photon emission computed tomography (SPECT) and CTA was performed between 2005 and 2010. We performed fusion imaging with available data using software coregistration technique and analyzed outcome of the patients.

RESULTS

We had 20 patients; 11 had grafts of the aorta, five had peripheral vascular grafts, three had aortic and peripheral vascular grafts, and one had a thoracic aortic graft. WBC imaging was positive in 10 patients, negative in six patients and indeterminate in 4 patients. CTA was positive in six patients, negative in four patients and indeterminate in 10 patients. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value (NPV) for WBC, CTA and WBC SPECT/CTA fusion were 75/100/80/100/50%, 88/50/80/88/50% and 94/50/85/88/67% respectively.

CONCLUSION

The use of CTA, WBC scintigraphy, and image co-registration influenced the diagnostic confidence of graft infection and the outcome of the patients. Software-based fusion imaging of both modalities resulted in improved sensitivity, accuracy, and NPV.

Efficacy of ⁹⁹mTc-sestamibi SPECT/CT for minimally invasive parathyroidectomy: comparative study with ⁹⁹mTc-sestamibi scintigraphy, SPECT, US and CT

PURPOSE

We evaluated the efficacy of (99m)Tc-sestamibi SPECT/CT for planning minimally invasive parathyroidectomy (MIP), comparing with dual phase (99m)Tc-sestamibi scintigraphy, (99m)Tc-sestamibi SPECT and conventional imaging (US and CT).

METHODS

Thirty-one patients (M:F = 10:21, range 35-78 years old) who showed high serum parathyroid hormone (intact PTH) level were included. (99m)Tc-sestamibi scintigraphy was performed 15 and 150 min after injection of (99m)Tc-sestamibi (555 MBq), and (99m)Tc-sestamibi SPECT/CT was obtained just after the delayed scan. Comparison study between imaging modalities was done by patient-based and lesion location-based analysis. The location of the lesion was confirmed by the operative finding. An operation was performed in 24 patients. Seven patients had normal (99m)Tc-sestamibi SPECT/CT, and followed for more than 6 months after SPECT/CT.

RESULTS

Among 24 patients, parathyroid adenoma was detected in 19 patients and the other 5 had parathyroid hyperplasia (total 35 lesions). (99m)Tc-sestamibi scintigraphy detected abnormal uptake in 15 patients with 24 lesions. Conventional imaging identified abnormal findings in 17 patients with 27 lesions. SPECT detected abnormal findings in 18 patients with 27 lesions. SPECT/CT identified abnormal findings in 24 patients with 35 lesions. SPECT/CT demonstrated 100 % sensitivity in a patient-based analysis. SPECT/CT exhibited significantly better sensitivity than (99m)Tc-sestamibi scintigraphy, SPECT and conventional imaging (p < 0.05). All lesion location was correctly identified to perform MIP. The final clinical diagnosis of 7 normal SPECT/CT patients was secondary hyperparathyroidism on 6 months follow-up.

CONCLUSIONS

We correctly identified the precise location of parathyroid adenomas or hyperplasia by (99m)Tc-sestamibi SPECT/CT which was helpful to perform MIP.

Soft Tissue Attenuation Patterns Associated with Supine Acquisition SPECT Myocardial Perfusion Imaging: A Descriptive Study

Purpose:

Soft-tissue attenuation patterns in SPECT-myocardial perfusion imaging (MPI) of supine acquisition systems are well recognized. Their prevalence and interaction with body-habitus and gender are ill-defined, which we sought to describe in this study.

Methods:

In a cross-sectional study, we described the prevalence of soft-tissue attenuation patterns in normal SPECT-MPI studies acquired with a supine patient-position SPECT system.

Results:

In 263 normal, clinically-indicated, supine-acquisition SPECT-MPIs the attenuation patterns observed were: anterior (35.4%), inferior (41.8%) and lateral (13.3%). Anterior attenuation was more prevalent among women (50.7% vs. 15.7%, P<0.001) and was associated with chest circumference among men. Conversely, inferior attenuation was more prevalent among men (78.3% vs. 13.5%, P<0.001) and was not affected by body-habitus. Lateral attenuation was more common among women (19.6% vs. 5.2%, p=0.001) and was associated with obesity (p=0.015).

Conclusions:

Soft-tissue attenuation artifacts are common in supine-acquisition SPECT-MPI. The recognition of their prevalence and association with body-habitus and gender is critical for the accurate interpretation of SPECT-MPI.

Standardized volumetric 3D-analysis of SPECT/CT imaging in orthopaedics: overcoming the limitations of qualitative 2D analysis

Background

SPECT/CT combines high resolution anatomical 3D computerized tomography (CT) and single photon emission computerized tomography (SPECT) as functional imaging, which provides 3D information about biological processes into a single imaging modality. The clinical utility of SPECT/CT imaging has been recognized in a variety of medical fields and most recently in orthopaedics; however, clinical adoption has been limited due to shortcomings of analytical tools available. Specifically, SPECT analyses are mainly qualitative due to variation in overall metabolic uptake among patients. Furthermore, most analyses are done in 2D, although rich 3D data are available. Consequently, it is difficult to quantitatively compare the position, size, and intensity of SPECT uptake regions among patients, and therefore difficult to draw meaningful clinical conclusions.

Methods

We propose a method for normalizing orthopaedic SPECT/CT data that enables standardised 3D volumetric quantitative measurements and comparison among patients. Our method is based on 3D localisation using clinically relevant anatomical landmarks and frames of reference, along with intensity value normalisation using clinically relevant reference regions. Using the normalised data, we describe a thresholding technique to distinguish clinically relevant hot spots from background activity.

Results

Using an exemplar comparison of two patients, we demonstrate how the normalised, 3D-rendered data can provide a richer source of clinical information and allow quantitative comparison of SPECT/CT measurements across patients. Specifically, we demonstrate how non-normalized SPECT/CT analysis can lead to different clinical conclusions than the normalized SPECT/CT analysis, and that normalized quantitative analysis can be a more accurate indicator of pathology.

Conclusions

Conventional orthopaedic frames of reference, 3D volumetric data analysis and thresholding are used to distinguish clinically relevant hot spots from background activity. Our goal is to facilitate a standardised approach to quantitative data collection and comparison of clinical studies using SPECT/CT, enabling more widespread clinical use of this powerful imaging tool.

Radiotracers for SPECT imaging: current scenario and future prospects

Single photon emission computed tomography (SPECT) has been the cornerstone of nuclear medicine and today it is widely used to detect molecular changes in cardiovascular, neurological and oncological diseases. While SPECT has been available since the 1980s, advances in instrumentation hardware, software and the availability of new radiotracers that are creating a revival in SPECT imaging are reviewed in this paper.

The biggest change in the last decade has been the fusion of CT with SPECT, which has improved attenuation correction and image quality. Advances in collimator design, replacement of sodium iodide crystals in the detectors with cadmium zinc telluride (CZT) detectors as well as advances in software and reconstruction algorithms have all helped to retain SPECT as a much needed and used technology.

Today, a wide spectrum of radiotracers is available for use in cardiovascular, neurology and oncology applications. The development of several radiotracers for neurological disorders is briefly described in this review, including [123I]FP-CIT (DaTSCANTM) available for Parkinson's disease. In cardiology, while technetium-99m labeled tetrofosmin and technetium-99m labeled sestamibi have been well known for myocardial perfusion imaging, we describe a recently completed multicenter clinical study on the use of [123I]mIBG (AdreViewTM) for imaging in chronic heart failure patients. For oncology, while bone scanning has been prevalent, newer radiotracers that target cancer mechanisms are being developed. Technetium-99m labeled RGD peptides have been reported in the literature that can be used for imaging angiogenesis, while technetium-99m labeled duramycin has been used to image apoptosis.

While PET/CT is considered to be the more advanced technology particularly for oncology applications, SPECT continues to be the modality of choice and the workhorse in many hospitals and nuclear medicine centers. The cost of SPECT instruments also makes them more attractive in developing countries where the cost of a scan is still prohibitive for many patients.

Combined single photon emission computerized tomography and conventional computerized tomography: Clinical value for the shoulder surgeons?

With the cases described, we strive to introduce single photon emission computerized tomography in combination with conventional computer tomography (SPECT/CT) to shoulder surgeons, illustrate the possible clinical value it may offer as new diagnostic radiologic modality, and discuss its limitations. SPECT/CT may facilitate the establishment of diagnosis, process of decision making, and further treatment for complex shoulder pathologies. Some of these advantages were highlighted in cases that are frequently seen in most shoulder clinics.