Background: Lower Gastrointestinal bleeding (LGIB) is a serious and urgent condition which can be assessed using several different modalities. Tc-99m tagged RBC scintigraphy has been established as a diagnostic tool in Nuclear Medicine but several other modalities, including CT-based imaging (i.e. angiography) currently exist. Objective: The objective of this study is to compare Tc-99m tagged RBC scintigraphy with CT-based imaging studies in terms of clinical utility and diagnostic outcomes. Methods: A systematic review of available literature was done, with the goal of creating a meta-analysis focusing on the reported diagnostic outcomes - mainly sensitivity and specificity on the presence of a LGIB. Aside from this, a systematic review of the clinical utility and the differences of each test were discussed, including non-quantifiable advantages. The literature search was conducted following the guidelines of PRISMA, with searches from PubMed, Medline, and other pertinent databases. Quality assurance was done using the QUADAS tool. Statistical analyses of sensitivity, specificity, and a summary receiver operating characteristics plot were computed for the meta-analysis. Results: Pooled sensitivity and specificity for RBC scintigraphy were 0.886 and 0.119, respectively. Pooled sensitivity and specificity for CT-based imaging were 0.729 and 0.660, respectively. CT based imaging also showed higher localization and faster completion times. RBC scintigraphy had a longer acquisition window. Conclusion Both Tc99m-tagged RBC scintigraphy and CT-based imaging have important clinical utility, with each modality having different advantages that the other test cannot provide.
Computed Tomography Angiography