Utility of I-124 PET/CT in identifying radioiodine avid lesions in differentiated thyroid cancer: a systematic review and meta-analysis.

INTRODUCTION: Diagnostic I-123 scans have been shown to underestimate the disease burden in differentiated thyroid cancer (DTC) when compared to I-131 post-treatment scans, especially in children and patients who have had prior radioiodine (RAI) therapy and/or distant metastasis. I-124 PET/CT has been shown to be highly effective in imaging DTC-related metastatic disease. METHODS: We performed a systematic review and meta-analysis of studies investigating the sensitivity and specificity of I-124 PET/CT in identifying lesions amenable to RAI therapy as confirmed by I-131 post-treatment scanning. RESULTS: There were 141 patients and 415 lesions of DTC identified altogether. There was significant heterogeneity in the individual studies. The pooled sensitivity of the I-124 PET/CT in detecting lesions of differentiated thyroid cancer amenable to I-131 therapy was 94·2% (91·3-96·4% CI, P < 0·01), and the pooled specificity was 49·0% (34·8-63·4% CI, P < 0·01). The pooled positive likelihood ratio (LR) was 1·43 (1·05-1·94 CI), and the pooled negative LR was 0·28 (0·15-0·53 CI). Overall, the diagnostic odds ratio was 7·90 (3·39-18·48 CI). There were a small but increased number of lesions identified by I-124 PET/CT that was not detected on post-treatment scan. CONCLUSION: I-124 PET/CT is a sensitive tool to diagnose RAI avid DTC lesions, but also detects some new lesions that are not visualized on the post-treatment I-131 scan. Further, carefully designed dosimetric studies may be required to fully establish the role of I-124 PET CT for identifying potential lesions for I-131 therapy. I-124 PET/CT in patients with DTC may have other applications in specific clinical situations.

JOURNAL CLUB: Value of Quantitative FDG PET/CT Volumetric Biomarkers in Recurrent Colorectal Cancer Patient Survival.

OBJECTIVE: The purpose of this study was to evaluate the impact of quantitative PET parameters in the overall survival of patients with recurrent colorectal cancer. MATERIALS AND METHODS: A total of 105 patients with a biopsy-proven recurrence of colorectal cancer who underwent PET/CT were included in the study. A gradient segmentation method was used to calculate maximum and peak standardized uptake values (SUVmax, SUVpeak), total lesion glycolysis (TLGtotal), and metabolic tumor volume (MTVtotal). These parameters were measured for each recurrent lesion at the primary, locoregional, and distant sites. The median follow-up time was 31.3 months. Overall survival (OS) was the primary outcome and was calculated using Kaplan-Meier survival plots and Cox regression analyses. RESULTS: The mean ± SD for SUVmax, SUVpeak, TLGtotal, and MTVtotal of the included patients was 7.3 ± 5.3, 5.3 ± 3.3, 280.8 ± 1181 g, and 79.8 ± 294 mL, respectively. The median OS for patients who were alive was 50 months in comparison with 23.4 months among patients who died. Age (p = 0.041), tumor grade (p = 0.010), median TLG (p = 0.031), and median MTV (p = 0.009) remained significantly associated with OS in the multivariate Cox regression analysis. Kaplan-Meier survival analysis performed on the basis of the median PET/CT parametric values showed that SUVmax (threshold, 5.63; hazard ratio [HR] = 1.7; 95% CI, 1-2.8; p = 0.02), MTVtotal (threshold, 13.85 mL; HR = 2.2; 95% CI, 1.3-3.9; p = 0.003), and TLGtotal (threshold, 36.14 g; HR = 1.9; 95% CI, 1.1-3.3; p = 0.01) were significant predictors of OS during follow-up. An integrated risk stratification model with SUVmax and MTVtotal into three subgroups predicted patient survival outcomes (HR = 1.8; 95% CI, 1.25-2.65; log-rank p = 0.003). CONCLUSION: SUVmax, MTVtotal, TLGtotal, and integrated score with FDG avidity and total tumor burden provide survival information for patients with biopsy-proven recurrent colorectal cancer.

Quantitative parameters for diagnosis of idiopathic intracranial hypertension on brain MRI.

PURPOSE: Aim of this study was to develop quantitative parameters for diagnosing Idiopathic Intracranial Hypertension (IIH) using brain MRI scans. METHODS: This is a case control study with 48 cases and 192 matched controls. Optic nerve diameter (OND), Pituitary height (PH), Meckel's cave diameter (MCD), and Neck fat thickness (NFT) were measured for both groups. Consequently, means were obtained for the different parameters in both groups with subsequent establishment of best cutoffs using Receiver Operator Curve (ROC) analysis. RESULTS: For IIH patients the means of OND, PH, MCD, and NFT were 6.2 mm, 3.9 mm, 5 mm, 1.4 cm, respectively while for controls the means were 4.6 mm, 4.5 mm, 4.3 mm, and 0.8 cm with statistical significance between the two groups. ROC analysis showed the cutoff points with best accuracy for the above parameters in diagnosing IIH to be 5.4 mm for OND with sensitivity of 0.77 and specificity of 0.85 representing high accuracy, while for PH a cutoff point of 3 mm showed low accuracy with sensitivity of 0.54 and specificity of 0.7, and a MCD cutoff of 4.5 mm also showed low accuracy with sensitivity of 0.6 and specificity of 0.59, meanwhile a cutoff point of 1.1 cm for NFT was moderately accurate with sensitivity of 0.70 and specificity of 0.81. CONCLUSION: Statistical difference in the means for OND, PH, MCD, and NFT between IIH patients and controls is established. Also, we provide cut off points for these parameters to diagnose IIH on brain MRI.

Morphometric study of foramina transversaria in Jordanian population using cross-sectional computed tomography.

Foramina transversaria are bilateral landmarks of human cervical vertebrae. Morphometric analysis of foramina transversaria is valuable in both clinical and academic fields. This study aims to build a novel normative database of the dimensions of foramina transversaria in Jordanian population and to correlate these data with gender and age. For this purpose, axial computer tomographic images of cervical vertebrae of 329 normal individuals were obtained from the Radiology Department at King Abdulla University Hospital. Cases were subdivided into adolescence, youth, and adulthood groups for both genders. Antero-posterior and transverse diameters were measured bilaterally at all cervical vertebral levels. Statistical analysis of measured dimensions was performed using Statistical Package of Social Sciences software. The results showed that the overall mean antero-posterior diameter of foramina transversaria was 6.09 ± 0.60mms and 5.94 ± 0.62mms on the left and on the right sides, respectively. The corresponding mean transverse diameter measured 4.76 ± 0.51mms and 4.62 ± 0.52mms on the left and the right sides, respectively. Foramina transversaria were significantly larger in males compared to females (p = 0.00). Age-related differences were statistically significant for both antero-posterior and transverse diameters in favor of adult age-group, irrespective of vertebral level. The relevance of these findings is discussed.

Ankylosing Spondylitis With Bilateral Symmetrical Uptake in the Greater Trochanters on Bone Scan.

Ankylosing spondylitis is a chronic inflammatory bone disease that commonly affects the spine and the sacroiliac joints. Ankylosing spondylitis can also cause enthesitis, or enthesopathy, which is an inflammation at the tendinous or ligamentous insertion sites on the bones. In this study, we present the case of a 37-year-old man with ankylosing spondylitis with a unique Tc-HDP bone scan finding of symmetrical increased uptake bilaterally in the greater trochanters.

A physics-guided modular deep-learning based automated framework for tumor segmentation in PET.

An important need exists for reliable positron emission tomography (PET) tumor-segmentation methods for tasks such as PET-based radiation-therapy planning and reliable quantification of volumetric and radiomic features. To address this need, we propose an automated physics-guided deep-learning-based three-module framework to segment PET images on a per-slice basis. The framework is designed to help address the challenges of limited spatial resolution and lack of clinical training data with known ground-truth tumor boundaries in PET. The first module generates PET images containing highly realistic tumors with known ground-truth using a new stochastic and physics-based approach, addressing lack of training data. The second module trains a modified U-net using these images, helping it learn the tumor-segmentation task. The third module fine-tunes this network using a small-sized clinical dataset with radiologist-defined delineations as surrogate ground-truth, helping the framework learn features potentially missed in simulated tumors. The framework was evaluated in the context of segmenting primary tumors in 18F-fluorodeoxyglucose (FDG)-PET images of patients with lung cancer. The framework's accuracy, generalizability to different scanners, sensitivity to partial volume effects (PVEs) and efficacy in reducing the number of training images were quantitatively evaluated using Dice similarity coefficient (DSC) and several other metrics. The framework yielded reliable performance in both simulated (DSC: 0.87 (95% confidence interval (CI): 0.86, 0.88)) and patient images (DSC: 0.73 (95% CI: 0.71, 0.76)), outperformed several widely used semi-automated approaches, accurately segmented relatively small tumors (smallest segmented cross-section was 1.83 cm2), generalized across five PET scanners (DSC: 0.74 (95% CI: 0.71, 0.76)), was relatively unaffected by PVEs, and required low training data (training with data from even 30 patients yielded DSC of 0.70 (95% CI: 0.68, 0.71)). In conclusion, the proposed automated physics-guided deep-learning-based PET-segmentation framework yielded reliable performance in delineating tumors in FDG-PET images of patients with lung cancer.

Pitfalls and value of organ specific approach in evaluating indeterminate lesions detected on CT in colorectal cancer by [F18] FDG PET/CT.

OBJECTIVE: The objective of this study is to evaluate the value of FDG PET/CT for different involved organs showing Indeterminate/ equivocal / suspicious lesions detected on IV contrasted CT during surveillance follow up for colorectal cancer. MATERIALS AND METHODS: A total of 67 patients with colorectal cancer how are on regular surveillance follow up by IV contrasted CT scans revealing indeterminate lesions were studied. Subsequent FDG PET/CT evaluation was performed as a problem solving modality. PET/CT results were statistically characterized when compared to biopsy results or to follow/up results. Also Statistical parameters were calculated for each organ involved. The evaluation of all CT indeterminate lesions by FDG PET/CT showed overall sensitivity of 93%, Specificity of 81%, Negative predictive value of 94%, Positive predictive value 80% and accuracy of 87%. However in an organ specific approach the highest accuracy was for lymph nodes with results showing a 100% accuracy and the lowest accuracy was for local disease at a value of 80%. Probable explanations for the falsely characterized lesions resulting in the pitfalls seen and in the imperfect accuracy were provided. CONCLUSION: Study shows that FDG PET/CT is an excellent tool in characterizing CT indeterminate lesions during surveillance of colorectal cancer, However different organs showed variable accuracy results with the highest accuracy for our study was for lymph node status (100%) and the lowest accuracy being for local disease at the original site of primary tumor (80%).

Functional Imaging of Evaluation of Diabetic Gastroparesis.

INTRODUCTION: Gastroparesis (a complication of both type 1 and type 2 diabetes mellitus) is delayed gastric emptying in the absence of a mechanical obstruction. Overall prevalence of Gastroparesis is close to 5 % in type 1 diabetes and 1 % in type 2 diabetes. It is unclear if good glycemic control leads to the delay of development and progression of gastroparesis. METHODS: Gastric enteric neurons as well as Interstitial Cells of Cajal (ICC) are depleted, truncated and are surrounded by immune infiltrates composed of macrophages. There are associated vagal nerve innervation abnormalities, smooth muscle and Fibroblast Like Cell (FLC) dysfunctions. There is s decrease in HO-1 macrophages and increase in proinflammatory macrophages. Gastric electrical rhythm abnormalities and channelopathies have been implicated in the pathology of gastrointestinal diseases. RESULTS: In patients with diabetes, the most common clinical symptoms include abdominal bloating and pain. Nuclear Medicine Gastric Emptying Scintigraphy (NMGES) is considered the gold standard for evaluation of gastroparesis. Conventional imaging techniques such as fluoroscopic evaluation of gastric emptying can only evaluate the presence or absence of an obstruction. Historically, solid gastric emptying has been the method for evaluation although recent data suggests that liquid gastric emptying may be altered without solid gastric emptying abnormality. It is paramount that a radiotracer for evaluating gastric emptying be tightly bound to ingested food (solid). The most frequent radiotracer used is Tc99msulfur colloid bound to egg whites. In an effort to standardize normal values across institutions, a consensus recommendation published in 2008 called for a 4- hour study utilizing a standardized meal. CONCLUSION: Nuclear Medicine Gastric Emptying Scintigraphy (NMGES) is the test of choice for evaluation of diabetic gastroparesis. Standard guidelines have been established for the performance and interpretation of the test.

Impact of DAT-SPECT on Management of Patients Suspected of Parkinsonism.

OBJECTIVE: To evaluate the value of I-2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (I-FP-CIT) dopamine transporter single photon emission computed tomography (DAT-SPECT) to change management strategies of patients suspected of parkinsonism. METHOD: This was an institutional review board-approved, retrospective study. DAT-SPECT scans ordered by movement disorder specialist and neurologists from 2011-2014 were reviewed. Clinical data and radiological reports of 173 patients suspected of parkinsonism were reviewed. The DAT-SPECT scan results were correlated with clinical assessment and treatment changes. RESULTS: A total of 173 patients (104 male and 69 female subjects; age, 64.4 ± 12.6 years) suspected of parkinsonism were included. Median duration of symptoms was 36 months (range, 1-480 months). Scans were most often requested when there was diagnostic uncertainty in clinical features (59.6%, 103/173) or to differentiate one other disease from parkinsonism such as Parkinson disease (PD) versus essential tremor (23.7%, 41/173), PD versus drug-induced parkinsonism (8.7%, 15/173), or PD versus psychogenic (6.4%, 11/173) or vascular (1.7%, 3/173) disorders. Patients were classified, according to the DAT-SPECT scanning results, as those with abnormal DAT-SPECT findings (59%, 102/173) and those with normal DAT-SPECT findings (41%, 71/173). In patients with normal DAT-SPECT findings, follow-up management data were available in 76.1% (54/71). The management changed in 39.4% (28/54) after DAT scan with starting a new appropriate medications or supportive therapy in 4.2% (3/28), withholding inappropriate dopaminergic treatment in 11.3% (8/28), or continuing observation in 23.9% (17/28). In patients with abnormal DAT-SPECT findings, follow-up management data were available in 78.4% (80/102). There was change in management of 37.3% (38/80), a new PD treatment was started in 89.5% (34/38). The dose of medication was adjusted in 5.3% (2/38), although the original treatment was not changed. Parkinson disease treatment was stopped in 2.6% (1/38) and discontinued in 2.6% (1/38) based on clinical decision of neurologists despite abnormal DAT-SPECT findings. CONCLUSIONS: DAT-SPECT findings impacted treatment decisions in 44.7% of patients suspected of Parkinsonism.

Magnetic resonance elastography to estimate brain stiffness: Measurement reproducibility and its estimate in pseudotumor cerebri patients.

This study determines the reproducibility of magnetic resonance elastography (MRE) derived brain stiffness in normal volunteers and compares it against pseudotumor patients before and after lumbar puncture (LP). MRE was performed on 10 normal volunteers for reproducibility and 14 pseudotumor patients before and after LP. During LP, opening and closing cerebrospinal fluid (CSF) pressures were recorded before and after removal of CSF and correlated to brain stiffness. Stiffness reproducibility was observed (r > 0.78; p < 0.008). Whole brain opening LP stiffness was significantly (p = 0.04) higher than normals, but no significant difference (p = 0.11) in closing LP measurements. No significant correlation was observed between opening and closing pressure and brain stiffness.

PET-measured longitudinal flow gradient correlates with invasive fractional flow reserve in CAD patients.

AIMS: We aimed to evaluate whether a PET-determined longitudinal decrease in myocardial blood flow (MBF) or gradient, assumed as a more specific flow parameter for epicardial resistance, correlates with invasively measured fractional flow reserve (FFR) in coronary artery disease (CAD) patients. METHODS AND RESULTS: In 29 patients with suspected or known CAD, myocardial perfusion and MBF in mL/g/min was determined with 13N-ammonia PET/CT during regadenoson stimulation and at rest, and corresponding myocardial flow reserve (MFR = MBF stress/MBF rest) was calculated. MBF parameters were assessed in the myocardial region with stress-related perfusion defect and with stenosis ≥50% (Region 1), without defect but with stenosis ≥50% (Region 2), or without stenosis ≥50% (Region 3). Hyperaemic MBFs were significantly lower in the mid-distal than in the mid-left ventricular myocardium in Regions 1-3 [median and IQ range: 1.57 (1.24, 1.84) vs. 1.87 (1.61, 2.00), and 1.23 (1.11, 1.86) vs. 1.89 (1.80, 1.97), and 1.78 (1.48, 2.00) vs. 1.94 (1.84, 2.05) mL/g/min, P < 0.0001]. Resulting longitudinal MBF gradient during hyperaemic flows was more pronounced in Region 2 than in Regions 1 and 3, respectively [-0.46 (-0.70, -0.10) vs. -0.17 (-0.29, -0.11) and -0.15 (-0.25, -0.09) mL/g/min, respectively, P < 0.01]. There was a significant correlation between the hyperaemic longitudinal MBF gradient and FFR (r = 0.95; P < 0.0001), while this association was less pronounced for corresponding MFR (r = 0.50; P = 0.006). CONCLUSION: The observed close correlation between a longitudinal MBF gradient during hyperaemic flows and invasively measured FFR suggests the longitudinal flow gradient as an emerging non-invasive index of flow-limiting CAD.

Uptake of the prostate-specific membrane antigen-targeted PET radiotracer 18F-DCFPyL in elastofibroma dorsi.

OBJECTIVE: PET imaging using radiotracers that target prostate-specific membrane antigen (PSMA) are increasingly being used in the evaluation of men with prostate cancer (PCa). It is therefore of increasing importance for imaging specialists to recognize potential pitfalls of this novel imaging technique. In this report, we describe a series of benign elastofibroma dorsi with uptake of the PSMA-targeted PET radiotracer F-DCFPyL. PATIENTS AND METHODS: We retrospectively analyzed the imaging data of 75 men with PCa who were consecutively imaged with F-DCFPyL PET/CT. Acquired images were reviewed for the presence of radiotracer uptake in the region of the scapular tip adjacent to the chest wall. Only those lesions with discrete radiotracer uptake corresponding to an area on CT with the characteristic appearance of an elastofibroma were considered positive. RESULTS: In total, 18/75 (24.0%) patients had evidence of at least one elastofibroma dorsi on F-DCFPyL PET/CT. Eight (44.4%) of these patients had unilateral lesions, all of which were right sided. Detected lesions had a median maximal diameter of 2.3 cm (range: 1.3-8.4 cm) and a median perpendicular thickness to the chest wall of 0.9 cm (range: 0.6-2.5 cm). The median maximum standardized uptake value of detected lesions was 1.4 (range: 1.1-2.4) and the median maximum standardized uptake value corrected to lean body mass was 1.1 (range: 0.8-1.7). CONCLUSION: This study is the first to report uptake of a PSMA-targeted PET radiotracer in elastofibroma dorsi. Radiotracer uptake in these benign lesions should not be falsely mistaken as sites of metastatic PCa.

Potential Role of Cardiovascular Imaging in Improving Cardiovascular Outcome in Coronary Artery Disease.

BACKGROUND: There is increasing interest in cardiovascular imaging modalities in the detection of subclinical and clinically-manifested coronary artery disease (CAD) to improve cardiovascular outcome in these patients. METHODS: SPECT/CT and PET/CT can be applied for the assessment of myocardial perfusion and myocardial blood flow (MBF) quantification in CAD detection and characterization, while CT is predominantly used to identify coronary plaque burden and epicardial narrowing. In addition, PET/CT plays an increasing role in the detection of the "vulnerable" plaque in the epicardial artery. RESULTS: Imaging of myocardial perfusion with SPECT, SPECT/CT and PET/CT is a mainstay in clinical practice for the identification of flow-limiting epicardial lesions and risk stratification of patients with suspected or known CAD. In this direction, the concurrent ability of PET/CT to determine regional myocardial blood flow (MBF) in ml/g/min at rest and during pharmacologically- induced hyperemic flows allows the calculation of the myocardial flow reserve (MFR) that may unravel reductions in coronary vasodilator capacity, as functional precursor of the CAD process, monitor its response to preventive medical intervention, yield important prognostic information in subclinical - and clinically-manifested CAD, and contributes to identify the flow-limiting effect of single lesions in multivessel CAD. Adding noncontrast computed-tomography (CT) measurements of coronary artery calcifications has further improved the reclassification of cardiovascular risk in asymptomatic individuals with intermediate probability of the presence of CAD. With contrast CT, the non-invasive visualization of coronary vessels, CAD-related plaque burden and stenosis has become feasible. Yet, a definite identification of the "vulnerable plaque" is still a matter of ongoing research. PET/CT in conjunction with various positron-emitting radiotracer yields promise in the detection of the "vulnerable plaque," that, however, needs further clinical evaluation in CAD patients. CONCLUSION: Multimodality imaging in cardiovascular disease is likely to further advances and refine the identification and characterization of cardiovascular pathology in the near future.

Use of 18F-Fludeoxyglucose-Positron Emission Tomography/Computed Tomography for Patient Management and Outcome in Oropharyngeal Squamous Cell Carcinoma: A Review.

18F-fludeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) has been performed widely in diagnosis and management of patients with oropharyngeal squamous cell carcinoma (OPSCC). This review summarizes the literature on this tool in the management of these patients. The use of FDG-PET/CT helps in accurate staging of primary tumor, nodal involvement, and distant metastasis of patients with OPSCC. Contrast-enhanced FDG-PET/CT combines high-resolution CT and functional FDG-PET, providing the optimum imaging information for patient management. Using contrast-enhanced PET/CT leads to a combined anatomic and metabolic approach to radiation therapy planning in OPSCC. Moreover, PET/CT not only is a good modality for therapy assessment but also is a powerful tool in early recurrence detection of OPSCC. Finally, the PET/CT parameters provide survival information in patients with OPSCC; however, further studies are needed to introduce a scoring system to use clinically for prognosis prediction.

Case Report: Brown Fat Accumulation of Tc-99m Macroaggregated Albumin in a Lung Perfusion Study in a Patient With Multiple Lung Arteriovenous Malformations and Right-to-Left Shunting.

An 18-year-old man was preoperatively assessed for a varicocele and found to be hypoxemic. A Tc-99m macroaggregated albumin lung perfusion scan showed right-to-left shunting, evidenced by increased radiotracer uptake in the brain, kidneys, thyroid gland, and bilateral supraclavicular areas, a typical location for brown adipose tissue. Chest computerized tomography angiogram study showed supraclavicular fat density areas and multiple pulmonary arteriovenous malformations.The authors report a rare case of brown fat visualization on a lung perfusion scan in a patient with right-to-left shunting, likely because of increased perfusion to activated brown adipose tissue.

¹8F-FDG PET/CT and Colorectal Cancer: Value of Fourth and Subsequent Posttherapy Follow-up Scans for Patient Management.

UNLABELLED: The purpose of this study was to evaluate the added value of a fourth and subsequent follow-up PET/CT scans to clinical assessment and impact on patient management in patients with colorectal cancer. METHODS: This was an institutional review board-approved, retrospective study. Eight hundred twenty-two patients with biopsy-proven colorectal cancer, who underwent (18)F-FDG PET/CT, were identified from 2000 to 2012. Among these, 73 (8.9%) patients underwent 4 or more follow-up PET/CT scans, with a total of 313 fourth and subsequent follow-up PET/CT scans. Median follow-up from the fourth follow-up PET/CT scan was 41.7 mo. The added value of each follow-up PET/CT scan, for clinical assessment and the treatment changes subsequent to each follow-up PET/CT scan, was established. Overall survival prediction was established using Kaplan-Meier plots with a Mantel-Cox log-rank test. RESULTS: Of the 313 fourth and subsequent follow-up PET/CT scans, 174 (55.6%) were interpreted as positive and 139 (44.4%) were interpreted as negative for recurrence or metastases. Thirty-four (46.6%) patients died during the study period. PET/CT identified recurrence or metastasis in 40.0% of scans obtained without prior clinical suspicion and ruled out disease in 23.6% of scans obtained with prior clinical suspicion. The PET/CT scan resulted in treatment change after 34.2% (107/313) of the scans. New treatment was initiated after 24.0% (75/313) of the scans, and treatment was changed after 8.0% (25/313) scans. There was a statistically significant difference in the overall survival between patients with a positive and all negative fourth and subsequent follow-up PET/CT scans at the patient level (log-rank, P = 0.001). CONCLUSION: The fourth and subsequent (18)F-FDG PET/CT scans obtained after primary treatment completion add value to clinical assessment and the management plan and provide prognostic information in patients with colorectal cancer.