Shambo Guha Roy

Use of 18F-FDG PET/CT imaging for evaluation of patients with primary splenic lymphoma.

Abstract Primary splenic lymphoma (PSL) is a rare disease, and its management differs from other splenic malignancies. The purpose of the present study was to evaluate the role of 18F-FDG PET/CT in patients with PSL. Methods We retrospectively evaluated the data of 17 patients with PSL (median age, 46 years; range, 3-64) who had undergone 50 18F-FDG PET/CT studies. Of the 50 PET/CTs, 15 were done for primary diagnosis/staging and 35 were done for restaging. PET/CT images were evaluated both qualitatively and quantitatively [maximum standardized uptake value (SUVmax)]. Combination of clinical/imaging follow-up and/or histopathologic diagnosis was taken as reference standard. Results Of the total 50 18F-FDG PET/CT studies, 27 studies (54%) were positive and 23 (46%) were negative for disease. PET/CT was true positive in 25 studies, true negative in 22 studies, false positive in 2 studies, and false negative in 1 study. Overall, per study-based sensitivity was 96.2%, specificity was 91.7%, and accuracy was 94%. In those studies performed for diagnosis/staging (15/50), PET/CT was true positive in all 15, with an accuracy of 100%. In those studies performed for restaging (35/50), sensitivity was 90.9%, specificity was 91.7%, and accuracy was 91.4%. No significant difference was seen in the accuracy of PET/CT between staging and restaging groups (P = 0.601). On 18F-FDG PET/CT, splenic involvement was seen in 24 studies, lymph nodal involvement in 5 studies, liver involvement in 3 studies, and bone marrow involvement in 1 study. More than one site of disease was seen in 9 PET/CT studies. On semiquantitative analysis, the overall mean splenic lesion SUVmax was 6.9 ± 7.9 (median, 4.6; range, 1.3–29). The mean value of ratio of SUVmax of splenic lesions and SUVliver was 4.4 ± 5.5 (median, 2.4; range, 0.9–24.2). On comparison of areas under the curve, the mean value of ratio of SUVmax of splenic lesions and SUVliver was found to be superior to SUVmax alone for this differentiation of involvement from normal spleen (P = 0.018). Conclusion 18F-FDG PET/CT seems useful in patients with primary splenic lymphoma and shows high diagnostic accuracy.

In Vivo Demonstration of PSMA Expression in Adenocarcinoma Urinary Bladder Using 68Ga-PSMA 11 PET/CT

In vitro and in vivo studies have demonstrated prostate-specific membrane antigen (PSMA) expression in various malignant and benign tumors. Based on the recent immunohistochemical study showing PSMA expression in adenocarcinoma of urinary bladder, we hypothesized that PSMA expression in adenocarcinoma of urinary bladder can be demonstrated in vivo using Ga-PSMA 11 PET/CT. We present a man with exstrophy bladder, presenting with adenocarcinoma urinary bladder referred for staging PET/CT. Both F-FDG and Ga-PSMA-11 PET/CT were done, which showed PSMA expression in the primary tumor as well as metastatic lymph nodes.

FDG-PET/CT in Skeletal Muscle: Pitfalls and Pathologies

FDG-PET/CT is an integral part of modern-day practice of medicine. By detecting increased cellular metabolism, FDG-PET/CT can help us detect infection, inflammatory disorders, or tumors, and also help us in prognostication of patients. However, one of the most important challenges is to correctly differentiate the abnormal uptake that is potentially pathologic from the physiological uptake. So while interpreting a PET/CT, one must be aware of normal biodistribution and different physiological variants of FDG uptake. Skeletal muscles constitute a large part of our body mass and one of the major users of glucose. Naturally, they are often the site of increased FDG uptake in a PET study. We as a nuclear medicine physician must be aware of all the pitfalls of increased skeletal muscle uptake to differentiate between physiological and pathologic causes. In this review, we have discussed the different causes and patterns of physiological FDG uptake in skeletal muscles. This knowledge of normal physiological variants of FDG uptake in the skeletal muscles is essential for differentiating pathologic uptake from the physiological ones. Also, we reviewed the role of FDG-PET/CT in various benign and malignant diseases involving skeletal muscle.

Diuretic 18F-Fluorodeoxyglucose PET/Computed Tomography in Evaluation of Genitourinary Malignancies

The interpretation of fluorodeoxyglucose (FDG) PET/computed tomography (CT) is often challenging for pelvic pathologies because of the physiologic bowel and urinary tract activity. Intense radiotracer activity in urinary tract interferes in image interpretation and leads to false-negative results in diagnosis and detection of local recurrence and regional lymph node metastases. It is imperative to minimize unnecessary urinary bladder activity to improve the diagnostic yield of PET/CT. All the techniques described in the literature have their pros and cons. This article discusses FDG PET/CT in evaluation of urinary bladder cancer, cervical cancer, and ovarian cancer.

Synchronous thoracic and abdominal enteric duplication cysts: Accurate detection with 99m Tc-pertechnetate scintigraphy

Enteric duplication cysts (EDCs) are uncommon congenital anomalies, which can occur anywhere along the gastrointestinal tract and vary greatly in presentation, size, location and symptoms. Ectopic gastric mucosa is reported to be found in 20-30% of these duplications. 99mTc-pertechnetate scintigraphy is a useful modality for preoperative localization of the ectopic functioning gastric mucosa in the EDCs. We report a case where 99mTc-pertechnetate scintigraphy was useful in detecting synchronous thoracic and abdominal duplication cysts with functioning gastric mucosa thus having an impact on the patient management.

Incremental value of single photon emission tomography/computed tomography in 3-phase bone scintigraphy of an accessory navicular bone

Accessory navicular bone is one of the supernumerary ossicles in the foot. Radiography is non diagnostic in symptomatic cases. Accessory navicular has been reported as a cause of foot pain and is usually associated with flat foot. Increased radio tracer uptake on bone scan is found to be more sensitive. We report a case highlighting the significance of single photon emission tomography/computed tomography in methylene diphosphonate bone scan in the evaluation of symptomatic accessory navicular bone where three phase bone scan is equivocal.

18F-FDG-PET/CT in staging, recurrence detection and response evaluation of primary splenic lymphoma with eight years follow up

Primary splenic lymphomas (PSL) are rare malignancies which involve spleen with or without splenic hilar lymph nodes. Confirmation of diagnosis depends upon tissue sampling but noninvasive methods are useful in early diagnosis, treatment response monitoring and recurrence detection. Here we describe a case of PSL detected by ¹⁸F-FDG-PET/CT which was histopathologically proven to be diffuse large B-cell lymphoma (DLBCL) treated with CHOP regimen. ¹⁸F-FDG-PET/CT was found to be very useful in all stages (staging, recurrence detection and treatment response monitoring) of PSL with eight years of follow up.

Importance of SPECT/CT in detecting multiple hemangiomas on 99mTc-labeled RBC blood pool scintigraphy.

Vascular malformations and hemangiomas are common in children, but gastric hemangioma is extremely rare with less than 15 reported cases in the pediatric age group. Gastric hemangioma accounts for only 0.05% of all gastrointestinal neoplasms, and intra-abdominal hemangiomas are rarely found outside of the liver. We present a unique case of gastric hemangioma, and multiple hemangiomas were detected in a single scan by 99mTc-labeled RBC blood pool imaging. This case also depicts the incremental role of SPECT/CT over planar acquisition for detecting multiple hemangiomas, especially for those lesions located adjacent to physiological blood pool activity.

Carcinoma of unknown primary of neuroendocrine origin: Accurate detection of primary with 68 Ga-labelled [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid]-1-NaI3-Octreotide positron emission tomography/computed tomography enterography

68Ga-labelled [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid]-1-NaI3-Octreotide (68Ga-DOTANOC) positron emission tomography/computed tomography (PET/CT) is an excellent modality in patients with carcinoma of unknown primary of neuroendocrine origin. Most of the primary lesions are located in mid gut region where the lesions have poor resolution due to undistended and overlapping intestinal loops and motility-related artifacts. Although PET/CT enteroclysis, enterography and colonography have been described with 18F-fluorodeoxyglucose, PET/CT enterography with68Ga-DOTANOC has not been described in the literature. Here, we present a case where68Ga-DOTANOC PET/CT enterography was useful in identifying the primary neuroendocrine tumor lesion in small intestine with accurate delineation.

Ictal PET in Ohtahara Syndrome With Hemimegalencephaly

Ohtahara syndrome is one of the causes of infantile epilepsies, which presents with refractory seizures and characteristic EEG changes. It is often associated with structural anomalies in the brain. We report a case of 5-month-old girl with Ohtahara syndrome with hemimegalencephaly who presented with refractory seizures and ictal FDG PET/CT helped in localizing the seizure focus.