Computed tomography versus digital subtraction angiography for the diagnosis of obscure gastrointestinal bleeding

Color-coded parametric imaging support display of vessel hemorrhage-an in vitro experiment and clinical validation study

Background

Digital Subtraction Angiography (DSA) is currently the most effective diagnostic method for vascular diseases, but it is still subject to various factors, resulting in uncertain diagnosis. Therefore, a new technology is needed to help clinical doctors improve diagnostic accuracy and efficiency.

Purpose

The objective of the study was to investigate the effect of utilizing color-coded parametric imaging techniques on the accuracy of identifying active bleeding through DSA, the widely accepted standard for diagnosing vascular disorders.

Methods

Several variables can delay the diagnosis and treatment of active bleeding with DSA. To resolve this, we carried out an in vitro simulation experiment to simulate vascular hemorrhage and utilized five color-coded parameters (area under curve, time to peak, time-of-arrival, transit time, and flow rate of contrast agent) to determine the optimal color coding parameters. We then verified it in a clinical study.

Results

Five different color-coded parametric imaging methods were compared and the time-of-arrival color coding was the most efficient technique for diagnosing active hemorrhage, with a statistically significant advantage (P < 0.001). In clinical study, 135 patients (101 with confirmed bleeding and 34 with confirmed no bleeding) were collected. For patients whose bleeding could not be determined using DSA alone (55/101) and whose no bleeding could not be diagnosed by DSA alone (35/55), the combination of time-of-arrival color parametric imaging was helpful for diagnosis, with a statistically significant difference (P < 0.01 and P = 0.01).

Conclusions

The time-of-arrival color coding imaging method is a valuable tool for detecting active bleeding. When combined with DSA, it improves the visual representation of active hemorrhage and improves the efficiency of diagnosis.

Management and outcomes of pseudoaneurysms presenting with late hemorrhage following pancreatic surgery: A six-year experience from a tertiary care center

BACKGROUND/PURPOSE

Late hemorrhage following pancreatic surgery is associated with significant morbidity and mortality. Pseudoaneurysm (PSA) is an important source of late hemorrhage, which is effectively and safely managed by embolization. We aim to retrospectively review the outcomes of embolization for pseudoaneurysms causing late post-pancreatectomy hemorrhage over a period of six-years at our tertiary care center.

METHODS

Between 2014 and 2020, 616 pancreatic surgeries were performed and 25 patients had late hemorrhage (occurring > 24 hours post-operatively). The clinical parameters related to late hemorrhage, associated complications, embolization details, treatment success and their short-and long-term outcomes were analyzed.

RESULTS

Sixteen of 25 patients had PSA on digital subtraction angiography. Embolization was performed in these patients with technical and clinical success rates of 94.1% and 100%, respectively. Compared to patients without PSA, patients with PSA had significant hemoglobin drop (2.5 g/dL vs. 1.5 g/dL, p = 0.01), higher incidence of sentinel bleed (50% vs. 11.1%, p = 0.05) and lower requirement for surgery for bleeding (0% vs. 44.4%, p = 0.02). Clincally relevant postoperative pancreatic fistula and bile leak were seen in 72% and 52% of patients, respectively. Eight of these embolized patients died due to sepsis. The long-term outcome was good, once the patients were discharged.

CONCLUSION

Late hemorrhage after pancreatic surgery was associated with high mortality due to complications such as pancreatic fistula and bile leak. Sentinel bleeding was an important clinical indicator of PSA. Angiographic embolization is safe and effective without any adverse short or long-term outcomes.

The utility of using TACE-assisted software with CBCT in colonic diverticular bleeding without extravascular leakage

The utility of three-dimensional (3D) imaging with cone-beam computed tomography (CBCT) during interventional radiology (IVR) in colonic diverticular bleeding was compared to that of contrast-enhanced computed tomography (CECT). Additionally, to identify the responsible vessels in the absence of extravascular leakage using digital subtraction angiography, we examined the detection rate using software conventionally applied to transcatheter arterial chemoembolization (TACE). The 3D images obtained by CECT before IVR did not clearly show the destroyed vessels, whereas the 3D images obtained by CBCT during IVR clearly depicted the peripheral vessels. The TACE-assisted software identified the responsible vessels with a high probability, even in cases without extravascular leakage. CBCT could delineate vascular positions more accurately than CECT. Moreover, 80% of the responsible vessels could be delineated using the software; however, caution should be exercised as results may differ depending on the positioning of the region of interest.

ACR Appropriateness Criteria® Radiologic Management of Lower Gastrointestinal Tract Bleeding: 2021 Update

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

CTA measurements of acute lower gastrointestinal bleeding size predict subsequent positive catheter angiography

PURPOSE

The purpose of this study was to determine whether the measured size of active gastrointestinal hemorrhage was useful in predicting subsequent positive findings at catheter angiography.

MATERIALS AND METHODS

This was a single-institution retrospective study consisting of 32 patients with computed tomography angiography (CTA) positive for gastrointestinal bleeding who went on to receive catheter angiography. Each CTA was reviewed, with axial measurements of the anterior-posterior and transverse dimensions of the largest foci of hemorrhage recorded. Volumetric analysis was used to measure the volume of hemorrhage. These measurements were performed for both the arterial and portal venous phases. Additionally, the interval growth between the arterial and portal venous phase was also calculated.

RESULTS

There was a statistically significant difference in the absolute size of the maximum transverse dimension on portal venous phase imaging (mean = 19.8 mm, p < 0.001), as well as an interval increase in transverse (mean = 8.5 mm, p < 0.001) and anteriorposterior (mean = 5.4 mm, p = 0.027) size between arterial and portal venous phases in patients with positive catheter angiography versus negative catheter angiography. There was a statistically significant difference in the volume of hemorrhage on arterial (mean = 1.72 cm³, p = 0.020) and portal venous phases (mean = 5.89 cm³, p = 0.016), as well as an interval change in the size of hemorrhage between the two phases (mean = 4.17 cm³, p = 0.020) in patients with positive catheter angiography versus patients in the negative catheter angiography group.

CONCLUSIONS

The absolute axial size and volume of hemorrhage, as well as the interval change between the arterial and portal venous phases of CTA imaging is predictive of subsequent positive catheter angiography.

Aortoenteric fistula: a rare but critical cause of small bowel bleeding discovered on capsule endoscopy

A 78-year-old man attended for outpatient capsule endoscopy, to investigate a recent history of unexplained small bowel bleeding. His previous medical history included an abdominal aortic aneurysm repair 6 years ago. Soon after capsule ingestion, he experienced sudden onset abdominal pain and collapsed on hospital grounds. He was rapidly transferred to the emergency department as he was haemodynamically unstable, and a significant per rectum (PR) bleed was found on examination. The patient was quickly stabilised following fluid resuscitation. CT angiography was performed which did not show active bleeding. However, use of the real-time capsule viewer indicated a profuse active jejunal bleed originating from the aortic graft, suggestive of an aortoenteric fistula. The patient underwent emergency endovascular cuff placement, and subsequent endovascular abdominal aortic stent grafting, to good effect.

Cone beam computed tomography improves the detection of injured vessels and involved vascular territories in patients with bleeding of uncertain origin

OBJECTIVE

The purpose of this preliminary retrospective study was to analyse if cone beam CT (CBCT) is able to identify more bleeding sites and corresponding feeding arteries in patients with haemorrhage of uncertain origin.

METHODS

In 18 vascular territories (16 patients), pre-interventional CT angiography (CTA) and selective angiograms resulted in discordant information regarding the suspected bleeding site and hence received CBCT. Image data of CTA and selective angiograms in comparison to CBCT were independently reviewed by two interventional radiologists. Image quality, diagnostic confidence, number of bleeding sites and involved vascular territories were investigated. Additionally, the correlation between number of bleeding sites and involved vascular territories with a  clinical gold-standard (super-selective angiographic findings and definitive clinical outcomes) was analysed.

RESULTS

Overall, subjective image quality did not significantly differ between investigated imaging modalities. However, CBCT significantly improved diagnostic confidence in both readers in detecting bleeding vessel (s) (p = 0.0024/0.0005; Reader 1/Reader2). High correlation coefficients regarding the number of bleeding sites (r = 0.9163/0.7692) in contrast to the number of involved vascular territories (r = 0.2888/0.0105) were observed for CTA in comparison to clinical gold-standard. In this context, CBCT demonstrated a very strong correlation for both parameters, the number of bleeding vessels (r = 0.9720/0.9721) and the number involved vascular territories (r = 0.9441/0.9441).

CONCLUSION

In complex cases of suspected haemorrhage, CBCT images can aid the interventionalist in detecting bleeding sites as well as narrowing down the number of involved vascular territories and thereby identifying feeding arteries of the bleeding source. Advances in knowledge: (1) CBCT showed no improvement in image quality. However, in complex bleeding cases CBCT information might aid in treatment planning. (2) CBCT improves visualization of bleeding vessels and involved feeding arteries. (3) Particularly, less experienced interventionalists might benefit from the three-dimensional information gathered by CBCT.

Evaluation and management of lower gastrointestinal bleeding

Lower gastrointestinal bleeding (LGIB) is a common cause of presentation to the emergency department and hospital admissions. The incidence of LGIB increases with age and the most common etiologies are diverticulosis, angiodysplasia, malignancy and anorectal diseases. Foremost modality for evaluation and treatment of LGIB is colonosopy. Other diagnostic tools such as nuclear scintigraphy, computed tomography, angiography and capsule endoscopy are also frequently used in the workup of LGIB. Choice of treatment modality depends on the hemodynamic status of the patient, rate of bleeding, expertise and available resources. We present a comprehensive review of the evaluation and management of LGIB.