Archi Agrawal

A novel approach for reduction of brown fat uptake on FDG PET

The aim of this study was to determine whether or not a single dose of a beta-blocker, such as propranolol 40 mg, administered 60 min prior to (18)F-fluorodeoxyglucose ((18)F-FDG) injection would help reduce brown fat uptake of (18)F-FDG. Patients who were referred for either a pre-treatment or a post-treatment evaluation positron emission tomography (PET) scan and who showed (18)F-FDG uptake in brown adipose tissue (BAT) were included in this study. The total number of patients who showed uptake in BAT and in whom a repeat study was carried out after propranolol injection was 40. A repeat PET scan was carried out after an interval of at least 48 h. Propranolol at a dose of 40 mg was given orally 60 min prior to the (18)F-FDG injection. A whole-body PET scan was performed on a dedicated whole-body PET scanner (ADVANCE, GE Medical Systems, Milwaukee, WI), using attenuation correction with 68-Ge external pin sources. We observed that (18)F-FDG uptake in BAT was absent in 36 (90%) patients post propranolol. We conclude that propranolol reduces the uptake of (18)F-FDG in BAT, and thus improves the accuracy of PET imaging.

18F-FDG PET/CT-directed biopsy: does it offer incremental benefit?

PurposeTo study whether the metabolic information provided by a prior PET/computed tomography (CT) scan can add valuable information and an incremental benefit while performing image-guided biopsies. MethodsFluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT findings of 112 patients were available before biopsy and were considered for analysis. Biopsies were performed using standard techniques only after the needle tip was confirmed to be in the portion of the lesion corresponding to the hypermetabolic area seen on PET. This was achieved by visual coregistration and also by software registration algorithms that registered the intraprocedural CT images with the preselected PET/CT data. Only those biopsies for which a definitive histopathological diagnosis could be made were considered ‘diagnostic’. Cases in which PET/CT added an incremental value were divided into three categories. ResultsA total of 112 patients (66 male and 46 female, age range 16–74 years) underwent a biopsy based on PET findings. The biopsy sites were as follows: lung, 54; lymph nodes, 27; bone, 12; and soft-tissue masses/deposits, 19. Out of the 112 biopsies, an incremental benefit was seen overall in 53 patients (47.3%): in 40.7% (22/54) of patients who underwent lung biopsies, 44.4% (12/27) of those who underwent lymph node biopsies, 66.6% (8/12) of those who underwent bone biopsies and 57.8% (11/19) of those who underwent soft-tissue biopsies. Out of the cases that showed an incremental benefit, the highest number (30) belonged to the category in which the biopsy sample was obtained from the focal hypermetabolic portion of the apparently larger morphological lesion seen on CT. ConclusionPET/CT data coregistered with intraprocedural CT images can guide needle placement in the viable portion of the lesion, thus increasing the chances of achieving a definitive diagnosis. This approach can offer a significant incremental benefit while performing image-guided biopsies.

90Y microsphere therapy: does 90Y PET/CT imaging obviate the need for 90Y Bremsstrahlung SPECT/CT imaging?

BackgroundTransarterial radioembolization using 90Y microspheres is a novel therapeutic option for inoperable hepatic malignancies. As these spheres are radiolucent, real-time assessment of their distribution during the infusion process under fluoroscopic guidance is not possible. Bremsstrahlung radiations arising from 90Y have conventionally been used for imaging its biodistribution. Recent studies have proved that sources of 90Y also emit positrons, which can further be used for PET/computed tomography (CT) imaging. This study aimed to assess the feasibility of 90Y PET/CT imaging in evaluating microsphere distributions and to compare its findings with those of Bremsstrahlung imaging. Materials and methodsThirty-five sessions of 90Y microsphere transarterial radioembolization were performed on 30 patients with hepatic malignancies. 90Y PET/CT imaging was performed within 3 h of therapy. Bremsstrahlung imaging was also performed for each patient. The imaging findings were compared for concordance in the distribution of microspheres. ResultsExact one-to-one correspondence between 90Y PET/CT imaging and 90Y Bremsstrahlung imaging was observed in 97.14% of cases (i.e. in 34/35 cases). Discordance was observed only in one case in which 90Y PET/CT imaging resolved the microsphere uptake in the inferior vena cava tumor thrombus, which was, however, not visualized on Bremsstrahlung imaging. ConclusionThere is good concordance in the imaging findings of 90Y PET/CT and 90Y Bremsstrahlung imaging. 90Y PET/CT imaging scores over the conventionally used Bremsstrahlung imaging in terms of better resolution, ease of technique, and comparable image acquisition time. This makes it a preferred imaging modality for assessment of the distribution of 90Y microspheres.

Etiology and significance of incidentally detected focal colonic uptake on FDG PET/CT.

Background: Incidental colonic uptake of 18F-flurodeoxyglucose (FDG) is not an infrequent finding encountered during whole body positron emission tomography (PET) imaging. Almost all studies on this topic are in Western populations, which have a markedly different epidemiological profile for colorectal premalignant and malignant conditions as compared to that of the Indian subcontinent. Aim: The purpose of this study was to assess the etiology of incidentally detected focal FDG uptake in the colon by comparing it with colonoscopy and histopathology. Materials and Methods: Electronic medical records of patients who underwent FDG PET/computed tomography (CT) at our institution for a 2½-year period from January 2009 to July 2011 were reviewed. There were 32 out of 9000 (0.35%) patients whose PET/CT reports mentioned incidental focal colonic FDG uptake, of which 24 patients subsequently underwent colonoscopy. Lesions which appeared neoplastic on colonoscopy were confirmed with histopathology obtained after biopsy or surgery. Colonoscopy and pathology findings were considered as gold standard. Results: Among the 24 patients who underwent a colonoscopy, 3 patients had normal findings (12.5%). A positive colonoscopy was noted in 21 patients (87.5%) with the lesion coinciding with the location described in the PET/CT report. Adenomatous polyps were detected in 12 patients (37.5%), whereas in 8 patients (25%) malignant lesions were confirmed [adenocarcinoma n = 5, non-Hodgkins lymphoma (NHL) n = 2, malignant melanoma n = 1]. In one patient, colonic uptake was diagnosed as inflammatory. The mean standardized uptake valuemax (SUVmax) for the 12 premalignant lesions was 16.9 ± 9.6 (range 7.5-37.4) and the mean SUVmax for the 8 malignant lesions was 12.9 ± 5.5 (range 6.7-21.6). The difference in SUVmax between the premalignant adenomatous polyps and the malignant lesions was not statistically significant (P = 0.316). Conclusions: Our study shows that a significant proportion of patients (62.5%, 20/32) showing an incidental focal FDG uptake will harbor premalignant (adenomatous polyps) or malignant lesions, and further evaluation with colonoscopy and biopsy is warranted in such cases.

Appropriateness criteria of FDG PET/CT in oncology

18Fluorine-2-fluoro-2-Deoxy-d-glucose (18F-FDG) positron emission tomography/computerized tomography (PET/CT) is a well-established functional imaging method widely used in oncology. In this article, we have incorporated the various indications for 18FDG PET/CT in oncology based on available evidence and current guidelines. Growing body of evidence for use of 18FDG PET/CT in select tumors is also discussed. This article attempts to give the reader an overview of the appropriateness of using 18F-FDG PET/CT in various malignancies.

Imaging findings in a rare case of extra-articular chondrocalcinosis.

We report the imaging findings in extra-articular chondrocalcinosis in a 53-year-old man with swelling and pain in right scapular area for 1 year. Plain radiography showed a right scapular area calcific mass. The clinical suspicion was of a soft tissue sarcoma. As a part of diagnostic workup, a bone scan and a PET/CT scan were done. Bone scan revealed intense MDP uptake in the right scapular area. FDG PET/CT revealed intense FDG uptake in the mass. The biopsy revealed chondrocalcinosis. This is an addition to our long list of causes of extraosseous uptake of MDP.

Prospective study of ultrasound-guided fine-needle aspiration cytology and sentinel node biopsy in the staging of clinically negative T1 and T2 oral cancer.

The purpose of this study was to compare sentinel node biopsy (SNB) and ultrasound‐guided fine‐needle aspiration cytology (FNAC) for preoperative evaluation of the N0 neck in T1 to T2 oral cavity squamous cell carcinoma (SCC).

Unsuspected second malignancy detection by FDG PET scan.

A whole body F-18 FDG PET scan was done on a 45-year-old man with a small cell carcinoma of the left lung for a metastatic survey. Imaging showed intense uptake in the left lung (maximum standardized uptake value (SUVmax) of 8.32 corrected for body weight), at the site of the primary and in the hilar lymph nodes. Focal intense uptake was also seen in the rectum (SUVmax of 21.73 corrected for body weight). No anatomic imaging for the pelvis was done, as the patient had no bowel symptoms. Posttreatment PET scan done 9 months after the first scan showed significant reduction in the primary mass in the lung (SUVmax 4.45) but an increase in the rectal mass (SUVmax 83.22). He now complained of bleeding per rectum. Colonoscopy and CT scan of the abdomen showed a mass in the rectum, which on biopsy revealed invasive adenocarcinoma.

Incremental value of 18F-FDG PET/CT in therapeutic decision-making of potentially curable esophageal adenocarcinoma.

Aims and objectivesThe aim of the study was to estimate the incremental value of fluorine-18 fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) in aiding treatment decisions in a specific cohort of patients with lower esophageal and gastroesophageal junction adenocarcinoma who were considered for potentially curative treatment on the basis of conventional imaging. Materials and methodsThe study included patients referred for a staging 18F-FDG PET/CT who were considered for potentially curative treatment (neoadjuvant therapy followed by surgery or definitive chemoradiotherapy) by a multidisciplinary tumor board. The proportion of patients with M1b disease (American Joint Committee on Cancer, 6th ed.) detected on 18F-FDG PET/CT was calculated. The sensitivity, specificity, positive and negative predictive values, and accuracy of 18F-FDG PET/CT for M1b disease were calculated. PET/CT findings were verified with histopathological analysis; when it was not possible to obtain pathological confirmation, correlative imaging or follow-up imaging studies were used for validation. ResultsA total of 156 patients who fulfilled the inclusion criteria were analyzed. 18F-FDG PET/CT detected M1b disease in 25 patients (16%), changing the intent of treatment from potentially curative to palliative. In five patients, PET/CT failed to detect distant metastases. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-FDG PET/CT for detecting M1b disease were 83.3, 98.4, 92.5, 96.1, and 95.3%, respectively. Additional surgical procedures (hemicolectomy and polypectomy) were performed in three patients because of the detection of a second primary cancer in the colon in two patients and a colonic dysplastic polyp in one patient. ConclusionIn patients who are considered to be potentially curable after conventional imaging, 18F-FDG PET/CT can detect unsuspected sites of distant metastases (M1b) in a significant number of cases and thus contribute to the clinical decision-making process. PET/CT should be an integral part of the staging workup of patients with esophageal adenocarcinoma.

Interesting image. The search for primary tumor in a patient with oncogenic osteomalacia: F-18 FDG PET resolves the conundrum.

Abstract: We report a case of oncogenic osteomalacia in which F-18 FDG PET imaging played a crucial role in detecting the occult neoplasm. A 39-year-old female patient presented with low backache and bilateral lower limb pain of 3-year duration. On evaluation, she was found to have hypophosphatemic osteomalacia and was referred for F-18 FDG PET scan because her initial clinical and radiologic evaluation failed to detect a tumor. F-18 FDG PET scan revealed a hypermetabolic focus in right popliteal fossa, which was correlated as a tumor in soft tissues of right popliteal fossa on magnetic resonance imaging. Following surgical excision of tumor, final histopathology revealed a benign phosphaturic mesenchymal tumor of mixed connective tissue origin. Postoperatively, her symptoms alleviated and serum phosphates normalized within 2 weeks. We suggest that F-18 FDG PET should be performed in such cases to localize occult neoplasm that may be otherwise missed on conventional radiologic imaging.