Metabolic tumor parameters complement clinicopathological factors in prognosticating advanced stage Hodgkin Lymphoma

Objective(s): Advanced Hodgkin Lymphoma has a higher probability of relapse and recurrence. Classical clinicopathological parameters including the International Prognostic Score (IPS) have not been reliable in predicting prognosis or tailoring treatment.  Since FDG PET/CT is the standard of care in staging Hodgkin Lymphoma, this study attempted to evaluate the clinical utility of baseline metabolic tumor parameters in a cohort of advanced Hodgkin lymphoma (stage III and IV).Methods: Histology-proven advanced Hodgkin Patients presenting to our institute between 2012-2016 and treated with chemo-radiotherapy (ABVD / AEVD) were followed up till 2019. Quantitative PET/CT and clinicopathological parameters were used to estimate the Event Free Survival (EFS) in 100 patients. Kaplan-Meier method with log-rank test was used to compare the survival times of prognostic factors.Results: At a median follow-up of 48.83 months (IQR:33.31-63.05 months), the five-year-EFS was 81%. Of the 100 patients, 16 had relapsed (16%) and none died at the last follow-up. On Univariate analysis, among non-PET parameters bulky disease (P=0.03) and B-symptoms (P=0.04) were significant while among PET/CT parameters SUVmax (p=0.001), SUVmean (P=0.002), WBMTV2.5 (P<0.001), WBMTV41% (P<0.001), WBTLG2.5 (P<0.001) and WBTLG41% (P <0.001) predicted poorer EFS.  5-year EFS for patients with low WBMTV2.5 [<1038.3 cm3] was 89% and 35% for patients with high WBMTV2.5 [≥1038.3 cm3] (p <0.001). In a multivariate model, only WBMTV2.5 (P=0.03) independently predicted poorer EFS.Conclusion: PET-based metabolic parameter (WBMTV2.5) was able to prognosticate and complement the classical clinical prognostic factors in advanced Hodgkin Lymphoma. This parameter could have a surrogate value for prognosticating advanced Hodgkin lymphoma. Better prognostication at baseline translates to tailored or risk-modified treatment and hence higher survival

A pictoral review on somatostatin receptor scintigraphy in neuroendocrine tumors: The role of multimodality imaging with SRS and GLUT receptor imaging with FDG PET-CT

Somatostatin receptor scintigraphy is considered as a comprehensive imaging modality for many neuroendocrine tumors. Multiple radiotracers using combinations of gamma or positron emitting radionuclides and tracers are now available. Newer radiopharmaceuticals using 99m Tc labeled with TOC, TATE, NOC are good alternatives to the 68 - Gallium radiotracers where the PET facility is not available. The pictoral depicts the role of SRS using 99mTC - HYNIC -TOC radiotracers in staging and treatment planning of NETs. Characterization of the tumor biology using combined SRS and FDG PET/CT is also demonstrated with a proposed categorization method. The emerging role of SRS in tailored targeted radionuclide therapy is outlined in brief

A rare variant of Caffey's disease – X-rays, bone scan and FDG PET findings

An 18-month-old boy with history of fever of 4 months duration and with swelling of the limbs was referred for a bone scan. There were multiple swellings over his upper and lower limbs, with bowing of the lower limbs. His radiological skeletal survey revealed marked periosteal new bone formation surrounding the diaphysis of long bones. A bone scan done with 99m Tc-MDP showed diffusely increased tracer uptake in all the long bones. A fluorodeoxyglucose positron emission tomography (FDG PET) scan done to assess the metabolic activity showed patchy FDG uptake in the long bones, ankle joint and anterior ends of few ribs. His clinical and imaging findings led to the diagnosis of Caffey's disease

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-Hodgkin′s lymphoma (NHL) n = 2, malignant melanoma n = 1]. In one patient, colonic uptake was diagnosed as inflammatory. The mean standardized uptake value max (SUV max ) for the 12 premalignant lesions was 16.9 ± 9.6 (range 7.5-37.4) and the mean SUV max for the 8 malignant lesions was 12.9 ± 5.5 (range 6.7-21.6). The difference in SUV max 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

A rare cause of tube arcing artifact seen in computed tomography image of a positron emission tomography/computed tomography scanner

Tube arcing artifact is known to be caused by a temporary short circuit in the X-ray tube causing momentary loss of X-ray output. It is seen as near-parallel and an equidistant streak pattern on transaxial computed tomography (CT) images and as a "horizontal" hypodense band on the coronal and sagittal CT images. This artifact can be a random occurrence and was caused in this particular case due to voltage fluctuations in the high-voltage supply transformer supplying the rotor of the anode in the X-ray tube. This problem was initially corrected by reducing the tube voltage to 120 kV from the original 140 kV and, subsequently, replacing the faulty transformer. This kind of artifact, which is a very rare situation, can affect the image quality, and could also be an early sign of equipment failure. To the authors' knowledge, such an artifact has not been reported till date in a clinical scenario. Hence, we would like to report a rare situation of tube arcing artifact along with a unique remedy. </p

PET reconstruction artifact can be minimized by using sinogram correction and filtered back-projection technique

Filtered Back-Projection (FBP) has become an outdated image reconstruction technique in new-generation positron emission tomography (PET)/computed tomography (CT) scanners. Iterative reconstruction used in all new-generation PET scanners is a much improved reconstruction technique. Though a well-calibrated PET system can only be used for clinical imaging in few situations like ours, when compromised PET scanner with one PET module bypassed was used for PET acquisition, FBP with sinogram correction proved to be a better reconstruction technique to minimize streak artifact present in the image reconstructed by the iterative technique