Metabolic signatures of malignant and non-malignant mass-forming lesions in the periampulla and pancreas in FDG PET/CT scan: an atlas with pathologic correlation.

Positron emission tomography (PET) has been used for the characterization of pancreatic and periampullary lesions. Pancreatitis-associated inflammation affecting only a portion of the pancreas gives the appearance of a mass lesion on imaging. Consequently, the differential diagnosis between cancer and pancreatitis becomes a commonly encountered problem. Traditionally, PET was interpreted as positive (to denote malignancy) if fluorodeoxyglucose (FDG) activity in the pancreas exceeded background activity and as negative (to denote benign) if activity was less than or equal to background activity. However, the specificity was limited with this method of interpretation. A relatively wide overlap has been reported between semiquantitative uptake values obtained in cancers and those in inflammatory lesions. Also, the qualitative (metabolic patterns) and quantitative variables (standardized uptake values) have been complementary and at sometimes controversial to each other in various clinical situations. There is paucity of data in the literature highlighting the role of FDG PET/CT in characterization of such mass lesions. The primary aim of this pictorial review is to list the various pathologic processes of pancreas and periampulla that could be studied with FDG PET/CT and recognize the different FDG uptake patterns and apply this information to characterize the different lesions affecting the pancreas and periampulla. We have also discussed the limitations of conventional imaging and advantages of FDG PET/CT for the evaluation mass-forming lesions of the pancreas and periampulla.

Diagnostic accuracy of F-18 FDG PET/CECT vs. CECT for detecting recurrence of periampullary carcinoma and its prognostic significance.

PURPOSE: To evaluate the additive value of whole-body F-18 fluoro-deoxyglucose positron emission tomography (FDG PET) as an adjunct to contrast-enhanced computed tomography (CECT) for detecting recurrence following Whipple's resection for periampullary carcinoma and to analyze the prognostic significance of FDG PET-/CECT-based detection of recurrence. METHODS: Fifty patients (34 males, 16 females; mean age: 55 ± 11 years) who underwent PET/CECT following resection of periampullary carcinoma were included. The study was duly approved by the institutional ethical committee for retrospective analysis of the data. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of FDG PET/CECT and CECT alone for detection of recurrence were calculated, and the accuracy was compared with ROC analysis. The prognostic factors for survival following recurrence were analyzed by univariate and multivariate methods. RESULTS: PET/CECT indicated recurrence of disease in 26 (52%) patients. The overall mean survival time was 46 months with an overall survival rate of 42%. The sensitivity, specificity, PPV, NPV and accuracy of PET/CECT and CECT for detection of recurrence were 96.1%, 91.6%, 92.6%, 95.6%, 94% and 76.9%, 75%, 76.9%, 75%, 76%, respectively (p = 0.037). Also change in management could have been achieved in 18% of patients based on the PET/CECT results. In univariate analyses, SUVmax >7.3 was the only predictor of poor survival (p < 0.05). CONCLUSION: PET/CECT could be used as a one-stop imaging tool for staging and prognostication of recurrent periampullary carcinoma that could result in better patient management.

F-18 FDG PET/CT in the evaluation of Takayasu arteritis: an experience from the tropics.

OBJECTIVE: To evaluate the performance parameters of FDG PET/CT in patients with Takayasu arteritis at diagnosis and during immunosuppression. METHODS: Retrospective analysis of 60 FDG PET/CT studies in 51 patients was performed (17 scans at diagnosis out of which 4 had follow-up scans also and 43 scans on immunosuppression). The degree of FDG uptake in the vessels was assessed visually using a 4-point scale and maximum standardized uptake value (SUVmax), SUVratio, extent of vasculitis and association with ESR were calculated. RESULTS: PET/CT was positive for active vasculitis in all 17 patients at diagnosis. The mean SUVmax and mean SUV ratio of the active areas were 5.1 ± 3.0 and 3.2 ± 1.9, respectively. On immunosuppression, PET scan was positive for active vasculitis in 14/43 (32.5%) scans. The mean SUVmax and mean SUVratio of the active areas were 1.7 ± 2.1 and 0.95 ± 1.2, respectively. There was significant difference between the mean SUVmax and mean SUVratio at diagnosis and on immunosuppression, respectively (P < .01). The median number of vascular segments in each uptake grade group was also statistically different (P < .01) between scans at diagnosis and on immunosuppression. The median ESR level in PET positive scans was 29 mm/hour (2-53), whereas in PET negative scans was 35.5 mm/hour (6-50) and the difference was not statistically significant. CONCLUSION: FDG PET/CT showed good sensitivity to detect active vasculitis at diagnosis and during immunosuppression. The change in SUVmax between the successive FDG PET/CT scans may give an objective assessment of response to immunosuppression.

Role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in the characterization of pancreatic masses: experience from tropics.

BACKGROUND AND AIM: Early detection and differentiation of malignant from benign pancreatic tumors is very essential as mass-forming pancreatitis is a frequently encountered problem. Positron emission tomography (PET) has a role in establishing the diagnosis of pancreatic carcinoma when the conventional imaging modalities or biopsies are nondiagnostic. In this prospective study, the utility of fluorodeoxyglucose (FDG)-PET/computed tomography (CT) in the characterization of mass-forming lesions of the pancreas was reported. METHODS: (18)F-FDG-PET/CT was prospectively performed in 87 patients diagnosed to have periampullary or pancreatic mass. Lesions with focally increased FDG uptake in PET/CT were considered malignant, whereas those with diffuse or no FDG uptake were considered benign. Semiquantitative analysis with maximum standardized uptake value (SUVmax) was also calculated. The PET/CT results were compared with histopathological results in all patients. RESULTS: Based on the FDG uptake pattern, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for FDG-PET/CT in characterizing the periampullary and pancreatic masses into benign and malignant lesions were 93%, 90%, 95%, 87%, and 92% respectively. Receiver operating characteristics curve analysis of the SUVmax of the lesions yielded a cut-off value of 2.8, with a sensitivity and specificity of 87.5% and 45% respectively. CONCLUSION: The FDG uptake pattern in PET/CT can differentiate malignant from benign mass-forming lesions of the pancreas with high accuracy and a discrete cut-off value of SUVmax could not be defined for the same as even lesions with pancreatic tuberculosis showed very high FDG uptake. Hence, in patients with a suspicion of malignancy in the pancreas, a focally increase FDG uptake in PET/CT suggests the diagnosis of malignancy.

Ventricular ejection fraction in patients with dilated cardiomyopathy calculated by gated blood pool SPET processing software: correlation with multigated acquisition and first pass radionuclide ventriculography.

This study was performed to find out the left ventricular ejection fraction (LVEF) and right ventricular ejection fraction (RVEF) in patients with dilated cardiomyopathy (DCM) by using commercially available automated gated blood pool scintigraphy (GBPS) processing software and to correlate it with first pass radionuclide ventriculography (FPRNV) and planar multigated acquisition (MUGA). However, till date, no literature exists studying the application of GBPS and planar radionuclide ventriculography techniques in the setting of patients with DCM as a single cohort. Forty-one patients having DCM were prospectively included in the study. First pass RNV and MUGA were performed at rest after in-vivo labeling of red blood cells in all patients. Immediately after obtaining the planar views, GBPS was performed and LVEF and RVEF were calculated. Our results showed that the %LVEF values (mean±SD) calculated by MUGA, GBPS and echo cardiography were 31±11, 34±12 and 32±11, respectively. The % RVEF values (mean±SD) calculated by FPRNV and GBPS were 46±14 and 43±17, respectively. The LVEF values calculated by MUGA, GBPS and echcardiography showed very good correlation r=0.924 and r=0.844, respectively and for both P <0.0001. Bland-Altman plot showed overestimation for LVEF (and a tendency for overestimation of RVEF) values calculated by GBPS compared to MUGA. Values of RVEF calculated by GBPS and FPRNV also showed good correlation (r=0.88; P< 0.0001). In conclusion, the automated GBPS for LVEF and RVEF calculation using GBPS SPET can be routinely applied in DCM patients. Given the practical difficulties with FPRNV like good bolus administration, quantitative blood pool SPET (QBPS) can be used to calculate RVEF. Similarly MUGA and GBPS can be used to calculate LVEF.

(18)F-FDG PET/CT in bilateral primary adrenal T-cell lymphoma.

Primary adrenal lymphoma is extremely rare. We report a young patient who presented with non- specific symptoms of fever and abdominal pain. Conventional imaging modalities demonstrated bilateral bulky adrenal masses, and whole-body fluorine-18-fluorodesoxyglucose ((18)F-FDG) positron emission tomography/computed tomography showed intense (18)F-FDG-avid bilateral adrenal masses with no evidence of extra-adrenal spread. A pathological diagnosis of non-Hodgkin lymphoma of peripheral T-cell type was made. The present case indicates that primary adrenal lymphoma should be included in the differential diagnosis of bilateral adrenal masses.

Advantage of Hybrid 18F-Fluoride Positron Emission Tomography/Computed Tomography to Diagnose Malignant Rib Invasion by Pleural Metastasis in a Background of Reactive Periostitis.

Diffuse osteoblastic activity in the ribs on bone scan is seen in association with pleural thickening. Irrespective of the pleural pathology, this represents benign finding caused by pleural hyperemia or reactive periostitis, with preserved cortical integrity. However, malignant involvement of the ribs can occur by local invasion of pleural malignancy causing cortical lysis. Herein, we describe the 18F-fluoride positron emission tomography/computed tomography findings of reactive periostitis of the ribs in pleural metastasis and emphasize the advantage of hybrid imaging in detecting local malignant tumor invasion superimposed in such condition.

Delayed 68Ga-PSMA PET/CT Image-Guided Biopsy for Low-Grade Adenocarcinoma in Benign Prostatic Hyperplasia.

ABSTRACT: Image-guided biopsy of prostate with multiparametric MRI is being adopted in the workup of prostate adenocarcinoma (PAC). 68Ga-PSMA PET/CT-guided biopsy has also been shown to be equally sensitive in the evaluation of higher-grade tumors with increased PSMA expression. The sensitivity of 68Ga-PSMA PET/CT, however, reduces with lesser PSMA expression in low-grade PAC. Herein, we demonstrate a case where delayed 68Ga-PSMA PET/CT imaging helped in detecting low-grade PAC in BPH.

Obstructive Jaundice: An Unusual Presentation of Neuroendocrine Differentiation in Prostatic Adenocarcinoma.

An elderly male on androgen deprivation therapy for prostatic adenocarcinoma presented with obstructive jaundice. Since biopsy from the head of the pancreas showed neuroendocrine carcinoma (NEC), he was diagnosed with second primary pancreatic NEC. Ga-68 DOTANOC positron emission tomography/computed tomography (PET/CT) done subsequently showed enlarged mildly DOTANOC-avid retroperitoneal nodes infiltrating the pancreas. These nodes were found to be progression of prostate-specific membrane antigen (PSMA) nonavid retroperitoneal nodes visualized in his Ga-68 PSMA PET/CT performed at another institution before 4 months, when there was no lesion in the pancreas. This observation revised the diagnosis from second primary pancreatic NEC to progression of neuroendocrine differentiation in preexisting prostatic adenocarcinoma.

De Novo Presentation of Sarcoidosis on Restaging FDG PET/CT in Rectal Carcinoma With Self-resolution.

Sarcoidosis is a systemic disorder of unknown etiology characterized by development of noncaseating granulomas in more than 1 organ system. Development of sarcoidosis during or immediately after chemotherapy and immunotherapy is not uncommon. We present a 61-year-old woman in whom restaging F-FDG PET/CT detected asymptomatic sarcoidosis after neoadjuvant chemoradiotherapy for carcinoma rectum, which resolved spontaneously by the end of adjuvant chemotherapy with no specific treatment. Recognition of anatomic-metabolic pattern of sarcoidosis could prevent erroneous upstaging of the primary malignancy during restaging PET/CT following chemotherapy, and such lesions may show self-resolution.

Fluorodeoxyglucose-positron emission tomography/computed tomography performs better than contrast-enhanced computed tomography for metastasis evaluation in the initial staging of pancreatic adenocarcinoma.

OBJECTIVE: To evaluate the additional role of FDG-PET/CT to the conventional multiphasic CECT in the initial staging of pancreatic adenocarcinoma. METHODS: 54 patients diagnosed with pathologically proven pancreatic malignancy underwent FDG-PET/CECT. The sensitivity, specificity, PPV, NPV, and accuracy of PET/CT and CECT for nodal and metastatic staging were calculated. The statistical difference was calculated by McNemar's test. RESULTS: Of 54 patients, 15 had distal metastasis. The sensitivity, specificity, PPV, NPV, and accuracy of PET/CT and CECT for nodal staging were 33 vs 89%, 84 vs 100%, 67 vs 100%, 60 vs 90%, and 59 vs 95%, respectively, p < 0.001. The sensitivity, specificity, PPV, NPV, and accuracy of CECT for metastatic staging were 73, 87, 69, 89, and 83%, whereas the accuracy of PET/CT was 100%, p = 0.01. By correctly characterizing unsuspected distant lesions, PET/CT could change management in 19% of patients. CONCLUSION: FDG-PET/CT can contribute to change in the management in almost one of every five patients of PA evaluated with the standard investigations during the initial staging.

A rare case of asymptomatic radioiodine-avid renal and brain metastases 20 years after hemi-thyroidectomy for adenomatous goiter.

A 65-year-old patient, with a history of left hemi-thyroidectomy for adenomatous goiter 20 years previously, was found to have pulmonary lesions on chest X-ray, a brain lesion on computerized tomography (CT), and elevated serum thyroglobulin (Tg). While completion thyroidectomy revealed that no pathological evidence of thyroid malignancy, radioiodine-avid pulmonary, brain, and renal and bone lesions were identified on diagnostic as well as posttherapy whole body planar scintigraphy and single photon emission computed tomography-CT. Subsequent ultrasonography-guided biopsy of a renal nodule showed thyroid follicular cells. This case suggests that metastatic differentiated thyroid carcinoma should be suspected in asymptomatic patients with incidentally detected lesions, raised serum Tg, and history of thyroid lesions.

Contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography in solid pseudopapillary neoplasm of the pancreas.

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare pancreatic tumor with low malignant potential. It occurs characteristically more often in young women. Radiological and pathological studies have revealed that the tumor is quite different from other pancreatic tumors. Limited information is available in the literature reporting their accumulation of fluorine-(18) fluorodeoxyglucose ((18)F-FDG) in positron emission tomography/computed tomography (PET/CT). Here, we report a case of pancreatic SPN imaged with contrast-enhanced FDG PET/CT. A percutaneous fine needle aspiration from the metabolically active lesion revealed SPN, and it was confirmed with histopathological results. Recurrence or metastasis was not found after 7 months of follow-up.

Noninvasive evaluation of active pan-ulcerative colitis with multiple strictures using Fluorine-18-Fluorodeoxyglucose positron emission tomography/computed tomography.

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by waxing and waning inflammation that changes in severity and extent and may progress to neoplasia, especially in the presence of strictures. When patients have nonnegotiable strictures or severe inflammation with ulcers, colonoscopy is difficult and carries the risk of perforation. The authors present a patient with pan-UC with multiple strictures, in whom fluorodeoxyglucose positron emission tomography/computed tomography was used to noninvasively evaluate the extent and severity of the disease.

Contrast-enhanced fluorodeoxyglucose positron emission tomography/contrast-enhanced computed tomography in mediastinal T-cell lymphoma with superior vena cava syndrome.

Positron emission tomography-computed tomography (PET/CT) is a routine investigation for the staging of lymphomas. Contrast-enhanced computed tomography is mandatory whenever parenchymal lesions, especially in the liver and spleen are suspected. We report a rare case of primary mediastinal T-cell lymphoma evaluated with contrast-enhanced PET/CT that showed features of superior vena cava syndrome.

Pancreatic tuberculosis: Evaluation of therapeutic response using F-18 fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography.

F-18 fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) is a functional imaging technique that monitors glucose metabolism in tissues. Pulmonary tuberculosis (TB) has been reported to show intense uptake of FDG, with a decrease in metabolism of the tuberculous lesions after successful anti-tubercular treatment (ATT). The authors present a patient with pancreatic TB and demonstrate the usefulness of FDG PET/CT in monitoring the response to ATT.

Pyrexia, Lung nodules, Granulomas: Pulmonary Lymphomatoid Granulomatosis.

The differential diagnosis of pyrexia, lung nodules and granulomas includes tuberculosis, vasculitis and rarely a malignancy. In countries where tuberculosis or histoplasmosis is endemic, these are the first consideration and often ruled out by microbiological investigations. Vasculitis like granulomatosis with polyangitis (Wegener's granulomatosis), Churg strauss syndrome and sarcoidosis, which are the second consideration, are ruled out by serological investigations. Confirmation of malignancy merits histopathology. This case highlights how a rare diagnosis of pulmonary lymphomatoid granulomatosis was reached after an open lung biopsy. The following case also describes the natural history of this rare disease as it showed transient spontaneous remission but ultimately required therapy.

Isolated cerebellar hypermetabolism on FDG PET in a case of remitted primary breast lymphoma.

We present here a case of primary non-Hodgkin's lymphoma of the breast that succumbed in a sub-acute course to death after three months of initial remission. The fluorodeoxyglucose positron emission tomography imaging during the declining clinical status showed isolated cerebellar hypermetabolism.