CT结肠成像对有临床症状的结直肠癌病人的排除诊断

目的 CT结肠成像技术已经越来越多地用于有结直肠症状病人的影像学评价。本研究的目的是评价CT结肠成像技术对有临床症状的老年病人在排除结直肠癌的诊断中的作用。方法对2002年3月—2007年12月间进行CT结肠成像的1359例病人进行回顾性分析。金标准是一年内的内镜检查结果和(或)至数据分析时临床、内镜及影像学检     

Miss rate of colorectal cancer at CT colonography in average-risk symptomatic patients

Objectives

Computed tomographic colonography (CTC) is a less burdensome alternative to colonoscopy in excluding colorectal cancer (CRC) in symptomatic patients. We evaluated the proportion of patients who underwent CTC in whom CRC was missed.

Methods

Patients who had undergone CTC in the period 1 January 2007 to 1 January 2011 were merged with all cases of CRC recorded in the Cancer Registry between 1 January 2007 and 1 July 2011 to identify all patients who had undergone CTC less than 2 years before CRC had been diagnosed.

Results

In 53 out of 1,855 patients who had undergone CTC, CRC was diagnosed. Of these, 40 patients had suspected CRC and 5 had large polyps at CTC. In five patients with an indeterminate mass, further investigation confirmed malignancy. One cancer in the caecum was missed because of poor distension. Two cancers were missed: one in the distal rectum and one in the ascending colon. Sensitivity of CTC for CRC was 94.3 % (95 % CI 88–100 %). The true miss rate, excluding the inadequate distended study, was 2 out of 53 (3.8 %).

Conclusion

This study shows that the miss rate for CTC is low, which means that CTC is accurate in excluding CRC in symptomatic patients at a relatively low risk of CRC.

Key Points

? The miss rate for colorectal cancer (CRC) on CT colonography (CTC) is low. ? CTC is accurate at excluding CRC in symptomatic patients. ? CTC is the method of choice in symptomatic patients to exclude CRC.     

Diagnostic accuracy and tolerability of contrast enhanced CT colonoscopy in symptomatic patients with increased risk for colorectal cancer

Objective

We compared the accuracy and tolerability of intravenous contrast enhanced spiral computed tomography colonography (CTC) and optical colonoscopy (OC) for the detection of colorectal neoplasia in symptomatic patients for colorectal neoplasia.

Methods

A prospective study was performed in 48 patients with symptomatic patients with increased risk for colorectal cancer. Spiral CTC was performed in supine and prone positions after colonic cleansing. The axial, 2D MPR and virtual endoluminal views were analyzed. Results of spiral CTC were compared with OC which was done within 15 days. The psychometric tolerance test was asked to be performed for both CTC and colonoscopy after the procedure.

Results

Ten lesions in 9 of 48 patients were found in CTC and confirmed with OC. Two masses and eight polyps, consisted of 1 tubulovillous, 1 tubular, 2 villous adenoma, 4 adenomatous polyp, 4 adenocarcinoma, were identified. Lesion prevalence was 21%. Sensitivity, specificity, accuracy, positive and negative predictive values were found 100%, 87%, 89%, 67% and 100%, respectively. Psychometric tolerance test showed that CTC significantly more comfortable comparing with OC (p = 0.00). CTC was the preferred method in 37% while OC was preferred in 6% of patients. In both techniques, the most unpleasant part was bowel cleansing.

Conclusion

Contrast enhanced CTC is a highly accurate method in detecting colorectal lesions. Since the technique was found to be more comfortable and less time consuming compare to OE, it may be preferable in management of symptomatic patients with increased risk for colorectal cancer.     

Colonography using multislice CT

Computed tomography (CT) represents the preferred imaging modality for imaging the large bowel when virtual endoscopic reconstructions are desired. Using the spiral acquisition technique, it has become possible to scan the entire abdomen within a single breathhold, however, slice thicknesses of 5 mm or more are necessary should the breathhold not last longer than 30-40 s. With the advent of multislice CT, contiguous 1-mm slices can be obtained through the entire abdomen while even shortening the breathhold to 25-30 s. The improved speed and spatial resolution of multislice CT results in remarkably sharp virtual reconstructions allowing detection of polyps with sizes less than 3 mm. The disadvantages must still be considered including a dataset consisting of up to 800 images representing a new challenge for postprocessing hard- and software.     

Coronary CT angiography in symptomatic patients

The currently best available spatial and temporal resolution for retrospectively ECG gated coronary multi-detector-row CT angiography is 0.4 mm and 165 ms, respectively. These acquisition parameters are already rather close to cardiac catheter. Studies so far compared non-invasive coronary CT and convention angiography for the detection of coronary artery stenoses. The most promising result reported by all authors was the high negative predictive value of the CTA. It now needs to be determined if CTA is a reliable tool to rule out coronary artery stenoses in a patient cohort with low likelihood of CAD, such as those with atypical chest pain or ambiguous stress test. CTA may furthermore establish as a rapid and widely available tool to detect vulnerable plaques or intracoronary thrombus in patients with acute coronary syndrome and unstable angina. In patients with chronic stable angina, tools that determine myocardial ischemia under stress such as SPECT and MRI are probably better suited to determine the relevance of coronary artery stenoses. In this particular cohort, by displaying the extent and morphology of coronary atherosclerosis, CTA may help to direct the therapy to either intervention or surgery.     

CT colonography for synchronous colorectal lesions in patients with colorectal cancer: initial experience

Aim

To assess accuracy of CT colonography (CTC) in identifying synchronous lesions in patients with colorectal carcinoma.

Methods

This study included 174 consecutive patients undergoing CTC as part of staging or primary investigation where a colorectal cancer was diagnosed between 2004 and 2007. Prone unenhanced and portal phase enhanced supine series with air or CO₂ distension were acquired using 4- or 16-slice CT (Toshiba) and read by 2D ± 3D formats. Synchronous lesions were classified according to American College of Radiology’s (ACR) polyp classification. Segmental gold standard was flexible sigmoidoscopy/colonoscopy within 1 year and/or histology of colonic resection supplemented by follow-up. Nine patients without gold standard were excluded. Sensitivity, specificity and accuracy were calculated on a per polyp, per patient and per segment basis and discrepancies analysed.

Results

Direct comparable data were available for 764/990 colonic segments from 165 patients. Of 41 (C2–C4) synchronous lesions on “gold standard”, 33 were correctly identified on virtual colonoscopy (VC), overall per polyp sensitivity was 80.5%, with detection rates of 20/24 C3 (83.3%) and 3/3 C4 (100%) with per patient and per segment specificity of 95.4% and 99.2%, respectively.

Conclusion

CTC is an accurate technique to assess for significant synchronous lesions in patients with colorectal cancer and is applicable for total pre-operative colonic visualisation.     

Appearances of screen-detected versus symptomatic colorectal cancers at CT colonography

Objectives

The aim of this study was to compare the morphology, radiological stage, conspicuity, and computer-assisted detection (CAD) characteristics of colorectal cancers (CRC) detected by computed tomographic colonography (CTC) in screening and symptomatic populations.

Methods

Two radiologists independently analyzed CTC images from 133 patients diagnosed with CRC in (a) two randomized trials of symptomatic patients (35 patients with 36 tumours) and (b) a screening program using fecal occult blood testing (FOBt; 98 patients with 100 tumours), measuring tumour length, volume, morphology, radiological stage, and subjective conspicuity. A commercial CAD package was applied to both datasets. We compared CTC characteristics between screening and symptomatic populations with multivariable regression.

Results

Screen-detected CRC were significantly smaller (mean 3.0 vs 4.3 cm, p?<?0.001), of lower volume (median 9.1 vs 23.2 cm³, p?<?0.001) and more frequently polypoid (34/100, 34 % vs. 5/36, 13.9 %, p?=?0.02) than symptomatic CRC. They were of earlier stage than symptomatic tumours (OR?=?0.17, 95 %CI 0.07-0.41, p?<?0.001), and were judged as significantly less conspicuous (mean conspicuity 54.1/100 vs. 72.8/100, p?<?0.001). CAD detection was significantly lower for screen-detected (77.4 %; 95 %CI 67.9-84.7 %) than symptomatic CRC (96.9 %; 95 %CI 83.8-99.4 %, p?=?0.02).

Conclusions

Screen-detected CRC are significantly smaller, more frequently polypoid, subjectively less conspicuous, and less likely to be identified by CAD than those in symptomatic patients.

Key Points

? Screen-detected colorectal cancers (CRC) are significantly smaller than symptomatic CRC. ? Screening cases are significantly less conspicuous to radiologists than symptomatic tumours. ? Screen-detected CRC have different morphology compared to symptomatic tumours (more polypoid, fewer annular). ? A commercial computer-aided detection (CAD) system was significantly less likely to note screen-detected CRC.

     

结肠造影CT扫描对大肠肿瘤性病变的应用评价

目的 评价口服大剂量甘露醇螺旋CT结肠造影(spiral CT colonography, SCTC)对大肠肿瘤性病变的诊断价值.方法 27例志愿者及68例疑有结、直肠病变患者每人口服约1500 ml等渗甘露醇后,肌注20 mg山莨菪碱注射液,随后行螺旋CT三期扫描,并在工作站上进行多平面重建、最大密度投影, 对正常组大肠进行准确分区,测量各区肠壁厚度、大肠管径和肠壁强化程度,并与病变肠管进行对照,对其结果进行统计学处理.根据肠道准备效果将SCTC分为3级.对手术病理证实的61例大肠肿瘤性病变进行回顾分析.结果 所有受试者都成功完成了SCTC检查,其中1级52例,占54.7%, 2级39例,占41.1%,3级4例,占4.2%,总满意度为95.8%.61例病人中有60例清晰显示病变,其中结直肠癌30例,淋巴瘤8例,脓肿8例 ,结肠息肉8例,转移瘤4例,盲肠类癌3例.1例＜5 mm结肠息肉SCTC未检出.SCTC对病变的敏感度为98.36%,特异度为76.9%.30例大肠癌SCTC正确分期27例,Duke分期的准确性为90%(27/30).结论 SCTC是一种简便、易行、经济实惠,能全方位、多维显示大肠肿瘤性病变的方法.     

多种技术结合优化CT结肠造影后处理程序

目的 评价CT结肠造影(CTC)后处理方法对结肠病变检出的有效性,并总结了结肠CTC检查后处理的最优化程序.方法 分别应用多平面重建、表面重建、透明重建、仿真内窥镜和管腔展开等后处理方法,对42例经电子结肠镜或手术病理证实的结肠病变患者的结肠充气CTC数据进行分析.结果 42例患者共检出22枚息肉,28例结肠癌(2例肠壁局限性增厚,26例共28个肿块)和8例结肠炎性病变.对3种类型病变的检出率,多平面重建分别为81.8%、100%和100%;仿真内窥镜分别为100%、100%和87.5%;表面重建分别为36.4%、92.9%和62.5%;透明重建分别为45.5%、92.9%和62.5%.管腔展开技术对所检病变的显示率达100%.结论 采用优化程序对CTC数据进行后处理并结合多种后处理技术可提高CTC的诊断效率和准确率.     

TSH alone is not sufficient to exclude all patients with a functioning thyroid nodule from undergoing testing to exclude thyroid cancer

PURPOSE: The purpose of the study was to analyze whether the thyroid-stimulating hormone (TSH) alone avoids tests to exclude malignancy in all patients with functional thyroid nodules (FTN). METHODS: Sixty-nine patients with FTN on (99m)Tc scintigraphy, radioiodine uptake test (RIU), (99m)Tc thyroid uptake, TSH assay, T3, and T4 obtained within 48 h were retrospectively identified out of 2,356 thyroid scans performed from January 2000 to April 2007. FTNs were classified as causing total, partial, or no inhibition of the thyroid as group 1, 2, or 3, respectively. RESULTS: TSH was subnormal in 21 of 69 (30.43%) patients. In group 1 (N = 23, 33.3%), TSH was subnormal, normal, and high in eight, nine, and six patients; in group 2 (N = 17, 24.6%), TSH was subnormal, normal, and high in four, six, and seven patients, and in group 3 (N = 29, 42%), TSH was subnormal, normal, and high in 9, 13, and 7 patients, respectively. TSH was significantly lower in group 1. In T3, T4, (99m)Tc thyroid uptake, and RIU, there were no differences between the three groups. CONCLUSIONS: Only 30.43% of patients had subnormal TSH. TSH alone cannot avoid tests to exclude malignancy in all patients with FTN. FTN existence can only be accurately assessed by thyroid scintigraphy. The current incidence of FTN may be unknown because scintigraphy is not routinely performed in all patients with thyroid nodules. Thyroid scintigraphy of patients with high TSH can detect diseases such as Hashimoto's thyroiditis and identify patients with FTN in whom no further diagnostic procedures would be needed in patients with normal TSH levels with nondiagnostic fine-needle aspiration results.     

Perfusion CT imaging of colorectal cancer

Imaging plays an important role in the assessment of colorectal cancer, including diagnosis, staging, selection of treatment, assessment of treatment response, surveillance and investigation of suspected disease relapse. Anatomical imaging remains the mainstay for size measurement and structural evaluation; however, functional imaging techniques may provide additional insights into the tumour microenvironment. With dynamic contrast-enhanced CT techniques, iodinated contrast agent kinetics may inform on regional tumour perfusion, shunting and microvascular function and provide a surrogate measure of tumour hypoxia and angiogenesis. In colorectal cancer, this may be relevant for clinical practice in terms of tumour phenotyping, prognostication, selection of individualized treatment and therapy response assessment.Colorectal cancer is one of the commonest of cancers, accounting for 10% of all cancers, with approximately 1.2 million new cases each year. Colorectal cancer remains a major cause of morbidity and mortality worldwide, with approximately 609 000 deaths per annum.¹ Since a radical abdominopelvic resection approach for rectal cancer was described in 1908,² significant inroads have been made into its treatment, including surgery, radiotherapy and chemotherapy, which have all improved morbidity and local recurrence rates, and also had some impact on the overall survival rate. These have included the introduction of surgical techniques such as total mesorectal excision,^3,4 neoadjuvant radiotherapy prior to surgery to reduce the risk of local recurrence and an increase in the likelihood of resectability,^5–7 as well as a more aggressive treatment of oligometastatic disease. Trialling of novel targeted therapies such as bevacizumab, a recombinant humanized monoclonal antibody against the vascular endothelial growth factor (VEGF), and the selective use of epidermal growth factor receptor inhibitors, such as cetuximab and panitumumab, have also led to improvements in outcome in the metastatic setting.^8–10 These approaches have had a “knock-on” effect on imaging, requiring more accurate delineation of locoregional tumour extent and distant spread, and on the development of more sophisticated methods of tumour profiling to direct therapy and for assessing the therapy response and efficacy of the particular agent.This article will highlight our current understanding of the molecular characterization of colorectal cancer, the architectural and physiological aspects of the vascular network in colorectal cancer, and discuss how dynamic contrast-enhanced CT (DCE-CT; perfusion CT), one of the increasing number of functional imaging techniques available in the clinic, may assist the management of colorectal cancer.