18F-FDG PET/CT Imaging in Adrenal Cryptococcosis.

Cryptococcosis is a fungal infection, relatively rare in the absence of impaired immunity. Lung or brain may be involved. Cryptococcal dissemination is rare in absence of impaired immunity, and documentation of alone adrenal involvement without central nervous system involvement is rare. Here, we present a case of an immunocompetent patient presented with bilateral adrenal cryptococcosis with adrenal insufficiency, without central nervous system involvement and F-FDG PET/CT correctly identified the residual disease.

Occult breast primary malignancy presenting as isolated axillary lymph node metastasis - early detection of primary site by 18F-FDG PET/CT.

Breast cancer patients rarely present with isolated axillary lymph node metastasis without any clinical or radiological evidence of primary tumor. Identification of the primary site of tumor helps in planning appropriate patient management which has definite impact on patient's survival. We present here a case of 30-year-old female who presented with isolated right axillary lymph node metastasis with no evidence of primary tumor clinically. Conventional imaging modalities were negative for primary site. She underwent whole body 18F-Flurodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and it contributed significantly in early detection of occult primary tumor in right breast.

Somatostatin receptor based PET/CT imaging with 68Ga-DOTA-Nal3-octreotide for localization of clinically and biochemically suspected insulinoma.

BACKGROUND: Localization of primary tumor in insulinoma is often difficult. We evaluated the role of 68Ga-DOTA-Nal3-Octreotide (DOTANOC) PET/CT for localization of primary tumor in patients with clinical and biochemical suspicion of insulinoma. METHODS: Data of 35 patients (age: 38.4±16.5 years) who underwent 68Ga-DOTANOC PET/CT for clinical and biochemical suspicion of insulinoma (hypoglycemia, raised serum insulin and C-peptide levels) were retrospectively analyzed. PET/CT images were evaluated visually and semiquantitatively (SUV) by two experienced nuclear medicine physicians. A definite lesion in pancreas on non contrast CT showing increased 68Ga-DOTANOC was taken as positive. In the absence of CT lesion focal 68Ga-DOTANOC uptake in the pancreas more than liver was taken as positive. All patients had also undergone conventional imaging (CIM) (CT/MRI/endosonography) and their reports were retrieved for comparison. Histopathology and/or imaging/clinical/biochemical follow up (minimum 6 months) was used as reference standard. RESULTS: The mean serum insulin levels was 51.6±54 µIU/mL and C-peptide level was 6.9±7.3 ng/mL. 68Ga-DOTANOC PET/CT was interpreted as positive in 11 patients (31.5%) and negative in 24 (68.5%). PET/CT demonstrated total 16 pancreatic lesions in 11 patients. In two patients it also showed both liver and lymph nodal metastases. 68Ga-DOTANOC PET/CT was true positive in 8, true negative in 1, false positive in 3 and false negative in 23 patients. Per patient based sensitivity of PET/CT was 25.8% (95% CI: 11.8-44.6), specificity was 25% (95% CI: 0.6-80.5) and accuracy was 25.7%. The mean SUVmax of pancreatic lesions was 13.8±11.1. On comparison no significant difference was seen between CIM and PET/CT on patient based (P=1.00) or lesion based comparison (P=0.790). CONCLUSION: 68Ga-DOTANOC PET/CT has limited utility for localizing the primary tumor in patients with clinical and biochemical suspicion of insulinoma. However, it might be useful for differentiating benign and malignant insulinoma. Further prospective comparative studies are warranted.

Dystrophic calcification in muscles of legs in calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia syndrome: Accurate evaluation of the extent with (99m)Tc-methylene diphosphonate single photon emission computed tomography/computed tomography.

We present the case of a 35-year-old man with calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia variant scleroderma who presented with dysphagia, Raynaud's phenomenon and calf pain. (99m)Tc-methylene diphosphonate bone scintigraphy was performed to identify the extent of the calcification. It revealed extensive dystrophic calcification in the left thigh and bilateral legs which was involving the muscles and was well-delineated on single photon emission computed tomography/computed tomography. Calcinosis in scleroderma usually involves the skin but can be found in deeper periarticular tissues. Myopathy is associated with a poor prognosis.

Accurate Characterization of Skeletal Lesions in Tuberous Sclerosis Complex Using 99mTc MDP SPECT/CT.

We report a 15-year-old patient with tuberous sclerosis complex or Bourneville's disease with history of generalized tonic-clonic seizure for last 2 years and was currently on antiepileptic medication. He also had a history of left nephrectomy for renal cell carcinoma clear cell type. The patient had multiple adenoma sebaceum over the nasolabial region, ash leaf spots over the lower limbs, a Shagreen patch over the back, and multiple calcified tubers in the subependymal region. He was then referred for the skeletal scintigraphy to look for skeletal lesions, which revealed involvement of bilateral humeri, tibiae, and iliac bones accurately characterized on SPECT/CT.

Spectrum of Physiologic and Pathologic Skeletal Muscle (18)F-FDG Uptake on PET/CT.

OBJECTIVE: Skeletal muscle (18)F-FDG uptake on PET/CT can be either physiologic or related to a variety of different pathologic conditions. FDG PET/CT can be used for assessment of primary and metastatic tumors and infective or inflammatory conditions affecting the musculature. CONCLUSION: In this article, we describe the various causes and patterns of skeletal muscle FDG uptake. Familiarity with these patterns is essential for proper interpretation of clinical FDG PET/CT images.

Characterization of parallel-hole collimator using Monte Carlo Simulation.

OBJECTIVE: Accuracy of in vivo activity quantification improves after the correction of penetrated and scattered photons. However, accurate assessment is not possible with physical experiment. We have used Monte Carlo Simulation to accurately assess the contribution of penetrated and scattered photons in the photopeak window. MATERIALS AND METHODS: Simulations were performed with Simulation of Imaging Nuclear Detectors Monte Carlo Code. The simulations were set up in such a way that it provides geometric, penetration, and scatter components after each simulation and writes binary images to a data file. These components were analyzed graphically using Microsoft Excel (Microsoft Corporation, USA). Each binary image was imported in software (ImageJ) and logarithmic transformation was applied for visual assessment of image quality, plotting profile across the center of the images and calculating full width at half maximum (FWHM) in horizontal and vertical directions. RESULTS: The geometric, penetration, and scatter at 140 keV for low-energy general-purpose were 93.20%, 4.13%, 2.67% respectively. Similarly, geometric, penetration, and scatter at 140 keV for low-energy high-resolution (LEHR), medium-energy general-purpose (MEGP), and high-energy general-purpose (HEGP) collimator were (94.06%, 3.39%, 2.55%), (96.42%, 1.52%, 2.06%), and (96.70%, 1.45%, 1.85%), respectively. For MEGP collimator at 245 keV photon and for HEGP collimator at 364 keV were 89.10%, 7.08%, 3.82% and 67.78%, 18.63%, 13.59%, respectively. CONCLUSION: Low-energy general-purpose and LEHR collimator is best to image 140 keV photon. HEGP can be used for 245 keV and 364 keV; however, correction for penetration and scatter must be applied if one is interested to quantify the in vivo activity of energy 364 keV. Due to heavy penetration and scattering, 511 keV photons should not be imaged with HEGP collimator.

Metastatic Neuroendocrine Tumour in a Renal Transplant Recipient: Dual-Tracer PET-CT with (18)F-FDG and (68)Ga-DOTANOC in This Rare Setting.

Recipients of renal transplant are at increased risk of developing various malignancies, especially post-transplant lymphoproliferative disorder (PTLD) and skin cancers. Neuroendocrine tumours (NET) of the gastrointestinal tract have not been reported in this setting. Here we describe the case of a 75-year-old male who had undergone renal transplant 8 years back and now presented with significant weight loss and backache, clinically suspected as PTLD. (18)F-Fluordeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) showed hypermetabolic lesions in the liver and rectum, raising the suspicion of PTLD. However, biopsy from the liver lesion showed poorly differentiated NET. (68)Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI(3)-octreotide ((68)Ga-DOTANOC) PET-CT was then done, which confirmed the primary lesion in the rectum with liver metastases.

Accuracy of 68Ga DOTANOC PET/CT Imaging in Patients With Multiple Endocrine Neoplasia Syndromes.

OBJECTIVE: The aim of this study was to evaluate the role of 68Ga DOTANOC PET/CT imaging in patients with multiple endocrine neoplasia (MEN) syndromes. PATIENTS AND METHODS: Data of 33 patients (age, 33.5 [13.8] years; male 14/female 19) with MEN syndromes (MEN 1, 9; MEN 2A, 19; MEN 2B, 5) who underwent 41 68Ga DOTANOC PET/CT studies were retrospectively analyzed. Twenty PET/CTs were done for staging and 21 for restating. PET/CT images were evaluated in consensus by 2 nuclear medicine physicians, qualitatively and semiquantitatively (SUV(max)). A combination of histopathology, clinical, and biomarker follow-up was taken as reference standard. RESULTS: Of the total 41 68Ga DOTANOC PET/CTs, 34 were interpreted as positive for neuroendocrine tumors (NETs) and 7 as negative. The patientwise sensitivity of PET/CT was 94% (95% confidence interval [CI], 80-99), specificity was 71% (95% CI, 29-96), positive predictive value was 94% (95% CI, 80-99), negative predictive value was 71% (95% CI, 29-96), and accuracy was 90%. A total of 74 disease sites were demonstrated on PET/CT, including 41 primary NETs (pancreas, 10; stomach, 2; pheochromocytoma, 10; medullary thyroid carcinoma, 19), 31 metastatic sites (lymph node, 15; liver, 10; bone, 4; lung, 1; breast, 1), and 2 parathyroid adenomas. Lesionwise sensitivity, positive predictive value, and accuracy of PET/CT were 93%, 96%, and 90% overall, 89%, 95%, and 85% for primary tumors, and 100%, 97%, and 97% for metastasis, respectively. Among primary tumors, the SUV(max) of medullary thyroid carcinoma was significantly lower than gastro pancreatic NETs (P = 0.003) and pheochromocytomas (P = 0.003). No site-specific difference was seen in SUV(max) of metastatic lesions. CONCLUSIONS: 68Ga DOTANOC PET/CT shows high diagnostic accuracy in MEN syndrome and can demonstrate both primary and metastatic NETs in these patients.

Gastrointestinal stromal tumour with unusual sites of metastasis: accurate staging with 18F-FDG PET/CT / Tumor del estroma gastrointestinal con metástasis en localización poco habitual: una estadificación correcta con 18F-FDG PET/TC

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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. (99m)Tc-pertechnetate scintigraphy is a useful modality for preoperative localization of the ectopic functioning gastric mucosa in the EDCs. We report a case where (99m)Tc-pertechnetate scintigraphy was useful in detecting synchronous thoracic and abdominal duplication cysts with functioning gastric mucosa thus having an impact on the patient management.

Potential role of (18)F-2-fluoro-2-deoxy-glucose positron emission tomography/computed tomography imaging in patients presenting with generalized lymphadenopathy.

Generalized lymphadenopathy is a common and often vexing clinical problem caused by various inflammatory, infective and malignant diseases. We aimed to review briefly and highlight the potential role of (18)F-2-fluoro-2-deoxy-glucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) in such patients. (18)F-FDG PET/CT can play an important role in the management of generalized lymphadenopathy. It can help in making an etiological diagnosis; can detect extranodal sites of involvement and employed for monitoring response to therapy.

An uncommon case showing three different pathologies on (99m)technetium-methylene diphosphonate bone scintigraphy.

(99m)Technetium-methylene diphosphonate bone scintigraphy (BS) has an important role in evaluating skeletal pathology, especially its extent. Incidental extra-osseous uptake may sometimes be seen in soft-tissue pathologies. We present a 64-year-old female with skull base osteomyelitis referred for BS which revealed involvement of the skull base on the left side, uptake was also noted in bilateral lungs secondary to hypercalcemia of renal failure and in the D12-L1 vertebrae as the patient had a history of Pott's spine. This is perhaps a unique case showing three findings each of a different etiology in the same scan.

The role of 18F fluorodeoxyglucose positron emission tomography (18F-FDG-PET) in children with rheumatic carditis and chronic rheumatic heart disease.

BACKGROUND: We report the use of positron emission tomography (PET) using 18F-FDG for the diagnosis of carditis in children with rheumatic heart disease (RHD). MATERIAL AND METHODS: Thirty-six children aged 6-17 years (seventeen males and nineteen females) with isolated rheumatic significant mitral regurgitation (MR) underwent FDG-PET scanning of the heart after fasting for 6 h within a period of 2 years. They were divided into two groups based on Jones criteria - acute rheumatic carditis and chronic RHD. Age- and gender-matched twelve children who underwent whole body ¹8F-FDG-PET scan for routine PET scan for oncological evaluation was taken as controls. Nineteen patients had active carditis and 17 were chronic RHD cases. RESULTS: All 12 controls and all 17 cases with chronic RHD with MR showed diffuse uptake pattern. Of the 19 active cases, 14 showed ¹8F-FDG uptake in the myocardium, 5 did not show any uptake. Thus the finding of no uptake pattern on ¹8F-FDG-PET scan had a sensitivity of 26% but positive predictive value of 100% for acute carditis cases. This study describes the ¹8F-FDG-PET uptake pattern in children with RHD and in 12 age-matched control subjects in the fasting state. Those with chronic RHD with MR showed diffuse myocardial uptake pattern similar to that of the control group. Patients with active carditis showed mixed results; the majority showed diffuse uptake pattern. CONCLUSION: In view of its poor sensitivity, ¹8F-FDG-PET is not recommended as a routine imaging modality for the diagnosis of rheumatic carditis.

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.

99mTc-MDP SPECT/CT demonstrating extraosseous periarticular amyloid deposits in primary systemic amyloidosis associated with multiple myeloma.

Amyloidosis is a rare disorder characterized by variable extracellular accumulation of a complex substance consisting of proteinaceous fibrils (amyloid fibrils) and nonfibrillar glycoprotein or amyloid P component. We present a case of a primary systemic amyloidosis associated with multiple myeloma in a 48-year-old woman whose Tc-MDP SPECT/CT study revealed extraosseous periarticular uptake in amyloid deposits with no abnormal focal tracer uptake in the bone.

Staging and response of sternal histoplasmosis by 18F-FDG PET/CT.

Histoplasmosis, a granulomatous mycosis caused by the fungus Histoplasma capsulatum, is known to primarily affect the lungs and the immune system, with involvement of skeletal system as a rare manifestation, in which case the disease usually assumes multifocality. We present a singular case of a young man diagnosed to have an isolated skeletal histoplasmosis involving the body of sternum where 18F-FDG PET/CT played major role in both diagnosis and in response evaluation to antifungal therapy.