Diagnostic accuracy of RBC scintigraphy and CTA for detection of patients with suspected lower gastrointestinal bleeding: a systematic review and meta-analysis.

OBJECTIVE: Detection of lower gastrointestinal bleeding (LGIB) through noninvasive modalities is very important in the successful management of LGIB. RBC scintigraphy and CT have a role in the detection of LGIB and guiding the management of patient by localization of the bleeding site. However, only a small number of studies have evaluated the role of RBC scintigraphy and CT in the diagnosis of LGIB. This systematic review was conducted to evaluate the diagnostic performance of RBC scintigraphy and CT in the detection of LGIB in patients with clinical or biochemical findings suspicious of LGIB. METHODS: This systematic review followed PRISMA guidelines. Searches in PubMed, Scopus, and Embase were conducted using relevant keywords, and articles published through 30 April 2022, were included. Using endoscopy or surgical outcomes as the reference standard, the numbers of true and false positives and true and false negatives were extracted. Pooled estimates of diagnostic test accuracy - including sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and summary ROC (SROC) curve - were generated using bivariate random-effects meta-analysis. RESULTS: Three studies comprising 171 patients were included in the systematic review and meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using RBC scintigraphy were 0.787 (95% CI, 0.643-0.893), 0.289 (95% CI, 0.164-0.443), 1.214 (95% CI, 0.923-1.597) and 0.576 (95% CI, 0.296-1.121) respectively. The area under the SROC curve was 0.73. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using CT were 0.931 (95% CI, 0.772-0.992), 0.870 (95% CI, 0.737-0.951), 6.085 (95% CI, 0.840-44.097), 0.126 (95% CI, 0.006-2.509) respectively. The area under the SROC curve was 0.095. CONCLUSION: RBC scintigraphy has overall good sensitivity and CTA has excellent sensitivity specificity, positive and negative likelihood ratio in the detection of LGIB in patients with clinical or biochemical findings suspicious for LGIB.CTA along with RBC scintigraphy can be used algorithmically to rule out patients who do not have a localization for the site of LGIB thereby helping these patients to avoid invasive procedures like endoscopy or surgical explorations.

Utility of 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Cardiac Infections.

Diagnosis of cardiac infections, which includes infective endocarditis (IE) and cardiac device infections, despite having a high death rate, is still challenging. Frequently used modalities such as echocardiography, computed tomography (CT), and magnetic resonance imaging cannot confirm the presence of an active infection or extracardiac findings. Taking these things to consideration, newer guidelines have suggested the inclusion of 18F fluorodeoxyglucose positron emission tomography/CT (18F FDG PET/CT) in the workup of patients with suspected prosthetic valve IE. In this pictorial essay, we are demonstrating the utility of 18F-FDG PET/CT in varied cases of IE, cardiac implantable electronic devices, and coronary stent infection and how they helped in solving diagnostic dilemmas.

Semiquantitative evaluation of 68Ga-DOTANOC uptake in the normal myocardium: establishment of reference values.

BACKGROUND: To ascertain presence of physiological uptake and derive standardized uptake values (SUV) of 68Ga-DOTANOC in normal myocardium and establish reference values. METHODS AND RESULTS: Dedicated cardiac 68Ga-DOTANOC PET/CT studies of patients referred for evaluation of cardiac sarcoidosis (CS) or myocarditis and found to be normal on visual assessment and on cardiac MRI were analyzed semiquantitatively. The studies were acquired 45-60 minutes after intravenous injection of 111-185 MBq of 68Ga-DOTANOC. Myocardial SUVmax normalized to lean body mass (SUVmax_lbm) values for septum, anterior wall, proximal lateral wall, distal lateral wall, inferior wall, and apical region were 1.12 ± .39, 1.09 ± .42, 1.26 ± .49, 1.16 ± .40, 1.23 ± .39, and 1.05 ± .40, respectively. Myocardial SUVmax_lbm-to-blood pool SUVmean_lbm ratios were calculated for each region and 95th percentile values of these ratios were considered the upper limit of normal. 95th percentile values of myocardial SUVmax_lbm-to-blood pool SUVmean_lbm ratio for the corresponding regions were 1.70, 1.70, 2.00 1.95, 2.05, and 1.70, respectively. CONCLUSION: There can be physiological uptake of 68Ga-DOTANOC in normal myocardium and the reference values of semiquantitative parameters established in this study may be employed as a corroborative tool for visual assessment in patients undergoing 68Ga-DOTANOC PET/CT for suspected CS or myocarditis.

Tc-99m Ethambutol Scintigraphy with Single-Photon Emission Computed Tomography in Diagnosis of Tubercular Iliopsoas Abscess.

Very few imaging techniques can demonstrate the presence of Mycobacterium tuberculosis in vivo. Technitium-99m Ethambutol scintigraphy is one of them, although literature on the utility of this technique is scarce. We describe a patient with iliopsoas abscess showing increased uptake on Tc-99 m ethambutol scintigraphy which was later confirmed to be tubercular by the microbiological analysis of pus.

Serendipitous Diagnosis of Tertiary Hyperparathyroidism in a Case Purportedly thought to have Skeletal Metastases.

Tertiary hyperparathyroidism (THPT) is characterized by over secretion of parathyroid hormone caused by long-standing secondary hyperparathyroidism. THPT can affect the bones as well as cause extraskeletal calcifications. The bony lesions often mimic multiple skeletal metastases or multiple myeloma. We report a case of a 48-year-old man with chronic kidney disease on dialysis, who presented with chief complaints of low back ache and swelling over the left clavicle. In view of clinical suspicion of malignancy with bony metastases, he underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomography and was subsequently found to have parathyroid adenomas, which were confirmed on 99mTc-methoxy-isobutyl-isonitrile scintigraphy.

Infected Lower Limb Megaprosthesis on 68Ga-NOTA-Ubiquicidin PET/CT Imaging.

Pain after prosthesis implant is a common clinical problem which requires distinction of septic from aseptic causes since the treatment differs. Non-invasive imaging methods play an important role in the diagnosis. Radiolabelled ubiquicidin can be used for imaging infection by binding directly to bacterial cell wall. We describe a case of a 24-year-old man with right lower limb megaprosthesis which did not show any loosening on computed tomography (CT) but was accurately diagnosed as infected prosthesis with 68Ga-NOTA-ubiquicidin(29-41) acetate scan.

Incidentally Detected High SSTR Expression in Uterine Leiomyoma on DOTANOC PET/CT.

ABSTRACT: A 38-year-old woman with a 2-month history of per vaginal bleeding and episodes of palpitations, headache, and vomiting underwent 68Ga-DOTANOC PET/CT for evaluation, which revealed a left suprarenal mass and a large uterine mass, both of which were intensely tracer avid. Histopathology of the masses after surgery revealed a left pheochromocytoma and uterine leiomyoma. SSTR-expressing leiomyoma is an uncommon finding and must be kept in mind as a differential diagnosis of DOTANOC-avid uterine mass.

Comparison of 68Ga-DOTANOC PET/CT with cardiac MRI in patients with clinical suspicion of cardiac sarcoidosis.

BACKGROUND: 68Ga-DOTA-NaI-octreotide (DOTANOC) is a promising new alternative to 18F-fluorodeoxyglucose (FDG) for imaging inflammation in cardiac sarcoidosis. The aim of the study was to compare 68Ga-DOTANOC positron emission tomography/computed tomography (PET/CT) with cardiac magnetic resonance imaging (CMR) in patients with clinical suspicion of cardiac sarcoidosis. METHODS AND RESULTS: Patients with extracardiac sarcoidosis and clinical suspicion of cardiac involvement underwent 68Ga-DOTANOC cardiac PET/CT, myocardial perfusion single photon emission computed tomography (MPS) and CMR (T2-weighted and delayed gadolinium-enhanced T1-weighted images). The patients were screened using revised criteria of Japanese circulation society. Presence of perfusion defects on MPS, abnormal myocardial uptake on 68Ga-DOTANOC PET/CT and characteristic pattern of late gadolinium enhancement (LGE) with or without T2 hyperintensity on CMR was considered positive. RESULTS: Seventeen patients (13 male and 4 female) were included in the study. Out of the 17 patients, both CMR and PET were positive in 11 and both were negative in 2. In the remaining 4 patients, CMR was positive but PET was normal. Thus, PET and CMR were concordant in 13 (76.5%) patients and discordant in 4 (23.5%). Intermodality agreement was fair (Cohen's kappa = 0.39). CONCLUSION: LGE on CMR is superior to 68Ga-DOTANOC PET/CT for detecting cardiac involvement in sarcoidosis and there is fair concordance between the two. However, since LGE does not specifically differentiate between inflammation and fibrosis, 68Ga-DOTANOC PET/CT may be better than CMR in identifying patients with active inflammation, since it directly targets inflammatory cells and can have a complementary role to CMR.

Low-Grade Thymoma with Osseous and Pulmonary Metastases: Role of 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Initial Staging.

Thymomas are rare anterior mediastinal tumors that originate in the epithelial cells of the thymus and have a rare propensity to metastasize to extrathoracic locations unless it is a histologic high-grade neoplasm (type B and above). We describe a case of 50-year-old woman diagnosed with type AB thymoma and the role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography in accurate delineation of extrathoracic metastases during initial staging.