Computed tomography colonography in 2014: An update on technique and indications

A Review on Emerging Techniques for Diagnosis of Colorectal Cancer

Common detection methods in practice for diagnosing colorectal cancer (CRC) are painful and invasive leading to less participation of individuals for CRC diagnosis. Whereas, improved or enhanced imaging systems and other minimally invasive techniques with shorter detection times deliver greater detail and less discomfort in individuals. Thus, this review is a summary of the diagnostic tests, ranging from the simple potential use in developing a flexible CRC treatment to the patient's potential benefits in receiving less invasive procedures and the advanced treatments that might provide a better assessment for the diagnosis of CRC and reduce the mortality related to CRC.

Caecal perforation from CT colonography: an unexpected complication

Computer tomography colonography (CTC) is an increasingly utilized diagnostic modality in Australia. CTC aims to image the entire colon, and is often used in higher risk patient populations. Colonic perforation following CTC is a rare complication, with only 0.008% of patients undergoing CTC requiring surgical intervention. Most published cases of perforation following CTC are due to identifiable causes, often involving the left colon or rectum. We present a rare case of caecal perforation following CTC, requiring right hemicolectomy. This report highlights the need for high suspicion for CTC complications, despite their rarity, and the utility of diagnostic laparoscopy for diagnosis in atypical presentations.

When to Perform a Colonoscopy in Diverticular Disease and Why: A Personalized Approach

Colonoscopy is a crucial diagnostic tool in managing diverticular disease (DD). Diverticulosis can often be an unexpected diagnosis when colonoscopy is performed in asymptomatic subjects, generally for colorectal cancer screening, or it could reveal an endoscopic picture compatible with DD, including acute diverticulitis, in patients suffering from abdominal pain or rectal bleeding. However, alongside its role in the differential diagnosis of colonic diseases, particularly with colon cancer after an episode of acute diverticulitis or segmental colitis associated with diverticulosis, the most promising use of colonoscopy in patients with DD is represented by its prognostic role when the DICA (Diverticular Inflammation and Complication Assessment) classification is applied. Finally, colonoscopy plays a crucial role in managing diverticular bleeding, and it could sometimes be used to resolve other complications, particularly as a bridge to surgery. This article aims to summarize “when” to safely perform a colonoscopy in the different DD settings and “why”.

Efficacy of CO₂ Infusion for Preoperative Computed Tomographic Angiography with Computed Tomographic Colonography

BACKGROUND Computed tomographic colonography (CTC) is useful for patients for whom colonoscopy may be difficult to perform and is widely employed to examine the vasculature prior to colorectal cancer surgery. Computed tomographic angiography (CTA) was shown to be beneficial intraoperatively to manipulate blood vessels and prevent vascular injury. Three-dimensional (3D)-CTA combined with CTC (3D-CTA with CTC) is useful for preoperative evaluations of the anatomy of mesenteric vessels, colon, and lymph nodes. We observed that when the intestine was dilated with carbon dioxide (CO₂), the arteriovenous delineation was often more pronounced than without CO₂. To clarify the effects of gas injection with and without CO₂ on hemodynamics and vascular passage, we compared the effect of contrast for blood vessels. MATERIAL AND METHODS Thirty patients with resectable colorectal cancer who underwent a preoperative CT examination at our institution from January to October 2019 were study participants. Of these, 15 underwent 3D-CTA and 15 had 3D-CTA with CTC. Three board-certified radiologists independently and blindly evaluated 18 blood vessels. CT values for each blood vessel were measured on each image. RESULTS CT values for 3D-CTA with CTC were significantly higher with CO₂ than without CO₂. The quality of 3D-CTA with CTC images for visualization of blood vessels was also significantly greater than that of 3D-CTA, especially those of arterial and intramesenteric venous systems. CONCLUSIONS Based on the higher image quality and CT values obtained by 3D-CTA with CTC for vessels, compared with by 3D-CTA imaging, 3D-CTA with CTC imaging might be useful in evaluating colorectal cancers.

Other imaging techniques: Double-contrast barium enema, endoscopic ultrasonography, multidetector CT enema, and computed tomography colonoscopy

Double-contrast barium enema (DCBE), transrectal endoscopic ultrasonography (REU), multidetector computerized tomography enema (MDCT-e), and computed tomography colonoscopy (CTC) have been successfully used for the diagnosis of bowel endometriosis. DCBE provides a complete overview of the entire colon and allows detecting cecal nodules. The accuracy of DCBE is operator dependent and, thus, it may have low specificity. It does not allow identifying the cause of the mass effect. DCBE requires the administration of barium and exposure to radiation. REU precisely estimates the distance between the rectosigmoid nodule and the anal verge. However, it allows investigating only the distal part of rectosigmoid, it misses anterior pelvic lesions, and it has poor sensitivity for the diagnosis of endometriomas. MDCT-e is accurate and reproducible in diagnosing intestinal endometriosis and in assessing its characteristics: the largest diameter of the nodule, the distance between the distal part of the nodule and the anal verge, and depth of infiltration of endometriosis in the intestinal wall. MDCT-e requires the administration of iodinated contrast medium (CM) and the exposure to radiations. CTC has good performance in the diagnosis of rectosigmoid endometriosis. It allows estimating the degree of intestinal stenosis CTC, and the distance between the intestinal endometriotic nodule and the anal verge. It requires exposure to radiations, and it may require the administration of an iodinated CM.

MRI analysis of fecal volume and dryness: Validation study using an experimental oxycodone-induced constipation model

BACKGROUND

Opioids are known to affect gastrointestinal motility, but their effect on fluid absorption and secretion is poorly understood in humans.

PURPOSE

To investigate the effect of oxycodone on colonic fecal volume and stool dryness by using a novel MRI-based technique.

STUDY TYPE

Prospective, randomized, double-blinded, crossover study.

SUBJECTS

Twenty-five healthy male volunteers (median age: 24 years [range: 21-56]; mean body mass index [BMI]: 23.9 kg/m² [range: 22.9-25.0]) without known gastrointestinal disease.

FIELD STRENGTH/SEQUENCE

T₂ -weighted and two-point Dixon MRI scans of the abdomen at 1.5 T.

ASSESSMENT

Subjects were treated for 5 days with prolonged-release oxycodone or a placebo. Imaging was performed on the first and last study day in each period. Images of the colon were analyzed with semiautomatic k-means-based segmentation software. Regional colonic fecal volumes were quantified excluding gas volume and colon wall. Two-point Dixon and T₂ -weighted MRI signal intensity were assessed as a proxy of colonic stool dryness. Data were obtained in a previously reported study.

STATISTICAL TESTS

Intraclass correlation coefficients were used to test the reliability of measurements between days, while repeated measures mixed models were applied to test treatment effects.

RESULTS

After oxycodone treatment, total colonic fecal volume was significantly increased compared with placebo (mean change 100 mL vs. -13 mL; P = 0.001), with the largest increase (24%) observed in the ascending colon/cecum (P = 0.001). Dixon signal increased (less water in colon content) after oxycodone treatment compared with placebo (mean 0.09 vs. -0.02; P < 0.001). T₂ -weighted signal decreased (less water in colon content) after oxycodone treatment compared with placebo (mean -0.03 vs. 0.03; P = 0.002).

DATA CONCLUSION

The 5-day oxycodone treatment increased colonic fecal volume and increased stool dryness compared with placebo. This imaging-based method for noninvasive analysis of colon content has the potential to characterize gastrointestinal symptoms in general, such as in constipation.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:733-745.

Ultra-low dose CT colonography with automatic tube current modulation and sinogram-affirmed iterative reconstruction: Effects on radiation exposure and image quality

Objective

To assess the radiation dose and image quality of ultra‐low dose (ULD)‐CT colonography (CTC) obtained with the combined use of automatic tube current (mAs) modulation with a quality reference mAs of 25 and sinogram‐affirmed iterative reconstruction (SAFIRE), compared to low‐dose (LD) CTC acquired with a quality reference mAs of 55 and reconstructed with filtered back projection (FBP).

Methods

Eighty‐two patients underwent ULD‐CTC acquisition in prone position and LD‐CTC acquisition in supine position. Both ULD‐CTC and LD‐CTC protocols were compared in terms of radiation dose [weighted volume computed tomography dose index (CTDI_vol) and effective dose], image noise, image quality, and polyp detection.

Results

The mean effective dose of ULD‐CTC was significantly lower than that of LD‐CTC (0.98 and 2.69 mSv respectively, P < 0.0001) with an overall dose reduction of 63.2%. Image noise was comparable between ULD‐CTC and LD‐CTC (28.6 and 29.8 respectively, P = 0.09). There was no relevant difference when comparing image quality scores and polyp detection for both 2D and 3D images.

Conclusion

ULD‐CTC allows to significantly reduce the radiation dose without meaningful image quality degradation compared to LD‐CTC.

Probe-based three-dimensional confocal laser endomicroscopy of brain tumors: technical note

Background

Confocal laser endomicroscopy (CLE) is used during fluorescence-guided brain tumor surgery for intraoperative microscopy of tumor tissue with cellular resolution. CLE could augment and expedite intraoperative decision-making and potentially aid in diagnosis and removal of tumor tissue.

Objective

To describe an extension of CLE imaging modality that produces Z-stack images and three-dimensional (3D) pseudocolored volumetric images.

Materials and methods

Hand-held probe-based CLE was used to collect images from GL261-luc2 gliomas in C57BL/6 mice and from human brain tumor biopsies. The mice were injected with fluorescein sodium (FNa) before imaging. Patients received FNa intraoperatively, and biopsies were imaged immediately in the operating room. Some specimens were counterstained with acridine orange, acriflavine, or Hoechst and imaged on a benchtop confocal microscope. CLE images at various depths were acquired automatically, compiled, rendered into 3D volumes using Fiji software and reviewed by a neuropathologist and neurosurgeons.

Results

CLE imaging, Z-stack acquisition, and 3D image rendering were performed using 19 mouse gliomas and 31 human tumors, including meningiomas, gliomas, and pituitary adenomas. Volumetric images and Z-stacks provided additional information about fluorescence signal distribution, cytoarchitecture, and the course of abnormal vasculature.

Conclusion

3D and Z-stack CLE imaging is a unique new option for live intraoperative endomicroscopy of brain tumors. The 3D images afford an increased spatial understanding of tumor cellular architecture and visualization of related structures compared with two-dimensional images. Future application of specific fluorescent probes could benefit from this rapid in vivo imaging technology for interrogation of brain tumor tissue.

A critical appraisal of advances in the diagnosis of diverticular disease

Diverticulosis of the colon is a common condition, and about one-fourth of those people develop symptoms, which is called 'diverticular disease' (DD). Since there are still some concerns about the diagnosis of DD, the aim of this review was to analyze current and evolving advances in its diagnosis. Area covered: Analysis of clinical, radiology, laboratory, and endoscopic tools to pose a correct diagnosis of DD was performed according to current PubMed literature. Expert commentary: A combination of clinical characteristic of the abdominal pain and fecal calprotectin expression may help to differentiate between symptomatic uncomplicated diverticular disease and irritable bowel syndrome. Abdominal computerized tomography (CT) scan is still the gold standard in diagnosing acute diverticulitis and its complications. CT-colonography may be useful as a predicting tool on the outcome of the disease. Diverticular Inflammation and Complications Assessment (DICA) endoscopic classification shows a significant relationship between severity of DICA score inflammatory indexes, as well as with severity of abdominal pain. Moreover, it seems to be predictive of the outcome of the disease in terms of acute diverticulitis occurrence/recurrence and surgery occurrence. Finally, preliminary data found intestinal microbiota analysis is a promising tool in diagnosing and monitoring this disease.

Does Computed Tomography-Based Virtual Colonoscopy Improve the Accuracy of Preoperative Assessment Based on Magnetic Resonance Imaging in Women Managed for Colorectal Endometriosis?

STUDY OBJECTIVE

To evaluate whether combining computed tomography-based virtual colonoscopy (CTC) with magnetic resonance imaging (MRI) improves preoperative assessment of colorectal endometriosis.

DESIGN

Retrospective study using prospectively recorded data (Canadian Task Force classification II-2).

SETTING

University tertiary referral center.

PATIENTS

Seventy-one women treated for colorectal endometriosis managed between June 2015 and May 2016.

INTERVENTIONS

Patients included in our study underwent colorectal surgery for deep endometriosis infiltrating the rectum or the sigmoid colon and had preoperative assessment using MRI and CTC. To establish the correlation between preoperative and intraoperative findings, the concordance kappa index was used.

MEASUREMENTS AND MAIN RESULTS

Preoperative data provided by MRI, CTC, and a combination of both were compared with intraoperative findings. All 71 patients had a total of 105 endometriotic intestinal lesions intraoperatively confirmed. Some 71.2% of rectal nodules and 60.0% of sigmoid nodules infiltrated the muscularis propria of the intestinal wall, with most infiltrating between 25% and 50% of the rectal circumference; 73% of rectal nodules and 96% of sigmoid nodules led to varying degrees of stenosis. The concordance between intraoperative and preoperative findings concerning the presence of rectal nodules was high, at .88 when associating CTC with MRI, whereas each imaging technique taken individually provided lower concordance coefficients. In our study 80.3% of patients underwent the procedure that had been preoperatively planned.

CONCLUSION

Our study suggests that associating MRI with CTC leads to improved accuracy in preoperative assessment of colorectal endometriosis and in subsequent preoperative choice of surgical procedures on the digestive tract.

TC Rectal Pathology: Findings at CT-Colonography

OBJECTIVE

To review the spectrum of benign and malignant rectal diseases, their findings on CT colonography, and their management.

CONCLUSION

Although CT colonography is not the first choice for the study of rectal disease, it is indicated in cases where optical colonoscopy is contraindicated or cannot be completed. Rectal lesions can go undetected because this anatomic area is difficult to evaluate; for this reason, it is essential to ensure optimal preparation and distension, moderate balloon insufflation, and careful 2D and 3D navigation with knowledge of the spectrum of rectal disease and its CT colonography signs.

Clinically Occult Rectal Carcinoma Identified in a Case of Streptococcus bovis Endocarditis on Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: A Case Report and Review of Literature

Numerous studies over past four decades have implicated a strong association of Streptoccus bovis infection with colorectal carcinomas. Strong is this association that a screening colonoscopy for identifying malignancy is considered mandatory in patients whose blood/fecal cultures show growth of this particular pathogen. Here, we report an interesting case of a 61-year-old female patient who presented with pyrexia of unknown origin for 3 weeks. Positron emission tomography/computed tomography, in addition to helping diagnose mitral valve endocarditis, also identified a clinically occult T2N0 rectal carcinoma.

Computed tomographic colonography in the evaluation of a case of giant colonic diverticulum

The aim of this article was to present our experience with CT-colonography evaluation of a case of giant colonic diverticulum. Despite the high prevalence of diverticular disease in the Western world, giant colonic diverticula are rare entities, with fewer than 200 cases reported in literature.

Advanced imaging of colorectal cancer: From anatomy to molecular imaging

Imaging techniques play a key role in the management of patients with colorectal cancer. The introduction of new advanced anatomical, functional, and molecular imaging techniques may improve the assessment of diagnosis, prognosis, planning therapy, and assessment of response to treatment of these patients. Functional and molecular imaging techniques in clinical practice may allow the assessment of tumour-specific characteristics and tumour heterogeneity. This paper will review recent developments in imaging technologies and the evolving roles for these techniques in colorectal cancer.

TEACHING POINTS

• Imaging techniques play a key role in the management of patients with colorectal cancer. • Advanced imaging techniques improve the evaluation of these patients. • Functional and molecular imaging allows assessment of tumour hallmarks and tumour heterogeneity.

Diagnostic value of computed tomography colonography (CTC) after incomplete optical colonoscopy

INTRODUCTION

This study evaluated the role of computed tomography colonography (CTC) in patients who previously underwent incomplete optical colonoscopy (OC). We analyzed the impact of colonic lesions in intestinal segments not studied by OC and extracolonic findings in these patients.

METHODS

Between January 2014 and May 2015, 61 patients with a history of abdominal pain and incomplete OC examination were studied by CTC. CTCs were performed by 320-row CT scan in both the supine and the prone position, without intravenous administration of contrast medium. In all patients both colonic findings and extracolonic findings were evaluated.

RESULTS

Among the study group, 24 CTC examinations were negative for both colonic and extracolonic findings while 6 examinations revealed the presence of both colonic and extracolonic findings. In 24 patients CTC depicted colonic anomalies without extracolonic ones, while in 7 patients it showed extracolonic findings without colonic ones.

DISCUSSION

CTC is a noninvasive imaging technique with the advantages of high diagnostic performance, rapid data acquisition, minimal patient discomfort, lack of need for sedation, and virtually no recovery time. CTC accurately allows the evaluation of the nonvisualized part of the colon after incomplete OC and has the distinct advantage to detect clinically important extracolonic findings in patients with incomplete OC potentially explaining the patient's symptoms and conditioning their therapeutic management.

CONCLUSION

CTC accurately allows the assessment of both colonic and extracolonic pathologies representing a useful diagnostic tool in patients for whom complete OC is not achievable.

Computed tomography colonography for the practicing radiologist: A review of current recommendations on methodology and clinical indications

Colorectal cancer (CRC) represents one of the most relevant causes of morbidity and mortality in Western societies. CRC screening is actually based on faecal occult blood testing, and optical colonoscopy still remains the gold standard screening test for cancer detection. However, computed tomography colonography (CT colonography) constitutes a reliable, minimally-invasive method to rapidly and effectively evaluate the entire colon for clinically relevant lesions. Furthermore, even if the benefits of its employment in CRC mass screening have not fully established yet, CT colonography may represent a reasonable alternative screening test in patients who cannot undergo or refuse colonoscopy. Therefore, the purpose of our review is to illustrate the most updated recommendations on methodology and the current clinical indications of CT colonography, according to the data of the existing relevant literature.

Diagnostic imaging and radiation exposure in inflammatory bowel disease

Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn’s disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.

Short Occult Retractile Fibrous Scar Causing Exclusive Retrograde Stenosis of the Sigmoid Colon: An Incidental Diagnosis Nineteen Years After a Single Episode of Colonic Diverticulitis

We report a rare case of purely retrograde stenosing stricture of the sigmoid descending colonic junction fortuitously diagnosed during the waning of a failed virtual colonoscopy in a 69-year-old patient. The rather asymptomatic patient was addressed to investigate a positive fecal occult blood test. He had suffered a single acute colonic diverticulitis episode 19 years before. A contrast-enhanced abdominal CT and complementary focused abdominal ultrasound fully diagnosed a short curvilinear contrast-enhancing “scar-like” tissue infiltrating the posterior colonic wall and developing retractile adherences with the retroperitoneum of the left iliac fossa. The imaging features are presented with pathologic correlation.

Colorectal cancer diagnosis: Pitfalls and opportunities

Colorectal cancer (CRC) is a major health problem in the Western world. The diagnostic process is a challenge in all health systems for many reasons: There are often no specific symptoms; lower abdominal symptoms are very common and mostly related to non-neoplastic diseases, not CRC; diagnosis of CRC is mainly based on colonoscopy, an invasive procedure; and the resource for diagnosis is usually scarce. Furthermore, the available predictive models for CRC are based on the evaluation of symptoms, and their diagnostic accuracy is limited. Moreover, diagnosis is a complex process involving a sequence of events related to the patient, the initial consulting physician and the health system. Understanding this process is the first step in identifying avoidable factors and reducing the effects of diagnostic delay on the prognosis of CRC. In this article, we describe the predictive value of symptoms for CRC detection. We summarize the available evidence concerning the diagnostic process, as well as the factors implicated in its delay and the methods proposed to reduce it. We describe the different prioritization criteria and predictive models for CRC detection, specifically addressing the two-week wait referral guideline from the National Institute of Clinical Excellence in terms of efficacy, efficiency and diagnostic accuracy. Finally, we collected information on the usefulness of biomarkers, specifically the faecal immunochemical test, as non-invasive diagnostic tests for CRC detection in symptomatic patients.

Application of CT virtual endoscopy in diagnosis of colorectal diseases

Colorectal diseases are a group of common diseases. In recent years, extensive attention has been paid to the application of computed tomography virtual endoscopy (CTVE) in the diagnosis of colorectal diseases. Through the literature search, combined with the author's experience, we explore the technical principle, bowel preparation and inspection method of CTVE, making a summary of the value of CTVE in the diagnosis of colorectal diseases. CTVE can fully observe morphological characteristics of colorectal cancer, polyps, and inflammatory disease. CTVE can not only determine the lesion location, shape, and size, but also confirm the extent of invasion into the colorectal wall, surrounding tissue and distant metastasis. However, the main limitation is that the detected lesion cannot be biopsied or treated during CTVE. Therefore, CTVE is a new, rapid, convenient, safe, non-invasive, and effective method for colorectal examination, which can be used for screening of colorectal diseases.

Review article: the pathophysiology and medical management of diverticulosis and diverticular disease of the colon

BACKGROUND

The incidence of diverticulosis and diverticular disease of the colon, including diverticulitis, is increasing worldwide, and becoming a significant burden on national health systems. Treatment of patients with diverticulosis and DD is generally based on high-fibre diet and antibiotics, respectively. However, new pathophysiological knowledge suggests that further treatment may be useful.

AIM

To review the current treatment of diverticulosis and diverticular disease.

METHODS

A search of PubMed and Medline databases was performed to identify articles relevant to the management of diverticulosis and diverticular disease. Major international conferences were also reviewed.

RESULTS

Two randomised controlled trials (RCT) found the role of antibiotics in managing acute diverticulitis to be questionable, particularly in patients with no complicating comorbidities. One RCT found mesalazine to be effective in preventing acute diverticulitis in patients with symptomatic uncomplicated diverticular disease. The role of rifaximin or mesalazine in preventing diverticulitis recurrence, based on the results of 1 and 4 RCTs, respectively, remains unclear. RCTs found rifaximin and mesalazine to be effective in treating symptomatic uncomplicated diverticular disease. The use of probiotics in diverticular disease and in preventing acute diverticulitis occurrence/recurrence appears promising but unconclusive. Finally, the role of fibre in treating diverticulosis remains unclear.

CONCLUSIONS

Available evidence suggests that antibiotics have a role only in the treatment of complicated diverticulitis. It appears to be some evidence for a role for rifaximin and mesalazine in treating symptomatic uncomplicated diverticular disease. Finally, there is not currently adequate evidence to recommend any medical treatment for the prevention of diverticulitis recurrence.