Radiologic Assessment of Gastrointestinal Bleeding

Engineered Bacteria for Visualization and Localization of Gastrointestinal Bleeding: A Promising Application

Gastrointestinal bleeding, especially obscure gastrointestinal bleeding (OGIB), is a common and serious clinical emergency with a notable incidence rate. However, the current diagnostic method, gastroscopy, is invasive and often struggles to efficiently detect microhemorrhagic lesions, leading to diagnostic challenges and potential misdiagnoses. Here, we developed an intelligently engineered bacterium utilizing synthetic biology techniques for in vivo localization detection of gastrointestinal bleeding. By constructing three gene circuit modules within E. coli Nissle 1917 for heme recognition, response, and output generation, we have successfully enabled specific heme sensing and real-time optical signal production in vivo. This innovative strategy overcomes the limitations of the existing diagnostic methods, offering a noninvasive and precise means of detecting gastrointestinal bleeding. These advancements hold promise for enhancing diagnostic accuracy and treatment efficacy in future clinical settings within the realm of gastroenterology.

Diagnosis of Occult and Obscure Gastrointestinal Bleeding

Occult and obscure bleeding are challenging conditions to manage; however, recent advances in gastroenterology and endoscopy have improved our diagnostic and therapeutic capabilities. Obscure gastrointestinal (GI) bleeding is an umbrella category of bleeding of unknown origin that persists or recurs after endoscopic evaluation of the entire bowel fails to reveal a bleeding source. This review details the evaluation of patients with occult and obscure GI bleeding and offers diagnostic algorithms. The treatment of GI bleeding depends on the type and location of the bleeding lesion and an overview of how to manage these conditions is presented.

Real-time multi-contrast magnetic particle imaging for the detection of gastrointestinal bleeding

Gastrointestinal bleeding, as a potentially life-threatening condition, is typically diagnosed by radiation-based imaging modalities like computed tomography or more invasively catheter-based angiography. Endoscopy enables examination of the upper gastrointestinal tract and the colon but not of the entire small bowel. Magnetic Particle Imaging (MPI) enables non-invasive, volumetric imaging without ionizing radiation. The aim of this study was to evaluate the feasibility of detecting gastrointestinal bleeding by single- and multi-contrast MPI using human-sized organs. A 3D-printed small bowel phantom and porcine small bowel specimens were prepared with a defect within the bowel wall as the source of a bleeding. For multi-contrast MPI, the bowel lumen was filled with an intestinal tracer representing an orally administered tracer. MPI was performed to evaluate the fluid exchange between the vascular compartment of the bowel wall and the lumen while a blood pool tracer was applied. Leakage of the blood pool tracer was observed to the bowel lumen. Multi-contrast MPI enabled co-registration of both tracers at the same location within the bowel lumen indicating gastrointestinal bleeding. Single- and multi-contrast MPI are feasible to visualize gastrointestinal bleeding. Therefore, MPI might emerge as a useful tool for radiation-free detection of bleeding within the entire gastrointestinal tract.

Computed tomography angiography and three-dimensional reconstruction of renal arteries in diagnosing the bleedings after mini-percutaneous nephrolithotomy: a single-center experience of 7 years

OBJECTIVE

This study aimed to investigate the role of computed tomography angiography (CTA) and three-dimensional reconstruction of renal arteries in the evaluation of bleeding after mini- percutaneous nephrolithotomy (PCNL).

METHODS

31 consecutive patients with continuous renal hemorrhage after mini-PCNL were enrolled from January 2015 to January 2022. Demographic and clinical data were retrospectively recorded and analyzed. All patients had received CTA evaluation and subsequently digital subtraction angiography (DSA) embolization to manage renal bleeding. CTA and 3D reconstruction of renal arteries were performed using the 320 multi-detector computed tomography technique and the images were evaluated by experienced radiologists. DSA embolization were performed by an interventional radiologist with more than 10 years of experiences.

RESULTS

CTA and 3D construction of renal arteries showed 28 cases of vascular lesions (28/31, 90.3%), including 15 cases of pseudoaneurysm (15/28, 53.6%), 9 cases of arteriovenous fistula (9/28, 32.1%), and 4 cases of suspicious bleeding spot (4/28, 14.3%). While DSA revealed 31 cases of vascular lesions (100%), including 15 cases of pseudoaneurysm (15/31, 48.4%), 10 cases of arteriovenous fistula (10/31, 32.3%), 6 cases of bleeding spot and (6/31, 19.4%). The serum creatinine level was elevated slightly before mini-PCNL and after DSA embolization (73.1±18.1 vs 92.1±33.6, p<0.01). 15 patients (15/31, 48.4%) required blood transfusion, with mean blood transfusion volume of 700±660 ml (range, 400-1800ml). The bleeding was controlled without any further severe complications.

CONCLUSIONS

CTA and 3D reconstruction of renal arteries were safe and effective in diagnosing renal arterial bleedings after mini-PCNL, with a sensitivity of 90.3% and a specificity of 100%.

The utilization of CTA in management of gastrointestinal bleeding in a tertiary care center ED. Are we using it enough?

BACKGROUND

Gastrointestinal (GI) bleeding is a common patient presentation to the Emergency Department (ED) and the source can be difficult to diagnose.

PROCEDURE

Computed tomography angiography (CTA) is a new but validated modality with high sensitivity and specificity for diagnosis and treatment of GI bleeds, especially in differentiating arterial from venous bleeding. With high reported validity of CTA, some studies have suggested its ability to better triage patients in the ED and impact ED workflow and resource utilization. We evaluated the use of CTA use an academic tertiary care center ED for GI bleeding.

FINDINGS

Retrospective chart review of 1493 patient (2012-2015), one - way ANOVA, and one-tail t-test, found CTA is used significantly less (0.7%) compared to classical endoscopy (75.7%, p < .001), video capsule endoscopy (VCE)(4.8%, p < .001), tagged red blood cell scintigraphy(4.4%, p < .001), and traditional catheter-directed angiography(2.88%, p < .001). In our subset of 11 CTA cases, we found mean time (in hours) to CTA was faster than mean time to endoscopy, 31:47 [95% CI: -7:50-71:24] and 42:44 [95% CI: 18:27-67:01] respectively. The difference in means between time to CTA and time to endoscopy did not achieve statistical significance, 12:57 h [95% CI -18:51-44:45; p = .40].

CONCLUSION

We concluded that in light of its validation against these other diagnostic modalities, CTA may be underutilized in the care of patients with GI bleeding and should be studied further to study its impact on early risk stratification, treatment, and resource utilization.

Dual-energy CT evaluation of gastrointestinal bleeding

Gastrointestinal bleeding is a common cause for hospital admissions and is an important cause of morbidity and mortality. Although endoscopy is accepted as the standard initial diagnostic modality for the evaluation of gastrointestinal bleeding, multiphasic computed tomography (CT) imaging has become an alternative diagnostic tool. Dual-energy CT with post-processing techniques may have additional advantages over single-energy computed tomography in evaluation of gastrointestinal bleeding. In this article, we discuss the role of dual-energy CT in the evaluation of gastrointestinal bleeding with potential advantages over conventional CT and limitations.