The role of imaging in gastrointestinal bleed

Comparison of diagnostic value of technetium 99m-labeled red blood cell computed single photon emission computed tomography/computed tomography (99mTc-RBC SPECT/CT) and contrast-enhanced multidetector computed tomography (MDCT) for small bowel bleeding: a retrospective study

Background

Although small bowel bleeding is relatively rare, it is a potentially fatal disease, and its diagnosis still faces challenges. Technetium 99m-labeled red blood cell computed single photon emission computed tomography/computed tomography (99mTc-RBC SPECT/CT) and contrast-enhanced multidetector computed tomography (MDCT) are common imaging methods for diagnosing small bowel bleeding, but there have been no studies comparing their diagnostic efficacy for this purpose. This study aims to compare the diagnostic value of 99mTc-RBC SPECT/CT and contrast-enhanced MDCT for small bowel bleeding.

Methods

A total of 44 patients (30 males and 14 females, median age of 64 years) definitively diagnosed with small bowel bleeding and 15 non-small bowel bleeding patients (8 males and 7 females, median age of 66 years) were consecutively included in this study. All patients underwent 99mTc-RBC SPECT/CT and contrast-enhanced MDCT examinations at Beijing Friendship Hospital of Capital Medical University between January 2020 to September 2023. The definitive diagnosis had been made through surgery or colonoscopy, or through patient history, patient management, and clinical follow-up. We collected clinical data of the participants. 99mTc-RBC SPECT/CT and contrast-enhanced MDCT were reviewed in a blinded fashion for accuracy of detection of active bleeding as well as the active small bowel bleeding location.

Results

Among the 59 patients, the accuracy, sensitivity, and specificity of 99mTc-RBC SPECT were 27.3%, 93.3%, and 92.3%; for 99mTc-RBC SPECT/CT they were 76.3%, 40.5%, and 93.3%; whereas for contrast-enhanced MDCT they were 45.8%, 27.3%, and 100%, respectively. The diagnostic accuracy of 99mTc-RBC SPECT/CT for jejunal and ileal bleeding was high, at 100% and 86.4%, respectively. Meanwhile, 99mTc-RBC SPECT/CT had a higher accuracy in diagnosing more causes of small bowel bleeding. In 59 patients, the combination of 99mTc-RBC SPECT/CT and contrast-enhanced MDCT accurately diagnosed small bowel bleeding and provided precise localization in 50 patients, resulting in the accuracy, sensitivity, and specificity of 84.7%, 79.5%, and 100.0%, respectively.

Conclusions

99mTc-RBC SPECT/CT has high diagnostic value in diagnosing small bowel bleeding and is superior to 99mTc-RBC SPECT and contrast-enhanced MDCT. The combination of 99mTc-RBC SPECT/CT and contrast-enhanced MDCT can further improve the diagnostic accuracy of diagnosis, and can accurately guide the diagnosis and treatment of small bowel bleeding.

Advances in Vascular Diagnostics using Magnetic Particle Imaging (MPI) for Blood Circulation Assessment

Rapid and accurate assessment of conditions characterized by altered blood flow, cardiac blood pooling, or internal bleeding is crucial for diagnosing and treating various clinical conditions. While widely used imaging modalities such as magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound offer unique diagnostic advantages, they fall short for specific indications due to limited penetration depth and prolonged acquisition times. Magnetic particle imaging (MPI), an emerging tracer-based technique, holds promise for blood circulation assessments, potentially overcoming existing limitations with reduction in background signals and high temporal and spatial resolution, below the millimeter scale. Successful imaging of blood pooling and impaired flow necessitates tracers with diverse circulation half-lives optimized for MPI signal generation. Recent MPI tracers show potential in imaging cardiovascular complications, vascular perforations, ischemia, and stroke. The impressive temporal resolution and penetration depth also position MPI as an excellent modality for real-time vessel perfusion imaging via functional MPI (fMPI). This review summarizes advancements in optimized MPI tracers for imaging blood circulation and analyzes the current state of pre-clinical applications. This work discusses perspectives on standardization required to transition MPI from a research endeavor to clinical implementation and explore additional clinical indications that may benefit from the unique capabilities of MPI.

Cross-sectional imaging after pancreatic surgery: The dialogue between the radiologist and the surgeon

Pancreatic surgery is nowadays considered one of the most complex surgical approaches and not unscathed from complications. After the surgical procedure, cross-sectional imaging is considered the non-invasive reference standard to detect early and late compilations, and consequently to address patients to the best management possible. Contras-enhanced computed tomography (CECT) should be considered the most important and useful imaging technique to evaluate the surgical site. Thanks to its speed, contrast, and spatial resolution, it can help reach the final diagnosis with high accuracy. On the other hand, magnetic resonance imaging (MRI) should be considered as a second-line imaging approach, especially for the evaluation of biliary findings and late complications. In both cases, the radiologist should be aware of protocols and what to look at, to create a robust dialogue with the surgeon and outline a fitted treatment for each patient.

Artificial Intelligence for Identification of Images with Active Bleeding in Mesenteric and Celiac Arteries Angiography

PURPOSE

The purpose of this study is to evaluate the efficacy of an artificial intelligence (AI) model designed to identify active bleeding in digital subtraction angiography images for upper gastrointestinal bleeding.

METHODS

Angiographic images were retrospectively collected from mesenteric and celiac artery embolization procedures performed between 2018 and 2022. This dataset included images showing both active bleeding and non-bleeding phases from the same patients. The images were labeled as normal versus images that contain active bleeding. A convolutional neural network was trained and validated to automatically classify the images. Algorithm performance was tested in terms of area under the curve, accuracy, sensitivity, specificity, F1 score, positive and negative predictive value.

RESULTS

The dataset included 587 pre-labeled images from 142 patients. Of these, 302 were labeled as normal angiogram and 285 as containing active bleeding. The model's performance on the validation cohort was area under the curve 85.0 ± 10.9% (standard deviation) and average classification accuracy 77.43 ± 4.9%. For Youden's index cutoff, sensitivity and specificity were 85.4 ± 9.4% and 81.2 ± 8.6%, respectively.

CONCLUSION

In this study, we explored the application of AI in mesenteric and celiac artery angiography for detecting active bleeding. The results of this study show the potential of an AI-based algorithm to accurately classify images with active bleeding. Further studies using a larger dataset are needed to improve accuracy and allow segmentation of the bleeding.

Extravasated contrast volumetric assessment on computed tomography angiography in gastrointestinal bleeding: A useful predictor of positive angiographic findings

BACKGROUND

Gastrointestinal bleeding (GIB) is a severe and potentially life-threatening condition, especially in cases of delayed treatment. Computed tomography angiography (CTA) plays a pivotal role in the early identification of upper and lower GIB and in the prompt treatment of the haemorrhage.

AIM

To determine whether a volumetric estimation of the extravasated contrast at CTA in GIB may be a predictor of subsequent positive angiographic findings.

METHODS

In this retrospective single-centre study, 35 patients (22 men; median age 69 years; range 16-92 years) admitted to our institution for active GIB detected at CTA and further submitted to catheter angiography between January 2018 and February 2022 were enrolled. Twenty-three (65.7%) patients underwent endoscopy before CTA. Bleeding volumetry was evaluated in both arterial and venous phases via a semi-automated dedicated software. Bleeding rate was obtained from volume change between the two phases and standardised for unit time. Patients were divided into two groups, according to the angiographic signs and their concordance with CTA.

RESULTS

Upper bleeding accounted for 42.9% and lower GIB for 57.1%. Mean haemoglobin value at the admission was 7.7 g/dL. A concordance between positive CTA and direct angiographic bleeding signs was found in 19 (54.3%) cases. Despite no significant differences in terms of bleeding volume in the arterial phase (0.55 mL vs 0.33 mL, P = 0.35), a statistically significant volume increase in the venous phase was identified in the group of patients with positive angiography (2.06 mL vs 0.9 mL, P = 0.02). In the latter patient group, a significant increase in bleeding rate was also detected (2.18 mL/min vs 0.19 mL/min, P = 0.02).

CONCLUSION

In GIB of any origin, extravasated contrast volumetric analysis at CTA could be a predictor of positive angiography and may help in avoiding further unnecessary procedures.

Variceal and Nonvariceal Upper Gastrointestinal Bleeding Refractory to Endoscopic Management: Indications and Role of Interventional Radiology

For over 60 years, diagnostic and interventional radiology have been heavily involved in the evaluation and treatment of patients presenting with gastrointestinal bleeding. For patients who present with upper GI bleeding and have a contraindication to endoscopy or have an unsuccessful attempt at endoscopy for identifying or controlling the bleeding, interventional radiology is often consulted for evaluation and consideration of catheter-based intervention.

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.

Incidental Bleeding Gastrointestinal Stromal Tumor Identified on 99m Tc-RBC Scintigraphy

ABSTRACT

Various pathologies could lead to occult gastrointestinal (GI) bleeding. Here we report the case of a 73-year-old woman who presented with hematochezia and syncope, and was found to have a large bleeding GI stromal tumor incidentally from 99m Tc-RBC scintigraphy. This study was done after negative workup with CT angiography, colonoscopy, and capsule endoscopy for the source of GI bleeding. Final pathology confirmed the mass being a low-grade GI stromal tumor after exploratory laparotomy.

Characterization of single- and multi-energy CT performance of an oral dark borosilicate contrast media using a clinical photon-counting-detector CT platform

BACKGROUND

The feasibility of oral dark contrast media is under exploration in abdominal computed tomography (CT) applications. One of the experimental contrast media in this class is dark borosilicate contrast media (DBCM), which has a CT attenuation lower than that of intra-abdominal fat.

PURPOSE

To evaluate the performances of DBCM using single- and multi-energy CT imaging on a clinical photon-counting-detector CT (PCD-CT).

METHODS

Five vials, three with iodinated contrast agent (5, 10, and 20 mg/mL; Omnipaque 350) and two with DBCM (6% and 12%; Nextrast, Inc.), and one solid-water rod (neutral contrast agent) were inserted into two multi-energy CT phantoms, and scanned on a clinical PCD-CT system (NAEOTOM Alpha) at 90, 120, 140, Sn100, and Sn140 kV (Sn: tin filter) in multi-energy mode. CARE keV IQ level was 180 (CTDIvol: 3.0 and 12.0 mGy for the small and large phantoms, respectively). Low-energy threshold images were reconstructed with a quantitative kernel (Qr40, iterative reconstruction strength 2) and slice thickness/increment of 2.0/2.0 mm. Virtual monoenergetic images (VMIs) were reconstructed from 40 to 140 keV at 10 keV increments. On all images, average CT numbers for each vial/rod were measured using circular region-of-interests and averaged over eight slices. The contrast-to-noise ratio (CNR) of iodine (5 mg/mL) against DBCM was calculated and plotted against tube potential and VMI energy level, and compared to the CNR of iodine against water. Similar analyses were performed on iodine maps and VNC images derived from the multi-energy scan at 120 kV.

RESULTS

With increasing kV or VMI keV, the negative HU of DBCM decreased only slightly, whereas the positive HU of iodine decreased across all contrast concentrations and phantom sizes. CT numbers for DBCM decreased from -178.5 ± 9.6 to -194.4 ± 6.3 HU (small phantom) and from -181.7 ± 15.7 to -192.1 ± 11.9 HU (large phantom) for DBCM-12% from 90 to Sn140 kV; on VMIs, the CT numbers for DBCM decreased minimally from -147.1 ± 15.7 to -185.1 ± 9.2 HU (small phantom) and -158.8 ± 28.6 to -188.9 ± 14.7 HU (large phantom) from 40 to 70 keV, but remained stable from 80 to 140 keV. The highest iodine CNR against DBCM in low-energy threshold images was seen at 90 or Sn140 kV for the small phantom, whereas all CNR values from low-energy threshold images for the large phantom were comparable. The CNR values of iodine against DBCM computed on VMIs were highest at 40 or 70 keV depending on iodine and DBCM concentrations. The CNR values of iodine against DBCM were consistently higher than iodine to water (up to 460% higher dependent on energy level). Further, the CNR of iodine compared to DBCM is less affected by VMI energy level than the identical comparison between iodine and water: CNR values at 140 keV were reduced by 46.6% (small phantom) or 42.6% (large phantom) compared to 40 keV; CNR values for iodine compared to water were reduced by 86.3% and 83.8% for similar phantom sizes, respectively. Compared to 70 keV VMI, the iodine CNR against DBCM was 13%-79% lower on iodine maps and VNC.

CONCLUSIONS

When evaluated at different tube potentials and VMI energy levels using a clinical PCD-CT system, DBCM showed consistently higher CNR compared to iodine versus water (a neutral contrast).

Practical Aspects of Upper Gastrointestinal Bleeding in Children

Upper gastrointestinal bleeding (UGB) in children is a potentially life-threatening condition that represents a challenge for pediatricians and pediatric surgeons. It is defined as bleeding from any location within the upper esophagus to the ligament of Treitz. UGB can have many causes that vary with age. The impact on the child is often proportional to the amount of blood lost. This can range from mild bleeding that is unlikely to cause hemodynamic instability, to massive bleeding that requires admission to the intensive care unit. Proper and prompt management are very important factors in reducing morbidity and mortality. This article aims to summarize current research regarding the diagnosis and treatment of UGB. Most of the data used in the literature published on this subject is extrapolated from adulthood.

Utility of dual energy CT angiography in the evaluation of acute non-variceal gastrointestinal hemorrhage: comparison with digital subtraction angiography

PURPOSE

To evaluate the utility of dual energy CT angiography (DECTA) in acute non-variceal gastrointestinal hemorrhage (ANVGIH) compared to digital subtraction angiography (DSA) as gold standard.

MATERIALS AND METHODS

111 Patients (mean age: 39.2 years; 94 males) of ANVGIH who underwent both DECTA and DSA between January 2016 and September 2021 were included. Virtual monochromatic (VM) images at 10 keV increments from 40 to 70 keV and blended (120kVp equivalent) images of arterial phase of DECTA were evaluated independently by two readers blinded to DSA information. Quantitative analysis included measurement of attenuation in the major arteries (abdominal aorta, celiac artery, superior mesenteric artery), suspected vascular lesion, and lesion feeding artery to calculate contrast-to-noise ratios (CNRs) and signal-to-noise ratios (SNRs). Qualitative analysis assessed the image quality of each data set using a 3-point Likert scale. Findings on DSA were evaluated by a third reader and both DECTA and DSA were compared.

RESULTS

On linear blended images, vascular lesion was identified by reader 1 in 88 (79.3%) and by reader 2 in 87 (78.4%) patients and DSA showed lesion in 92 (82.9%) patients. The sensitivity and specificity of blended images and VM images of DECTA for lesion detection were not significantly different from each other. The CNR and SNR of arteries, vascular lesion and feeding artery were significantly higher at 70 keV (p < 0.005) compared to blended and other VM images. Although subjective scores for image quality were higher for 60 keV images by both readers, the difference was not statistically significant (p = 0.3). The interobserver agreement was mostly good.

CONCLUSION

In the assessment of ANVGIH, the 60 keV and 70 keV VM images improved the image quality and contrast, respectively, but there was no increase in diagnostic accuracy of VM image datasets compared to linearly blended images. Hence, the diagnostic utility of DECTA in ANVGIH is still uncertain.

Magnetic Particle Imaging in Vascular Imaging, Immunotherapy, Cell Tracking, and Noninvasive Diagnosis

Magnetic particle imaging (MPI) is a new tracer-based imaging modality that is useful in diagnosing various pathophysiology related to the vascular system and for sensitive tracking of cytotherapies. MPI uses nonradioactive and easily assimilated nanometer-sized iron oxide particles as tracers. MPI images the nonlinear Langevin behavior of the iron oxide particles and has allowed for the sensitive detection of iron oxide-labeled therapeutic cells in the body. This review will provide an overview of MPI technology, the tracer, and its use in vascular imaging and cytotherapies using molecular targets.

The role of repeated imaging in detecting complications in the post-operative period following pancreaticoduodenectomy: Serial CT imaging post-pancreaticoduodenectomy

BACKGROUND

Post-pancreaticoduodenectomy haemorrhage is a potentially life-threatening complication. Delay in the detection and subsequent management of complications contribute significantly to post-operative mortality and morbidity associated with pancreaticoduodenectomy.

METHODS

All patients undergoing pancreaticoduodenectomy at an Australian-based tertiary referral center between 2017 and 2022 were reviewed retrospectively. We identified those patients who suffered a post-pancreaticoduodenectomy haemorrhage and further analysed those patients who had their post-pancreaticoduodenectomy haemorrhage identified on repeated CT imaging performed within 24 h of their previous CT scan.

RESULTS

A total of 232 pancreaticoduodenectomies were identified for analysis during the study period, of which 23 patients (9.9%) suffered a post-pancreaticoduodenectomy haemorrhage. We present four patients who had their post-pancreaticoduodenectomy haemorrhage identified on repeat CT scan in the setting of a recent (within 24 h) CT scan which showed no evidence of active haemorrhage or pseudoaneurysm formation. All patients received prompt and definitive endovascular management through stent insertion or coil embolization resulting in successful cessation of bleeding. Three patients made an uncomplicated recovery thereafter. Unfortunately, one patient died as a complication of the bleed despite early and definitive endovascular intervention.

CONCLUSION

Our study highlights the importance of having a low threshold for repeated CT imaging in the post-pancreaticoduodenectomy setting, particularly when there remains a high index of suspicion clinically for a post-operative complication, even in the context of previous benign imaging. Given the complexity of pancreaticoduodenectomy, we believe early detection with liberal imaging allows the best chance at successfully managing the morbidity and mortality associated in the post-pancreaticoduodenectomy setting.

The Role of CT-Angiography in the Acute Gastrointestinal Bleeding: A Pictorial Essay of Active and Obscure Findings

Gastrointestinal bleeding is a potentially life-threatening abdominal emergency that remains a common cause of hospitalisation. Although 80–85% of cases of gastrointestinal bleeding resolve spontaneously, it can result in massive haemorrhage and death. The presentation of gastrointestinal bleeding can range from asymptomatic or mildly ill patients requiring only conservative treatments to severely ill patients requiring immediate intervention. Identifying the source of the bleeding can be difficult due to the wide range of potential causes, the length of the gastrointestinal tract and the intermittent nature of the bleeding. The diagnostic and therapeutic approach is fully dependent on the nature of the bleeding and the patient’s haemodynamic status. Radiologists should be aware of the appropriate uses of computed tomography angiography and other imaging modalities in patients with acute gastrointestinal bleeding, as well as the semiotics of bleeding and diagnostic pitfalls in order to appropriately diagnose and manage these patients. The learning objective of this review is to illustrate the computed tomography angiography technique, including the potential role of dual-energy computed tomography angiography, also highlighting the tips and tricks to identify the most common and uncommon features of acute gastrointestinal bleeding and its obscure form.

Massive Gastrointestinal Bleeding Due to Jejunal Diverticula in a Community Hospital: A Case Report and Review of Diagnostic and Therapeutic Options

Small bowel diverticula are rare and often asymptomatic. Severe lower gastrointestinal bleeding from jejunal diverticula is rarely reported and, therefore, should be considered a differential diagnosis in all cases of lower gastrointestinal bleeding with nonconclusive gastroscopy and colonoscopy. In this case report, we discuss a case of a 75-year-old male with massive lower gastrointestinal bleeding from jejunal diverticula. Initial gastroscopy did not reveal the source of bleeding. Repeat upper endoscopy with a pediatric colonoscope identified jejunal diverticula as the likely source of bleeding. Angiography identified the site of extravasation, and successful angioembolization was done by interventional radiology.

Management of life-threatening hemoperitoneum with minimally invasive percutaneous superselective arterial embolization

The management of spontaneous hemoperitoneum centers on clinical suspicion, fluid resuscitation, appropriate early imaging, and therapeutic intervention. Traditionally, explorative laparotomy has been the treatment of choice for idiopathic spontaneous intraabdominal hemorrhage, but as less invasive percutaneous techniques have matured, superselective arterial embolization may play a critical role in emergent treatment. This case report describes a 65-year-old woman with large-volume hemoperitoneum. At angiography, a single pseudoaneurysm of the middle colic artery was identified and treated with superselective endovascular methods.

Acute Gastric Hemorrhage due to Gastric Cancer Eroding Into a Splenic Artery Pseudoaneurysm: Two Dangerously Rare Etiologies of Upper Gastrointestinal Bleeding

Splenic artery pseudoaneurysms (SAPs) are rare causes of upper gastrointestinal bleeding (UGIB), with less than 250 reported cases in the literature. The highest incidence of SAPs is in patients with a history of acute or chronic pancreatitis or splenic artery trauma. SAP in the setting of gastric malignancy is an exceedingly rare finding. We present the unusual hospital course of an 82-year-old male with advanced gastric cancer presenting with UGIB secondary to a visceral communication between his known gastric malignancy and a SAP.