Kenichi Utano

Preoperative evaluation of colorectal cancer using CT colonography, MRI, and PET/CT

Imaging studies are a major component in the evaluation of patients for the screening, staging and surveillance of colorectal cancer. This review presents commonly encountered findings in the diagnosis and staging of patients with colorectal cancer using computed tomography (CT) colonography, magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT colonography. CT colonography provides important information for the preoperative assessment of T staging. Wall deformities are associated with muscular or subserosal invasion. Lymph node metastases from colorectal cancer often present with calcifications. CT is superior to detect calcified metastases. Three-dimensional CT to image the vascular anatomy facilitates laparoscopic surgery. T staging of rectal cancer by MRI is an established modality because MRI can diagnose rectal wall laminar structure. N staging in patients with colorectal cancer is still challenging using any imaging modality. MRI is more accurate than CT for the evaluation of liver metastases. PET/CT colonography is valuable in the evaluation of extra-colonic and hepatic disease. PET/CT colonography is useful for obstructing colorectal cancers that cannot be traversed colonoscopically. PET/CT colonography is able to localize synchronous colon cancers proximal to the obstruction precisely. However, there is no definite evidence to support the routine clinical use of PET/CT colonography.

Preoperative T Staging of Colorectal Cancer by CT Colonography

PurposeThis study was designed to estimate the accuracy of CT colonography for the assessment of T stage in colorectal cancer.MethodsCT colonograms obtained from 246 lesions were reviewed by 3 investigators. Intestinal wall deformity on shaded-surface display and rough appearance around the intestine were studied to assess their relations to T stage. Intestinal wall deformity was classified into arc type, trapezoid type, and apple-core type, defined as a trapezoidal wall deformity involving ≥50 percent of the circumference of the lumen.ResultsAs for intestinal wall deformity, the rate of arc type was higher in Tis/T1 than in T2 (74 percent: 17/23 vs. 24 percent: 8/34, P < 0.0001); the rate of trapezoid type was 17 percent (4/23) in Tis/T1, 59 percent (20/34) in T2, and 15 percent (28/189) in T3/T4 (Tis/T1 vs.T2, P < 0.0001; T2 vs. T3/T4, P < 0.0001); and the rate of apple-core type was lower in T2 than in T3/T4 (18 percent: 6/34 vs. 81 percent: 154/189, P < 0.0001). Arc type, trapezoid type, and apple-core type were primarily associated with T1, T2, and T3/T4, respectively. When these criteria were used, the overall accuracy for T stage was 79 percent. Rough appearance was specific for T3/T4, but insensitive.ConclusionsCT colonography can provide important information for the preoperative assessment of T stage in colorectal cancer.

Gastrografin as an alternative booster to sodium phosphate in colon capsule endoscopy: safety and efficacy pilot study.

Background and study aims: Sodium phosphate is a key component of bowel preparation regimen for colon capsule endoscopy (CCE), but may cause serious complications. The aim of this study is to evaluate the use of Gastrografin, substituted for sodium phosphate, in CCE bowel preparation. Patients and methods: In total, 29 patients (median age 64 years; 23 females) underwent CCE, covered by the national health insurance system of Japan. All had a history of laparotomy and/or previously incomplete colonoscopy. On the day before examination, patients ingested 1 L of polyethylene glycol + ascorbic acid with 0.5 L of water in the evening, and again the same laxative on the morning of examination. After capsule ingestion, 50 mL of Gastrografin diluted with 0.9 L of magnesium citrate was administered, and then repeated after 1 hour. Results: The capsule excretion rate was 97 % (28/29). The median colon transit time was 2 hours 45 minutes and rapid transit (< 40 minutes) through the colon occurred in one patient (3.4 %). Bowel cleansing level was adequate in 90 % of patients. The polyp (≥ 6 mm) detection rate was 52 %. Diluted Gastrografin was well tolerated by patients. No adverse events occurred. Conclusion: Gastrografin can be an alternative to sodium phosphate in CCE bowel preparation regimen.

Diagnostic Performance and Patient Acceptance of Reduced-Laxative CT Colonography for the Detection of Polypoid and Non-Polypoid Neoplasms: A Multicenter Prospective Trial

Purpose To evaluate the diagnostic accuracy and patient acceptance of reduced-laxative computed tomographic (CT) colonography without computer-aided detection (CAD) for the detection of colorectal polypoid and non-polypoid neoplasms in a population with a positive recent fecal immunochemical test (FIT). Materials and Methods Institutional review board approval and written informed consent were obtained. This multicenter prospective trial enrolled patients who had positive FIT results. Reduced-laxative CT colonography and colonoscopy were performed on the same day. Patients received 380 mL polyethylene glycol solution, 20 mL iodinated oral contrast agent, and two doses of 20 mg mosapride the day before CT colonography. The main outcome measures were the accuracy of CT colonography for the detection of neoplasms 6 mm or larger in per-patient and per-lesion analyses and a survey of patient perceptions regarding the preparation and examination. The Clopper-Pearson method was used for assessing the 95% confidence intervals of per-patient and per-lesion accuracy. Survey scores were analyzed by using the Wilcoxon and χ2 tests. Results Three hundred four patients underwent both CT colonography and colonoscopy. Per-patient sensitivity, specificity, positive predictive value, and negative predictive value of CT colonography for detecting neoplasms 10 mm or larger were 0.91 (40 of 44), 0.99 (255 of 258), 0.93 (40 of 43), and 0.98 (255 of 259), respectively; these values for neoplasms 6 mm or larger were 0.90 (71 of 79), 0.93 (207 of 223), 0.82 (71 of 87), and 0.96 (207 of 215), respectively. Per-lesion sensitivities for detection of polypoid and non-polypoid neoplasms 10 mm or larger were 0.95 (40 of 42) and 0.67 (six of nine), respectively; those for neoplasms 6 mm or larger were 0.90 (104 of 115) and 0.38 (eight of 21), respectively (P < .05 for both). Patient acceptance of preparation and examination with CT colonography was significantly higher than that with colonoscopy, and 62% (176 of 282) of patients would choose CT colonography as the first examination if they have a positive FIT result in the future. Conclusion Reduced-laxative CT colonography without CAD is accurate in the detection of polypoid neoplasms 6 mm or larger but is less accurate in the detection of non-polypoid neoplasms. Reduced-laxative CT colonography has high patient acceptance and is an efficient triage examination for patients with a positive FIT.

Laterally spreading tumors: Limitations of computed tomography colonography

AIM To prospectively investigate the detection rate of laterally spreading tumors (LSTs) of the colorectum by computed tomography (CT) colonography (CTC). METHODS Patients with LSTs measuring ≥ 20 mm detected during colonoscopy were prospectively enrolled in the study. All patients underwent colonoscopy and subsequent CTC on the same day. CTC was performed using multi-detector CT without contrast in the prone and supine positions. Two radiologists blinded to the existence of LSTs read the virtual endoscopic images as well as 2-D images. LSTs were classified into granular and non-granular types based on colonoscopic appearance. RESULTS Forty-seven pathologically proven LSTs were evaluated prospectively. Histology included adenomas in 19, mucosal cancers in 19 and T1 cancers in 9. The mean diameter of the LSTs was 35.1 mm. Twenty-eight (60%) LSTs were correctly identified by CTC, and the configuration was similar to the colonoscopic appearance in most cases. Detection rate for the granular type was significantly higher than that for the non-granular type (71% vs 31%, P = 0.013). Detection rate of adenomas was significantly lower than mucosal cancers (32% vs 79%, P = 0.008) and T1 cancers (32% vs 78%, P = 0.042). CONCLUSION The detection rate of LSTs by CTC, particularly the non-granular type was not acceptable. Practitioners should be aware of the relatively low detection rate when using CTC.

Reversed intestinal malrotation with concurrent cecal carcinoma.

A 57‐year‐old man was admitted with a type 2 (ulcerated with clear margin) cancer in the cecum. Contrast‐enhanced CT showed that the superior mesenteric vein was anterior to the superior mesenteric artery, and the patient was suspected of having intestinal malrotation. A laparoscopic‐assisted ileocecal resection was performed. At operation, the cecum and the transverse colon passed through the root of the mesentery behind the superior mesenteric artery with the duodenum. Therefore, this was thought to be a reversed‐type intestinal malrotation. After the operation, 3D‐CT colonography with duodenography images were reconstructed to retrospectively confirm the diagnosis of a reversed malrotation. These images clearly demonstrated the abnormal anatomy and overall orientation of the intestine. Patients with a reversed intestinal malrotation and concurrent cecal cancer are extremely rare. Herein, we present a patient who underwent a laparoscopic‐assisted ileocecal resection for cecal cancer that presented concurrently with a reversed intestinal malrotation.

Accuracy of CT Colonography for Detection of Polypoid and Nonpolypoid Neoplasia by Gastroenterologists and Radiologists: A Nationwide Multicenter Study in Japan.

OBJECTIVES:The objective of this study was to assess prospectively the diagnostic accuracy of computer-assisted computed tomographic colonography (CTC) in the detection of polypoid (pedunculated or sessile) and nonpolypoid neoplasms and compare the accuracy between gastroenterologists and radiologists.METHODS:This nationwide multicenter prospective controlled trial recruited 1,257 participants with average or high risk of colorectal cancer at 14 Japanese institutions. Participants had CTC and colonoscopy on the same day. CTC images were interpreted independently by trained gastroenterologists and radiologists. The main outcome was the accuracy of CTC in the detection of neoplasms ≥6 mm in diameter, with colonoscopy results as the reference standard. Detection sensitivities of polypoid vs. nonpolypoid lesions were also evaluated.RESULTS:Of the 1,257 participants, 1,177 were included in the final analysis: 42 (3.6%) were at average risk of colorectal cancer, 456 (38.7%) were at elevated risk, and 679 (57.7%) had recent positive immunochemical fecal occult blood tests. The overall per-participant sensitivity, specificity, and positive and negative predictive values for neoplasms ≥6 mm in diameter were 0.90, 0.93, 0.83, and 0.96, respectively, among gastroenterologists and 0.86, 0.90, 0.76, and 0.95 among radiologists (P<0.05 for gastroenterologists vs. radiologists). The sensitivity and specificity for neoplasms ≥10 mm in diameter were 0.93 and 0.99 among gastroenterologists and 0.91 and 0.98 among radiologists (not significant for gastroenterologists vs. radiologists). The CTC interpretation time by radiologists was shorter than that by gastroenterologists (9.97 vs. 15.8 min, P<0.05). Sensitivities for pedunculated and sessile lesions exceeded those for flat elevated lesions ≥10 mm in diameter in both groups (gastroenterologists 0.95, 0.92, and 0.68; radiologists: 0.94, 0.87, and 0.61; P<0.05 for polypoid vs. nonpolypoid), although not significant (P>0.05) for gastroenterologists vs. radiologists.CONCLUSIONS:CTC interpretation by gastroenterologists and radiologists was accurate for detection of polypoid neoplasms, but less so for nonpolypoid neoplasms. Gastroenterologists had a higher accuracy in the detection of neoplasms ≥6 mm than did radiologists, although their interpretation time was longer than that of radiologists.

Double‐balloon colonoscopy carried out by a trainee after incomplete conventional colonoscopy

It has been reported that double‐balloon colonoscopy (DBC) is useful for patients after failed colonoscopy. In most cases previously reported, expert colonoscopists have carried out DBC. However, DBC may not require significant expertise. The objective of the present study is to assess DBC carried out by an inexperienced colonoscopist in patients referred after previously incomplete colonoscopy.

Virtual enteroscopy using air as the contrast material: a preliminary feasibility study.

Background:  There are no studies to date using air as an enteral contrast medium for small bowel expansion in virtual enteroscopy. We examine the feasibility of air as an enteral contrast medium for virtual enteroscopy to achieve small bowel expansion.

Blue laser imaging endoscopy system for the early detection and characterization of colorectal lesions: a guide for the endoscopist

Blue laser imaging is a new system for image-enhanced endoscopy using laser light. Blue laser imaging utilizes two monochromatic lasers (410 and 450 nm) instead of xenon light. A 410 nm laser visualizes vascular microarchitecture, similar to narrow band imaging, and a 450 nm laser provides white light by excitation. According to three recently published reports, the diagnostic ability of polyp characterization using blue laser imaging compares favorably with narrow band imaging. No published data are available to date regarding polyp detection with blue laser imaging. However, blue laser imaging has the possibility to increase the detection of colorectal polyps by depicting brighter and clearer endoscopic images, even at a distant view, compared with first-generation image-enhanced endoscopy. A clinical trial to compare the detection between blue laser imaging and xenon light is warranted.