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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.

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Background Transrectal US-guided biopsy with or without MRI fusion is performed for diagnosing prostate cancer (PCa) but has limitations. Gallium 68 (68Ga) prostate-specific membrane antigen (PSMA) PET/CT-guided targeted biopsy has the potential to improve diagnostic yield of PCa. Purpose To evaluate the safety and diagnostic yield of 68Ga PSMA PET/CT-guided, robotic-arm assisted transgluteal prostatic biopsy. Materials and Methods In this single-center nonrandomized prospective trial, participants with a clinical suspicion of PCa (serum prostate-specific antigen level > 4 ng/mL) were recruited from January 2019 to September 2020. After whole-body 68Ga PSMA PET/CT, participants with PSMA-avid intraprostatic lesions underwent PET-guided transgluteal biopsy by using an automated robotic arm. To assess safety and diagnostic yield, procedure-related complications and histopathologic results were documented. Pain during the procedure was scored by a visual analog scale. Descriptive statistics were applied; qualitative variables were reported in percentages. Results Seventy-eight participants (mean age, 66 years ± 7 [standard deviation]; 36 participants [46%] with prior negative results at transrectal US-guided biopsy) were enrolled. Fifty-six (72%) participants had PSMA-avid lesions (prior negative results at transrectal US-guided biopsy in 22 of 56 [39%]) and underwent targeted biopsy. PCa was confirmed in 54 of 56 (96%) participants, and clinically significant PCa (Gleason score ≥ 7) was confirmed in 24 of 54 (44%). Two participants had nonrepresentative samples that required rebiopsy. All participants experienced pain during the procedure, mild (median visual analog scale score, 1; interquartile range, 1-2) in 36 of 56 (64%) and moderate (median visual analog scale score, 5; interquartile range, 5-6) in 20 of 56 (36%). Postprocedure complications were noted in five of 56 (9%) participants and were minor (hematuria, four participants; hematospermia, one participant; and gluteal pain, two participants). No participant developed a postprocedural infection. Conclusion Transgluteal prostate-specific membrane antigen (PSMA) PET/CT-guided, robotic-targeted prostatic biopsy is safe with a high diagnostic yield of prostate cancer for PSMA-avid lesions. Clinical trial registration no. NCT05022576 © RSNA, 2022.

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AIMS: 99mTc-labeled RBC-equilibrium radionuclide angiocardiography (ERNA) is done in transfusion-dependent beta-thalassemia major (ß-TM) patients routinely for cardiac dysfunction. This prospective study aimed at evaluating the potential of ERNA in demonstrating the bone marrow hyperplasia as an adjunct biomarker for monitoring the adequacy of blood transfusions in transfusion-dependent ß-TM patients. MATERIALS AND METHODS: One hundred and twenty-six patients of ß-TM (study group) and 30 nonthalassemic patients (control) underwent ERNA study with an additional whole-body imaging. We quantitated the normalized bone marrow tracer uptake (due to marrow hyperplasia) and hepatic tracer uptake (indicator of hepatic perfusion) in both the groups on whole-body imaging. Liver and myocardial iron deposition were evaluated with T2* MRI in the thalassemic group. RESULTS: ß-TM group showed significantly increased mean normalized marrow count (MN) compared to the control group (P < 0.001) reflecting peripheral marrow hyperplasia (indirect marker for blood transfusion inadequacy). The hematological parameters in the study group showed a negative correlation with MN, without such correlation in the control group. The study group showed greater derangement in hepatic perfusion with significantly less mean normalized hepatic tracer uptake (HN) compared to the control group. Hepatic iron deposition (evaluated with T2* MRI) also showed a negative correlation with hepatic perfusion parameter (HN) assessed by ERNA, though myocardial iron deposition did not show any significant correlation with cardiac systolic/diastolic parameters evaluated by ERNA in the study group. CONCLUSION: ERNA study with these novel parameters (MN and HN) may have the potential to assess peripheral marrow hyperplasia and derangement in hepatic perfusion in transfusion-dependent ß-TM.

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Prostate cancer (PCa) is one of the major causes of death due to cancer in men. Conventional imaging modalities such as magnetic resonance imaging (MRI) provide locoregional status, but fall short in identifying distant metastasis. C-11 choline F-18 fluorocholine (F-18 FCH) has been shown to be useful in imaging of PCa. The present prospective study evaluates and compares the role of F-18 FCH positron emission tomography-computed tomography (PET-CT) with locoregional MRI and whole-body bone scintigraphy in PCa patients for initial staging and recurrence evaluation. This study included a total of 50 patients. Tc-99m skeletal scintigraphy, F-18 FCH PET-CT, and diffusion-weighted MRI of the pelvic region were performed within a span of 2-3 weeks of each other, in random order. For the primary site, core biopsy findings of the lesion were considered as gold standard. The kappa test was used to measure agreement between bone scintigraphy, F-18 FCH, and MRI. For comparing Tc-99m bone scintigraphy, F-18 FCH, and MRI, McNemar's test was applied. F-18 FCH PET-CT and MRI were able to detect primary lesion in all initial staging patients. The sensitivity and specificity of F-18 FCH PET-CT versus MRI were found to be 92.8% versus 89.2% and 100 versus 80%, respectively, for the recurrence at the primary site. A total of 55 bony lesions at distant sites were detected on F-18 FCH PET-CT in comparison to 43 bone lesions on whole-body bone scintigraphy. F-18 FCH PET/CT also detected additional lung lesions in 2 patients and abdominal lymph nodes in 12 patients. F-18 FCH PET-CT could detect primary lesions, local metastasis, bone metastasis, and distant metastasis in a single study and is also a useful modality in recurrence evaluation in PCa patients.

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Liver radiotracer activity interfering with the inferior myocardial wall in a patient undergoing myocardial perfusion imaging (MPI) with 99mTc-Sestamibi is a known pitfall. We report a patient with pituitary macroadenoma who was subjected to stress-MPI study for pre-anesthetic clearance. The post-stress raw image showed the liver radiotracer activity in close approximation to the anteroseptal wall of the left ventricular myocardium, secondary to right hemi-diaphragmatic eventration.

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PSMA-based radioligand therapies have shown the beneficial effect in metastatic castrate-resistant prostate cancer (mCRPC) patients when they become refectory to the established treatments with associated potential toxicities and high mortality rate. Ac-PSMA therapy is known to be remarkably effective in substantially pretreated mCRPC patients. However, posttherapy imaging is usually not performed as alpha emitters are really difficult to image. We presents a patient of mCRPC treated with Ac-PSMA-617, and his posttherapy whole-body scans acquired by using 3 different photopeaks (78, 218, and 440 keV) fairly demonstrated the tracer's distribution and the efficacy of targeted alpha therapy.

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99mTc-ethylenedicysteine (99mTc-EC) diuretic renal scintigraphy is an established, safe, and noninvasive study to evaluate relative renal function and drainage. We present a known case of bilateral renal stone disease who presented with acute urinary obstruction detected intraprocedurally on 99mTc-EC diuretic renography. He was managed subsequently with emergency double J stenting. The development of acute obstruction intraprocedurally in this patient may be resultant of forced diuresis caused by furosemide, dislodging the renal stones in the distal ureters. In the setting of renal calculi, cautious use of furosemide with watchful monitoring may be needed to see for the development of obstruction and manage accordingly.

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Ga-labeled prostate-specific membrane antigen (PSMA) ligand PET/CT is a rapidly evolving imaging modality for prostate cancer. However, with the widespread use of Ga-PSMA PET/CT, various reports of nonprostatic uptake of Ga-PSMA in both benign and malignant lesions have also appeared. We report a recently diagnosed case of prostate cancer demonstrating diffuse Ga-PSMA expression in both the lobes of thyroid gland, which on further clinical and biochemical investigations was established as hypothyroidism.

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Extraocular muscles show physiologic radiotracer uptake on F-FDG PET/CT as is encountered in most routine scans. Certain pathologies can cause palsy of one or more of the extraocular muscles, leading to hypometabolism on F-FDG PET/CT. We present a case with a classical finding of unilateral hypometabolism of the lateral rectus muscle, disrupting the "V" sign formed due to physiologic uptake. The patient had presented with the complaint of diplopia and was being evaluated further to rule out the possibility of inflammatory/granulomatous infectious etiopathogenesis leading to compression of the abducens nerve resulting in lateral rectus palsy.

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PURPOSE: Minimally invasive parathyroid carcinoma (MIPC) is clinically and biochemically comparable with parathyroid adenoma (PA) though histopathologically differ from PA. MIPC is an intermediate of PA and parathyroid carcinoma (PC). In literature, there is no definite criterion to diagnose MIPC. Our aim was to evaluate and characterize the imaging and biochemical parameters with histological characteristics of MIPC. METHODOLOGY: Ten patients with MIPC were recruited from (single centre) Indian PHPT registry (www.indianphptregistry.com) from January 2014 to July 2018. Clinical, biochemical, imaging and histological features of MIPC patients were reviewed. RESULTS: The mean age of MIPC patients (n = 10; 3 males) was 39.9 ± 11.3 years (range: 17-50). All patients had an elevated preoperative parathyroid hormone (iPTH) level ranging from 427 to 2138 pg/mL (median: 1328). MIBI scan showed intensely avid and enlarged parathyroid tumours in all patients; LIPT in 6, RIPT in 3 and ectopic mediastinal in 1 with mean size of the tumours was 2.8 ± 1.1 cm. The mean of maximum standardized uptake value (SUVmax) of MIPC in F-18 fluorocholine PET/CT was 6.7 ± 1.1 (range 6.0-8.3). The mean tumour weight was 12 ± 9.5 g (range: 1.09-28). All MIPC patients had identified capsular invasion in 80% and vascular invasion in 50% only but there was no local invasion, lymph nodal or distant metastasis. The mean Ki-67 labelling index was 3.2 ± 2.7 (range 1.1-10). CONCLUSION: The study concluded that MIPC patients are less aggressive (on the basis of imaging and histopathological findings) and should be differentiated from parathyroid adenoma and carcinoma.

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Although 18F-fluorodeoxyglucose (FDG) is the most extensively used tracer in oncological positron emission tomography/computed tomography (PET/CT) studies, various physiological as well as benign pathological conditions are known to cause false-positive results. This report describes 18F-FDG PET/CT done in an elderly man with primary hepatocellular carcinoma, revealing a metastasis mimicking lesion in the left inguinal canal, which was identified as the herniated portion of the urinary bladder. Though rare, bladder herniation, especially with a narrow neck, can be a pitfall in the evaluation for metastatic disease. The study also highlights the utility of delayed imaging in the evaluation of pelvic pathology.

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Skeletal muscle uptake of F-FDG can result from a variety of physiologic and pathologic conditions. It is important for the physician to interpret these uptake patterns in the correct context to avoid a misdiagnosis. We present a case of a 36-year-old man with progressive, repeated episodes of regurgitation who was diagnosed with adenocarcinoma of the stomach. F-FDG PET/CT showed increased tracer uptake in the primary tumor and in the intercostal and sternocleidomastoid muscles. The pattern of tracer uptake along with the clinical history and examination of the patient helped differentiate a physiologic variant from a pathologic cause.

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We present a case of endometrioid carcinoma metastasis in the bladder mimicking as the second primary of urinary bladder on 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT). The presentations of bladder lesions on 18F-FDG PET/CT are varied, and rare presentations of common malignancies can pose a significant diagnostic challenge as in the index case and highlight the importance of histopathological examination to confirm any unusual FDG uptake confounding the diagnosis.

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Hepatic epithelioid hemangioendothelioma (EHE) is an uncommon vascular tumor, primarily seen in 20-40 years of age. We report the case of a 14-year-old boy with EHE and distant metastases identified on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), leading to a change in the management plan. 18F-FDG PET/CT proved to be useful in identifying the rare sites of metastasis and planning further treatment.

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We present a case of biopsy-proven prostatic adenocarcinoma with a tracer-avid left paravertebral location at D4 to D5 vertebrae, suggestive of metastasis. However, in view of uncommon location of single-site metastasis at paravertebral region with no tracer-avid regional lymphadenopathy, image-guided biopsy was done, which was suggestive of paraganglioma. Ga-PSMA is known to have variable tracer avidity in multiple nonprostatic benign as well as malignant lesions, and our case adds to the list of nonspecific uptake by this once considered "specific" to prostate PET radiotracer.

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Ga-DOTANOC PET/CT is well documented in evaluation of well-differentiated neuroendocrine tumors and in other lesions with somatostatin receptor expression such as pheochromocytoma, paraganglioma, neuroblastoma, meningioma, and mesenchymal tumors causing oncogenic osteomalacia. Causes of interpretative pitfalls include prominent pancreatic uncinate process activity, inflammation, osteoblastic activity (degenerative bone disease/fracture/vertebral hemangioma), splenunculi/splenosis, and others. We present a case of extraskeletal paravertebral lesion detected in a known case of breast cancer with increased Ga-DOTANOC uptake later proved to be hemangioma. This is a novel finding and should be kept as a rare benign differential in evaluation of lesions with somatostatin receptor expression.

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Adenoid cystic carcinoma of the buccal mucosa has an increased propensity for recurrence and distant metastases. Due to the poor prognosis at late detection of distant metastases, it is advisable to keep a close follow-up. In the present case, 18F-fluorodeoxyglucose positron emission tomography/computed tomography proved invaluable in the comprehensive workup of the patient, including detection of local recurrence, distant metastases, and in assessing treatment response.

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We present a case of a 22-year-old man with history of allogenic renal transplantation on immunosuppression, who underwent F-FDG-PET/CT to characterize a lesion in the transplanted kidney on ultrasonogram and contrast-enhanced computed tomography imaging. PET/CT revealed FDG avid lesion in the transplanted kidney and mural thickening involving the distal ileum, ileocecal junction, and ileocolic lymph nodes. Subsequent histopathological examination from the renal lesion revealed renal cell carcinoma in the transplanted kidney. Additionally, endoscopic biopsy from the ileal thickening revealed granulomatous inflammation, suggesting tuberculosis, which was missed on both ultrasonogram and contrast-enhanced CT imaging.

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