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Clinical Nuclear Medicine - Current Issue

Clinical Nuclear Medicine - Current Issue
  1. Cardiac Fibroma: An Uncommon Cause of a Fixed Defect on Myocardial Perfusion Imaging
    imageA 66-year-old woman was referred for evaluation of coronary artery disease. Myocardial perfusion imaging (MPI) was performed, and showed a medium-sized, severe fixed perfusion defect in the inferior and inferolateral wall from apex to midcavity. On review of prior imaging, it was noted that the patient had an incidental finding of an intramural cardiac mass on chest CT performed 8 years prior. Subsequent cardiac MRI showed findings consistent with a cardiac fibroma in the left ventricle, at the location of the perfusion defect on MPI. Our case demonstrates an uncommon cause of a fixed perfusion defect on MPI.



  2. A Novel Technique to Measure the Intensity of Abnormality on GI Bleeding Scans: Development, Initial Implementation, and Correlation With Conventional Angiography
    imagePurpose Develop a technique to quantify intensity of lower gastrointestinal bleeding (LGIB) on 99mTc-labeled red blood cell (RBC) scintigraphy, correlate with angiography, and determine the tool’s predictive value. Materials and Methods An IRB-approved, single institution database query of GI bleeding scans performed between January 2013 and December 2015. Reports from all studies and imaging from all positive studies were reviewed. A technique was developed for scan analysis, allowing for calculation of percent increase of activity in the region of interest (ROI, area of bleeding) and ROI in the aorta and liver (controls). Database query determined which patients underwent angiography, and which had positive angiograms. Median ROI percent increase in patients with positive scintigraphy and positive angiography was compared to those with positive scintigraphy and negative angiography. Results Of 194 bleeding scans performed during the study period, 71 were positive for active LGIB, 37 had angiography, and 9 had active contrast extravasation. The new tool was used to analyze the 37 cases with positive nuclear scans sent for angiography. Median percent increase in ROI activity was 50% in those with positive scan and positive angiogram and 26.8% in those with positive scan but negative angiogram. Using ROI percent change quartiles, we observed a statistically significant association between percent increase in ROI activity from baseline and the probability of having a positive angiogram (Cochran-Armitage trend test, P = 0.01), such that there are no positive angiogram cases when ROI change was <20% and a majority of the positive angiogram cases (67%) in the highest quartile. Conclusions Utilization of processing protocol to determine percent increase in activity from baseline within ROI of active LGIB on scintigraphy has predictive value in determining which patients will not benefit from conventional angiography.



  3. 123I-FP-CIT SPECT Accurately Distinguishes Parkinsonian From Cerebellar Variant of Multiple System Atrophy
    imagePurpose Dopamine transporter SPECT imaging is a valuable tool to estimate the integrity of presynaptic dopaminergic pathways in degenerative parkinsonisms. Evidence about SPECT differential pattern between parkinsonian and cerebellar forms of multiple system atrophy (MSA-P and MSA-C) is lacking. We aimed at assessing whether MSA-P and MSA-C variants have a distinct semiquantitative 123I-FP-CIT SPECT pattern. Methods We studied a unicentric 13-year (2003–2016) retrospective cohort of subjects with possible or probable MSA and scanned with the same acquisition and reconstruction SPECT protocol. Age-dependent semiquantitative reference limits for striatal volumes of interest, asymmetry indices, and caudate/putamen ratio were previously established with a percentile approach on a cohort of subjects with nondegenerative conditions and normal visual scan. Results Thirty-four subjects with clinical MSA (28 MSA-P and 6 MSA-C) were identified (mean age, 68.2 ± 10.1 years; male/female ratio 1.00; disease duration, 2.5 ± 2.2 years; Movement Disorders Society Unified Parkinson's Disease Rating Scale III score, 33.8 ± 12.4). The MSA-P subjects exhibited lower uptake values for all volumes of interest, for example, striatal uptake on the more affected side (1.10 ± 0.51) compared with MSA-C (2.30 ± 0.41, P = 0.0005), as well as significantly higher asymmetry indices % (24.7 ± 24.8 vs 6.3 ± 4.5, P = 0.028) and caudate/putamen ratio (2.26 ± 1.23 vs 1.13 ± 0.17, P = 0.00148). Conclusions The MSA-P and MSA-C subjects exhibited significantly distinct semiquantitative SPECT pattern with severe uptake impairment and high asymmetry for MSA-P and borderline uptake values for MSA-C. Clinical distinction of these 2 phenotypical entities is necessary in order to evaluate SPECT potential to discriminate between degenerative parkinsonisms.



  4. 18F-FDG PET/CT in Diagnostic and Prognostic Evaluation of Patients With Suspected Recurrence of Chondrosarcoma
    imagePurpose The aim of the study was to analyze the diagnostic and prognostic utility of 18F-FDG PET/CT to predict the disease-specific survival (DSS) with FDG uptake and tumor grade in recurrent chondrosarcoma. Methods Retrospective analysis of FDG PET/CT findings in 31 previously treated patients (46 studies) with mean follow-up period of 40.7 ± 23.9 months (range, 3–77 months) from the date of first PET/CT study was done. Kaplan-Meier DSS analysis was made with respect to tumor grade, FDG uptake at the recurrent primary sites, and a combination of grade and FDG uptake as parameters. Results Recurrence (local and distant) was shown in 28 (60.8%) of 46 FDG PET/CT studies with sensitivity and specificity of 88.9% and 78.9%, respectively. The median SUVmax at the recurrent primary sites differed significantly (P = 0.008) among 3 tumor grade groups, with higher median SUVmax in higher grades. There was significant difference in median SUVmax among different grade groups except between grade II and grade III. Recurrent primary site SUVmax cutoff at 6.15 derived from the receiver operating characteristic curve yielded significant difference (P < 0.001) in mean DSS time. Significant difference in survival was noted between 3 different tumor grade groups (P = 0.016). The combination of SUVmax and grade improved the survival prediction than with grade alone. Conclusions In recurrent chondrosarcoma, the recurrent primary site FDG uptake and grade were found to be reliable prognostic factors with respect to DSS. PET/CT in recurrence setting has the potential to predict tumor grade and survival and may assist in clinical management.



  5. False-Positive Heat-Damaged RBC Scan for Splenosis: Case of Retroperitoneal Extramedullary Hematopoiesis
    imageExtramedullary hematopoiesis (EMH) is a well-known compensatory response to severe anemia, most commonly due to a chronic hemolytic anemia such as thalassemia or sickle cell disease. We present a case of a 72-year-old man with autoimmune hemolytic anemia refractory to steroids and splenectomy. An incidental retroperitoneal mass on CT was suggestive of ectopic splenic tissue. However, an alternative diagnosis of EMH was considered, given an atypical appearance on heat-damaged 99mTc-RBC scan, and was confirmed with biopsy. The case report illustrates the imaging characteristics of EMH, widely known to have increased activity on 99mTc-sulfur colloid scans.


  6. SUV as a Possible Predictor of Disease Extent and Therapy Duration in Complex Tuberculosis
    imageObjective 18F-FDG PET/CT provides information on disease extension and activity in neoplastic and inflammatory conditions. So far, little is known about whether SUVmax of a reference lesion can allow a prognosis to be given regarding patient-specific outcome parameters in complex cases of tuberculosis (TB). Methods We retrospectively identified 37 patients (21 men, 16 women; mean age, 50.4 years) who underwent 18F-FDG PET/CT for the evaluation of active TB before treatment initiation. The aims were to examine whether the reference lesion SUVmax differed between patients with standard (≤9 months) and long-term (>9 months) therapy and to define an SUVmax cutoff distinguishing those groups. In addition, we analyzed the prognostic value of SUVmax with regard to estimation of initial disease extent and lesion distribution pattern. Results Median therapy duration was 10 months (interquartile range, 3.25 months), and median SUVmax was 8 (interquartile range, 8.54). SUVmax was significantly (P = 0.036) higher in patients treated longer than 9 months (10.1 vs 5.5). When applying a receiver operating characteristic curve analysis, an SUVmax cutoff value of 10 differentiated the standard and the long-term therapy group with a sensitivity of 50% and a specificity of 78.6% (P = 0.087). Higher SUVmax corresponded with a larger number of affected organ systems (P = 0.012 for ≤/>1). Patients with extrathoracic involvement showed significantly higher SUVmax than did patients with limited intrathoracic disease (P = 0.024) and received significantly longer antimycobacterial therapy (P = 0.011). Conclusions Reference lesion SUVmax from pretherapy 18F-FDG PET/CT may have prognostic properties in complicated cases of TB, especially regarding therapy duration and disease extent.



  7. Artifactual Hepatic Metastasis on FDG PET/CT Secondary to Cryoablation for Adrenal Metastasis
    imageA 65-year-old woman with metastatic lung cancer was referred for CT-guided cryoablation of a right adrenal metastasis. For cryoablation, probes were placed into the adrenal region. FDG PET/CT 3 months later showed new activity in hepatic segment 6 initially suspected to be metastasis. Proximity of the hepatic lesion to the adrenal metastasis was a strange coincidence and prompted review of imaging from the cryoablation. CT showed the probe entered the liver, and postablation image demonstrated injury to the liver adjacent to the adrenal metastasis. Careful review of treatment history and imaging from ablation procedures are important to avoid this pitfall.



  8. Quality and Safety in Health Care, Part XXXII: Additional Outcome Predictors for Transcatheter Aortic Valve Replacement
    Mortality 12 months after a transcatheter aortic valve replacement (TAVR) is partly due to a number of reasons in addition to the usual preprocedural medical patient risk factors. In patients who need a permanent pacemaker placed after the procedure, the mortality risk goes up. The death rate following a TAVR varies considerably at different institutions, and the past death rate of TAVR patients at an institution is predictive of the mortality rate of new patients having this procedure. In addition, the quality of life of the individual before the procedure is predictive of the 12-month mortality outcome after the TAVR is done.



  9. Subacute Cerebellar Infarction With Uptake on 68Ga–Prostate-Specific Membrane Antigen PET/CT
    imageWe report a case of subacute cerebellar infarction mimicking metastasis on prostate-specific membrane antigen (PSMA) PET/CT. A 77-year-old man with prostate cancer treated with androgen deprivation therapy and radiotherapy with rising prostate-specific antigen was referred for 68Ga-PSMA PET/CT. Apart from PSMA-expressing tumor of the left prostate, PSMA PET/CT demonstrated radiotracer uptake in the right cerebellar hemisphere, corresponding to a site of subacute infarction demonstrated on an MRI of the brain performed 35 days previously. As cerebellar infarcts are considerably less common than cerebral infarcts, they may not be anticipated as a potential cause for false-positive radiotracer uptake on PSMA PET.



  10. Imaging of Acquired Demyelinating Syndrome With 18F-FDG PET/CT
    imageAcquired demyelinating syndromes include acute disseminated encephalomyelitis, transverse myelitis and may progress to multiple sclerosis (MS). Acute disseminated encephalomyelitis is characterized by impairment of level of consciousness and multifocal neurological deficits and transverse myelitis by back pain, weakness and sphincter dysfunction. Only a few cases of acquired demyelinating syndrome have been imaged with 18F-FDG PET/CT. We present two such cases.


  11. Ventriculopleural Shunt Dysfunction Due to a Loculated Pleural Collection Demonstrated on SPECT/CT Imaging
    imageA 35-year-old woman presented with increasing drowsiness on a background of childhood meningitis and hydrocephalus managed with a ventriculopleural shunt. Her cerebral CT and chest radiograph were unchanged from previous imaging and did not identify significant pathology. Because of clinical suspicion of cerebrospinal fluid shunt dysfunction, she was referred for a cerebrospinal fluid shunt study, which demonstrated tracer accumulation within a loculated pleural collection in the left costophrenic recess.



  12. Salivary Gland Activity Obscures Mandibular Metastasis of Prostate Carcinoma on 68Ga–Prostate-Specific Membrane Antigen PET
    imageWe report a case of a 65-year-old man with prostate cancer; his treatment history included radical prostatectomy followed by radiation therapy and subsequent androgen deprivation therapy for more than 5 years. He currently presented with a history of rising prostate-specific antigen and complained of jaw aches. 68Ga–prostate-specific membrane antigen PET/CT study performed for suspected biochemical recurrence demonstrated vertebral lesions and lesion in his jaw. Subsequent biopsy of jaw lesion demonstrated prostate cancer metastases.



  13. Dilated Internal Thoracic Vertebral Venous Plexus Simulating Bone Metastases on FDG PET/CT
    imageA 42-year-old woman with a newly diagnosed malignant thymoma underwent FDG PET/CT, which demonstrated an increased uptake in anterior mediastinal tumor and several pleural masses in the right hemithorax, compatible with “drop metastases.” In addition, contrast-enhanced CT images showed hyperdense abnormality in T2 vertebral body, congruent with intensely increased FDG uptake, raising suspicion of skeletal metastasis. This is a rare but important potential pitfall either in CT and FDG PET/CT—a “false-positive” bony lesion not attributed to skeletal metastasis but to dilated internal thoracic vertebral venous plexus associated with collateral circulation due to superior vena cava syndrome.



  14. Intense 68Ga-PSMA Uptake in Diverticulum of the Sigmoid Colon
    imageWe present a case of a diverticulum of the sigmoid colon with intense prostate-specific membrane antigen (PSMA) activity on 68Ga-PSMA PET/CT. CT scan and colonoscopy showed no signs of inflammation or malignancy. This case presents an addition to the collection of benign pitfalls when reporting PSMA PET/CT; however, a 68Ga-PSMA up-taking focus in the colon should always cause further examination, as malignant etiology must be ruled out.



  15. Serial FDG-PET/CT Imaging in the Management of Cardiac Sarcoidosis
    imageA 60-year-old woman with biopsy-proven cardiac sarcoidosis status post implantable cardioverter defibrillator placement presented with periodic dizziness and dyspnea on exertion. Myocardial perfusion scan demonstrated a moderate sized, fixed perfusion defect along the mid to proximal anteroseptal wall of the left ventricle, with better perfusion on stress images. FDG-PET/CT demonstrated corresponding focal FDG avidity of the mid to proximal anteroseptal wall, suggestive of active cardiac sarcoidosis. Because of severe side effects, mycophenolate mofetil was discontinued, and the patient received low-dose steroid therapy. At 7-month follow-up FDG PET/CT, there was increased FDG avidity in the same regions, indicating worsening cardiac sarcoidosis.


  16. The Role of FDG PET in Diabetic Myonecrosis: A Rare and Underrecognized Complication of Diabetes
    imageA 66-year-old man with poorly controlled type 2 diabetes was admitted for acute bilateral calf pain in the context of coronary artery disease, chronic renal failure, and peripheral neuropathy. Lower-extremity Doppler ultrasound excluded deep vein thrombosis. FDG-PET was performed to exclude a suspected infection because of elevated white blood cells and inflammatory markers but normal creatinine kinase levels. PET scan demonstrated intense bilateral calf muscle and left thigh muscle uptake, which in combination with the patient's history was consistent with diabetic myonecrosis, a rare end-stage complication of diabetes. The patient was managed conservatively, and pain resolved following a typical self-limited course.



  17. Prediction of Posthepatectomy Liver Failure Proposed by the International Study Group of Liver Surgery: Residual Liver Function Estimation With 99mTc-Galactosyl Human Serum Albumin Scintigraphy
    imagePurpose The International Study Group of Liver Surgery (ISGLS) proposed a definition and grading system for posthepatectomy liver failure (PHLF). We evaluated the usefulness of residual liver function estimation using 99mTc-galactosyl human serum albumin (99mTc-GSA) for the prediction of PHLF. Methods Patients with liver tumors (n = 136) and scheduled for hepatectomy underwent 99mTc-GSA scintigraphy. Based on their imaging data, the maximal GSA removal rate (GSA-Rmax)was calculated using multicompartment analysis. We also calculated GSA-Rmax in the predicted residual liver (GSA-RL) whose volume was determined on computed tomography (CT) scans. We compared the age, sex, 15-minute indocyanine green retention rate; albumin, bilirubin, hyaluronic acid, and type 4 collagen levels; the Child-Pugh classification; residual liver volume; residual liver percentage; GSA-Rmax; and GSA-RL in patients with and without PHLF. Univariate and multivariate logistic analyses were used for statistical assessments. Results Of 136 patients, 17 (12.5%) met the ISGLS criteria for PHLF (ISGLS-PHLF). There was a statistically significant difference in the age, albumin level, Child-Pugh classification, residual liver volume, residual liver percentage, GSA-Rmax, and GSA-RL between patients with and without PHLF. Based on multivariate analysis, GSA-RL and the residual liver volume were significant independent predictors of ISGLS-PHLF (P = 0.004 and P = 0.038, respectively). The odds ratio was 149423 for GSA-RL and 1.003 for the residual liver volume. Conclusions GSA-RL calculated using 99mTc-GSA scintigraphy was the most useful independent predictor for ISGLS-PHLF.



  18. Dynamic Adaptation of Tumor Immune Response With Nivolumab Demonstrated by 18F-FDG PET/CT
    imageA 61-year-old woman with lung adenocarcinoma failed first-line treatment and was placed on immunotherapy with nivolumab. FDG-PET/CT before immunotherapy showed metastases to thoracic nodes, liver, adrenal gland, and skeleton. Seven weeks after starting nivolumab, FDG-PET/CT showed mild residual activity in thoracic nodes and otherwise complete response. After 15 weeks, enlarged and FDG-avid axillary lymphadenopathy and worsening supraclavicular lymphadenopathy developed. After 20 weeks, FDG-PET/CT demonstrated marked improvement of axillary and supraclavicular lymphadenopathy. This case demonstrates that later progression of disease can still respond to continuing immunotherapy, hypothetically because of dynamic adaptations in the tug-of-war between the immunotherapy-augmented immune system and tumor.



  19. Incidental Detection of Medullary Thyroid Carcinoma by 68Ga-DOTATATE PET/CT in a Patient With Neuroendocrine Tumor Liver Metastases
    image68Ga-DOTATATE, a positron-emitting somatostatin analog, has been approved by the Food and Drug Administration for imaging neuroendocrine tumors (NETs). The presence of a second primary malignancy is common in NETs; however, synchronous primary malignancy in the thyroid has rarely been reported. The value of 68Ga-DOTATATE in medullary thyroid cancer is being investigated and is currently recommended for use when treatment with somatostatin analogs is an option. We present a 55-year-old man with abdominal pain associated with well-differentiated NET liver metastases and incidental medullary thyroid carcinoma demonstrated on a 68Ga-DOTATATE PET/CT.



  20. 68Ga-PSMA Avid Primary Adenocarcinoma of the Lung With Complementary Low 18F-FDG Uptake
    image68Ga-PSMA PET/CT scan on a 70-year-old man with recently diagnosed prostate cancer revealed a spiculating nodule in the apex of the left lung with intense 68Ga-PSMA uptake. The nodule had no pathological 18F-FDG uptake and turned out to be a primary adenocarcinoma of the lung. Cases with complementary pattern of uptake in 18F-FDG and 68Ga-PSMA in metastatic clear cell renal carcinoma and in well-differentiated hepatocellular carcinoma have previously been reported; however, this case illustrates that this unusual pattern can also be present in primary lung cancer.


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