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Case Reports
. 2025 Jan 29;20(4):2080-2086.
doi: 10.1016/j.radcr.2024.12.016. eCollection 2025 Apr.

Case series review illustrating the utility of SPECT/CT in enhancing reader confidence and avoiding pitfalls in interpreting 99mTc-labeled red blood cell scans

Jeremy Hugh Yen-Hey Lau  1 , Koon Kiu Ng  1 , Wai Chung Wong  1 , Boom Ting Kung  1
Affiliations
Case Reports

Case series review illustrating the utility of SPECT/CT in enhancing reader confidence and avoiding pitfalls in interpreting 99mTc-labeled red blood cell scans

Jeremy Hugh Yen-Hey Lau et al. Radiol Case Rep. .

Abstract

Gastrointestinal bleeding is a common condition requiring urgent medical attention. 99mTc-labeled red blood cell scintigraphy is a conventional nuclear medicine imaging technique which is sensitive and noninvasive for diagnosing occult gastrointestinal bleeding. However, there are pitfalls in this technique due to 2D representation in planar images and altered biodistribution in certain physiological status of the patient. The anatomical localization of single-photon emission computerized tomographycomputed tomography (SPECT/CT) can avoid these pitfalls and reduce equivocal findings in Tc99m-labeled red blood cell scintigraphy. This case series review demonstrates equivocal findings in 99mTc-labeled red blood cell scintigraphy, with the help of SPECT/CT, were found to be possible blood pooling in vasculatures and hemolysis after blood transfusion.

Keywords: Gastrointestinal bleed; Single-photon emission computerized tomography-computed tomography (SPECT/CT); Tc99m-labeled red blood cell scintigraphy.

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Figures

Fig 1:
Fig. 1
Case 1 with mild transverse linear tracer accumulation in upper abdominal region (arrow) was seen in (a) blood pool images with increase in intensity in (b) dynamic image up to 1-hour postinjection. Persistent of the above-mentioned accumulation of activity was seen up to (c) 6.5 hours.
Fig 2:
Fig. 2
SPECT/CT of case 1 at 6.5 hours reveals activity pooling in left renal vein (arrow). (A) CTonly image, (B) SPECT only image, (C) SPECT/CT fusion image and (D) maximal intensity projection image.
Fig 3:
Fig. 3
Case 2 with the (A) blood pool and dynamic images appear unremarkable. Curvilinear transverse increased tracer uptake (arrow) following conformity of transverse colon was seen from (B) 3 hours and persistent in (C) 5-hour image.
Fig 4:
Fig. 4
SPECT/CT of case 2 at 3 hours reveals activity pooling in coeliac trunk and its subsidiaries (splenic artery and common hepatic artery, arrow). (A) CT only image, (B) SPECT only image, (C) SPECT/CT fusion image and (D) maximal intensity projection image.
Fig 5:
Fig. 5
Case 3 showed no abnormal focus found in (A) dynamic and (B) delayed planar images up to (C) 7-hour postinjection. Accumulation of activity is seen at inferior border of liver in right upper quadrant at (D, arrow) 24 hours.
Fig 6:
Fig. 6
SPECT/CT of case 3 at 24 hours reveals activity pooling in gallbladder (arrow). (A) CT only image, (B) SPECT only image, (C) SPECT/CT fusion image and (D) maximal intensity projection image.
See this image and copyright information in PMC

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