Contrast-enhanced CT Colonography Research Articles

The prognostic significance of extramural venous invasion detected via contrast-enhanced computed tomography colonography in colon cancer.

167 Background: The precise effects of extramural venous invasion (EMVI) and Spiculation on colon cancer recurrence remain poorly understood. This study investigated the clinical significance of ctEMVI and ctSpiculation as diagnosed via preoperative contrast-enhanced CT colonography (CTC) using three-dimensional multiplanar reconstruction (3D MPR) images. Methods: Patients with stage I–Ⅲ colon cancer (T2 or deeper) diagnosed via CTC at the National Cancer Center Hospital in Japan between 2013 and 2018 were retrospectively evaluated for ctEMVI and ctSpiculation, diagnosed by two observers using 3D MPR images of slices 0.5 mm thick. The interobserver reliability was assessed with Cohen’s kappa statistic, and recurrence-free survival (RFS) was analyzed using Kaplan–Meier curves. Preoperative clinical factors were subjected to Cox regression analysis in relation to RFS. Results: Of 922 patients, 544 eligible cases were analyzed. There were 50 (9.2%) ctEMVI-positive cases and 494 (90.8%) ctEMVI-negative cases, along with 186 (34.2%) ctSpiculation-positive cases and 358 (65.8%) with negative findings. Kappa coefficients for ctEMVI and ctSpiculation were 0.830 and 0.718, respectively. Kaplan–Meier analysis and log-rank tests demonstrated lower RFS in ctEMVI- and ctSpiculation-positive cases (p<0.001). In multivariable analysis, ctT4 (HR 2.95, 95% CI 1.73–5.02) and ctEMVI (2.97, 1.81–4.87) were independent factors associated with RFS. When stratifying TNM stages based on ctEMVI status, in N(+) (i.e., Stage III), ctEMVI-positive group had worse prognoses than negative group (5-year RFS rates; 52.0% vs. 78.5%, p=0.003). Similarly, in N(–) (i.e., Stage I and II), T3N0EMVI(+) cases had significantly worse prognoses than T3N0EMVI(–) and Stage I cases (50.6% vs. 89.3% and 90.1%) and were comparable to the T4N0 group (50.6% vs. 46.7%, p=0.844). Conclusions: Both ctEMVI and ctSpiculation are associated with RFS. ctEMVI is an independent predictor of recurrence and may be valuable in combination with preoperative TNM staging to identify patients at high risk for recurrence. [Table: see text]

Prognostic impact of extramural venous invasion detected by contrast-enhanced CT colonography in colon cancer.

The impact of computed tomography (CT)-detected extramural venous invasion on the recurrence of colon cancer is not fully understood. The aim of this study was to investigate the clinical significance of extramural venous invasion diagnosed before surgery by contrast-enhanced CT colonography using three-dimensional multiplanar reconstruction images. Patients with colon cancer staged greater than or equal to T2 and/or stage I-III who underwent contrast-enhanced CT colonography between 2013 and 2018 at the National Cancer Center Hospital in Japan were retrospectively investigated for CT-detected extramural venous invasion. Inter-observer agreement for the detection of CT-detected extramural venous invasion was evaluated and Kaplan-Meier survival curves were plotted for recurrence-free survival using CT-TNM staging and CT-detected extramural venous invasion. Preoperative clinical variables were analysed using Cox regression for recurrence-free survival. Out of 922 eligible patients, 544 cases were analysed (50 (9.2 per cent) were diagnosed as positive for CT-detected extramural venous invasion and 494 (90.8 per cent) were diagnosed as negative for CT-detected extramural venous invasion). The inter-observer agreement for CT-detected extramural venous invasion had a κ coefficient of 0.830. The group positive for CT-detected extramural venous invasion had a median follow-up of 62.1 months, whereas the group negative for CT-detected extramural venous invasion had a median follow-up of 60.7 months. When CT-TNM stage was stratified according to CT-detected extramural venous invasion status, CT-T3 N(-)extramural venous invasion(+) had a poor prognosis compared with CT-T3 N(-)extramural venous invasion(-) and CT-stage I (5-year recurrence-free survival of 50.6 versus 89.3 and 90.1 per cent respectively; P < 0.001). In CT-stage III, the group positive for CT-detected extramural venous invasion also had a poor prognosis compared with the group negative for CT-detected extramural venous invasion (5-year recurrence-free survival of 52.0 versus 78.5 per cent respectively; P = 0.003). Multivariable analysis revealed that recurrence was associated with CT-T4 (HR 3.10, 95 per cent c.i. 1.85 to 5.20; P < 0.001) and CT-detected extramural venous invasion (HR 3.08, 95 per cent c.i. 1.90 to 5.00; P < 0.001). CT-detected extramural venous invasion was found to be an independent predictor of recurrence and could be used in combination with preoperative TNM staging to identify patients at high risk of recurrence.

Imaging Recommendations for Diagnosis, Staging, and Management of Small Bowel and Colorectal Malignancies

AbstractSmall bowel malignancies are rare, though colorectal cancers are common. This article reviews the current imaging recommendations for small bowel and colorectal malignancies. Contrast-enhanced computed tomography (CT) is the imaging modality of choice for diagnosis/staging/response evaluation/follow-up of the small bowel and colonic tumors. Magnetic resonance imaging of the pelvis with high-resolution T2-weighted images in sagittal, oblique axial, and coronal planes is the imaging modality of choice for staging/response evaluation of anorectal tumors. CT colonography may be utilized as a tumor screening modality, alternative to colonoscopy.

Feasibility of Simple Oral Preparation Contrast-Enhanced CT Colonography (SOP-CE-CTC) Using Mannitol as a Neutral Oral Contrast Agent

Abstract Purpose This article prospectively assesses the feasibility of simple oral preparation contrast-enhanced computed tomography colonography (SOP-CE-CTC) using a large volume of oral 3% mannitol for good colonic distension along with mural and mucosal fold visualization. Methods A total of 100 patients in whom contrast CT abdomen was requested, recruited as per selection criteria, were advised to take mild oral bowel preparation for two nights, prior to the investigation. Then, after fasting overnight, they were asked to consume 1,500 to 2,000 mL of 3% mannitol solution in about an hour. Thirty minutes after completing the ingestion of oral mannitol, intravenous contrast was injected and SOP-CE-CTC was acquired at 55 seconds. Distension of six segments of the colon was evaluated by assigning scores 1 to 4 for qualitative assessment; and measuring the maximum luminal diameter of the colon, for quantitative assessment. Colonic mucosal and mural visualization were evaluated subjectively. All observations were recorded by two reviewers (with varying levels of experience) independently. Results On qualitative analysis, the colon showed optimal distension (score 4) in 58 to 89% cases on SOP-CE-CTC. There was agreement between both the reviewers in 89 to 99% cases (weighted kappa 0.820–0.979; p &lt; 0.001). On quantitative analysis, the mean of the maximum colonic diameter ranged between 3.4 and 5.2 cm; and both the reviewers agreed in 89 to 97% cases (weighted kappa 0.777–0.967; p &lt; 0.001). Mural and mucosal fold visualization in the proximal four segments of the colon was excellent (in 90–98%) but in the rectum and sigmoid it was 45 and 66%, respectively; both the reviewers agreed in 100% cases (weighted kappa 1.0 and p &lt; 0.001). Conclusion Good colonic distension, mural, and mucosal fold visualization can be achieved on SOP-CE-CTC using 1,500 to 2,000 mL of 3% oral mannitol and mild oral bowel preparation agents.

Measurement of circumferential tumor extent of colorectal cancer on CT colonography: relation to clinicopathological features and patient prognosis after surgery.

To examine the relationship between circumferential tumor extent of colorectal cancer (CRC) on CT colonography (CTC) and clinicopathological features including patient prognosis after surgery. This retrospective study performed at our institution from January 2013 to December 2019 enrolled 195 consecutive patients (110 men, 85 women; mean age, 64.7years) with CRC evaluated by contrast-enhanced CTC before surgery. The circumferential tumor extent rate (CER) was measured by CTC in virtual colon dissection (VCD) mode to examine the relation between the CER and clinicopathological features and patient prognosis. CER had association with tumor invasion depth (T), nodal involvement (N), distant metastasis (M), and stage. The Kruskal-Wallis tests showed significant difference for T, N and the stage (p < 0.0001, p = 0.0021 and p < 0.0001) and Wilcoxon rank sum test showed significant difference for M (p = 0.0015). According to the log-rank test, there were no significant differences in OS or DFS between patients with high and low CER. Circumferential tumor extent was significantly correlated with TNM categories and stage of CRC, but not with patient prognosis after surgery.

EXTRACOLONIC FINDINGS-IDENTIFICATION AT LOW-DOSE CTC.

In contrast to optical colonoscopy, computed tomography colonography (CTC) has the ability to reveal pathology outside of the colon. While identification of colorectal lesions at CTC requires only limited radiation dose, the detection of abnormalities in extracolonic soft tissue requires more radiation. The purpose of this study was to investigate the influence of ultra-low-dose (ULD) CTC on the detection and characterisation of extracolonic findings. In a prospective study 49 patients with colorectal symptoms were examined with CTC adding a ULD series (mean effective dose 0.9 ± 0.4 mSv) to the normal unenhanced standard dose (SD) series (mean effective dose 3.6 ± 1.2 mSv). Five radiologists individually and blindly evaluated the ULD, followed by evaluation of the SD after ≥9 weeks (median 35 weeks). A ViewDEX-based examination protocol was used, including a confidence scale and a graded assessment of need for follow-up according to the CTC Reporting and Data System (C-RADS E0–E4). The reference findings comprised the combined information from CTC (ULD, SD and contrast-enhanced CTC series) and a 4-year radiological and clinical follow-up. For the overall detection of reference findings (E2–E4) we found a statistically significant difference in favour of SD. This, however, was not the case when looking at classification of possibly important/important reference findings (E3–E4). Our results suggest that CTC with ULD (0.9 mSv) is comparable to SD (3.6 mSv) for identification of clinically relevant extracolonic pathology, but there is a large inter-observer variability.

CT reconstruction with thick slices not only underestimates lymph node size but also reduces data reproducibility in colorectal cancer.

Reliable size measurement of lymph node (LN) metastases is important for the evaluation of cancer treatment. However, image analyses without proper settings may result in inappropriate diagnoses and staging. To investigate whether reconstruction slice thickness in computed tomography (CT) affects measurements of LN size and reproducibility. We analyzed 48 patients with histological diagnoses of sigmoid colon and rectal cancer who underwent contrast-enhanced CT colonography as part of a surgical treatment preparation. A board-certified radiologist selected 106 LNs whose short-axis diameter was ≥5 mm on 1-mm-thick images; the short-axis diameters were measured on 1- and 5-mm-thick images by the radiologist and residents and compared using Wilcoxon matched-pairs signed rank test. Data variation and reproducibility were evaluated using the F test and Bland-Altman analysis. P<0.05 was considered significant. Short-axis diameters measured on 5-mm-thick images were significantly lower than those measured on 1-mm-thick images (P<0.01), even in the LNs whose short-axis diameters were over twice the slice thickness (P<0.05). Of the 106 LNs, 57 showed short-axis diameter <5 mm on 5-mm-thick images; the maximum short-axis diameter was 6.7 mm on a 1-mm thick image. Data variation was significantly larger on 5-mm thick images than 1-mm-thick images in small LNs (P<0.05) and reproducibility on 5-mm-thick images was inferior to that on 1-mm-thick images. Thick reconstruction slices in CT can result in an underestimation of LN size and reduce data reproducibility. When measuring LN size, a thin reconstruction slice would be recommended based on targeted LN size.

Contrast-enhanced CT colonography for colorectal cancer localization in laparoscopic surgery

Contrast-enhanced CT colonography for colorectal cancer localization in laparoscopic surgery

Submilisievert ultralow-dose CT colonography using iterative reconstruction technique: a feasibility study.

Computed tomography (CT) colonography is a well established modality for the examination of symptomatic patients as well as in screening. Recent technical advances in improving image quality by iterative reconstruction contribute to the reduction of the radiation dose which is a major concern in CT imaging. To evaluate image quality of ultralow-dose submilisievert CT colonography using hybrid iterative reconstruction technique. Sixteen patients underwent contrast-enhanced CT colonography with standard protocol in supine position and ultralow-dose protocol in prone position. Ultralow-dose datasets were reconstructed with filtered back projection and an advanced hybrid iterative reconstruction technique. Two radiologists independently evaluated 96 colonic segments for image quality in the endoluminal view and axial thin sections. Colonic distension, smoothness of colonic wall and distortion of folds in the endoluminal view, sharpness of colonic wall delineation, perceived image noise, and presence of photon starvation artifact were rated on a five-point scale. Intraluminal noise expressed as standard deviation of Hounsfield density was measured in all segments. The mean radiation dose was 0.42 mSv and 5.48 mSv in prone and supine scans, respectively. All distended segments were rated evaluable in standard dose and ultralow-dose series reconstructed with the iterative reconstruction technique, whereas in 61% segments image quality was rated poor or unacceptable in ultralow-dose series where filtered back projection was used with worst ratings in the rectum and the sigmoid colon. This pilot study shows that iterative reconstruction technique is a feasible method to decrease the radiation dose from CT colonography for both positions below 1mSv. Further investigations of larger scale need to be done to clarify, whether such a low radiation dose would influence the detection of polyps.

Vascular Map Combined with CT Colonography for Evaluating Candidates for Laparoscopic Colorectal Surgery.

Contrast-enhanced computed tomography colonography (CE-CTC) is a useful guide for the laparoscopic surgeon to avoid incorrectly removing the colonic segment and the failure to diagnose of synchronous colonic and extra-colonic lesions. Lymph node dissection and vessel ligation under a laparoscopic approach can be time-consuming and can damage vessels and organs. Moreover, mesenteric vessels have extreme variations in terms of their courses and numbers. We describe the benefit of using an abdominal vascular map created by CE-CTC in laparoscopic colorectal surgery candidates. We describe patients with different diseases (colorectal cancer, diverticular disease, and inflammatory bowel disease) who underwent CE-CTC just prior to laparoscopic surgery.

Clinical indications for computed tomographic colonography: European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastrointestinal and Abdominal Radiology (ESGAR) Guideline.

This is an official guideline of the European Society of Gastrointestinal Endoscopy (ESGE) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR). It addresses the clinical indications for the use of computed tomographic colonography (CTC). A targeted literature search was performed to evaluate the evidence supporting the use of CTC. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was adopted to define the strength of recommendations and the quality of evidence. Main recommendations 1 ESGE/ESGAR recommend computed tomographic colonography (CTC) as the radiological examination of choice for the diagnosis of colorectal neoplasia. ESGE/ESGAR do not recommend barium enema in this setting (strong recommendation, high quality evidence). 2 ESGE/ESGAR recommend CTC, preferably the same or next day, if colonoscopy is incomplete. Delay of CTC should be considered following endoscopic resection. In the case of obstructing colorectal cancer, preoperative contrast-enhanced CTC may also allow location or staging of malignant lesions (strong recommendation, moderate quality evidence). 3 When endoscopy is contraindicated or not possible, ESGE/ESGAR recommend CTC as an acceptable and equally sensitive alternative for patients with symptoms suggestive of colorectal cancer (strong recommendation, high quality evidence). 4 ESGE/ESGAR recommend referral for endoscopic polypectomy in patients with at least one polyp ≥ 6 mm in diameter detected at CTC. CTC surveillance may be clinically considered if patients do not undergo polypectomy (strong recommendation, moderate quality evidence). 5 ESGE/ESGAR do not recommend CTC as a primary test for population screening or in individuals with a positive first-degree family history of colorectal cancer (CRC). However, it may be proposed as a CRC screening test on an individual basis providing the screenee is adequately informed about test characteristics, benefits, and risks (weak recommendation, moderate quality evidence).

Contrast-Enhanced CT Colonography Features of Rectal Carcinoid Tumors

Purpose: The purpose of this study was to retrospectively assess the detectability and enhancement pattern of rectal carcinoid tumors on contrast-enhanced computed tomography colonography (CE-CTC). Methods: The study sample consisted of 12 lesions in nine patients of rectal carcinoid tumors. To evaluate the detectability, two radiologists reviewed axial and 3D images including air enema (AE), virtual endoscopy (VE), and virtual colon dissection (VCD). To determine the contrast enhancement pattern of the tumors, the CT attenuation value of each lesion was measured in three phases. Results: Four of the 12 lesions (33%) were detected on axial images in patients in both the prone and supine positions, the sizes of which were 6 mm or larger. Seven lesions (58%), including the four lesions mentioned above, were detected on 3D images including AE and VE in patients in the prone position, the sizes of which were 5 mm or larger. The ranges of CT attenuation values of the lesions at 40 s, 70 s and 240 s were 112 - 147, 116 - 140 and 82 - 97 HU, respectively. Conclusion: Rectal carcinoid tumors are challenging to detect on CE-CTC. They demonstrated enhancement at the early phase and washout at the delayed phase on CE-CTC.

Role of preoperative CT colonography in patients with colorectal cancer.

In patients with colorectal cancer (CRC), accurate preoperative evaluation is essential for a correct therapeutic plan. Colonoscopy and intravenous contrast-enhanced computed tomography (CT) are currently recommended in the preoperative work-up for CRC. Preoperative colonoscopy has some limitations such as misdiagnosis of synchronous cancers in cases of incomplete exploration of the colon and inaccurate tumor localization. Intravenous contrast-enhanced CT successfully documents distant metastases although it sometimes enables unsatisfactory locoregional staging. Computed tomography colonography (CTC) is obtained after gas insufflation of the colon and offers a comprehensive preoperative evaluation in patients with CRC, including a definition of the segmental location of the tumor, presence of synchronous lesions or lack thereof, and fairly accurate locoregional staging. CTC has some limitations, including a lack of biopsy capability, suboptimal sensitivity for synchronous small polyps, and unsatisfactory nodal staging. Bearing in mind these limitations, CTC could be employed as a "one-stop-shop" examination for preoperative assessment in patients with CRC.

CT colonography in the diagnosis and management of colorectal cancer: Emphasis on pre- and post-surgical evaluation

This article addresses the use of computed tomographic colonography (CTC) for the diagnosis and management of colorectal cancer, focusing on presurgical evaluation of the colon proximal to an occlusive cancer and surveillance after cancer resection surgery. The key evidences accumulated in the literature and future work needed are summarized. CTC is a technically robust and the most practical method to evaluate the colon proximal to an occlusive cancer, which prevents colonoscopic examination past the occlusion, either before or after metallic stent placement. The high sensitivity of CTC for detecting cancers and advanced adenomas in the proximal colon can help prevent additional surgical procedures in patients showing negative results. However, the accuracy of CTC for distinguishing intramural cancers from adenomas is low, and the technique is limited in guiding management when a medium-sized lesion that do not show invasive features such as pericolic extension or nodal metastasis is found in the proximal colon. A maximal diameter ≥ 15 mm has been proposed as a criterion for surgical removal of proximal lesions. However, this needs to be verified in a larger cohort. In addition, the influence of presurgical CTC results on the current post-cancer resection colonic surveillance timeline remains to be determined. CTC can be readily added to the routine abdominopelvic CT in the form of contrast-enhanced CTC, which can serve as an effective stand-alone tool for post-cancer resection surveillance of both the colorectum and extracolonic organs. Although the accuracy of CTC has been demonstrated, its role in the current colonoscopy-based postoperative colonic surveillance protocols remains to be determined. Readers of CTC also need to be knowledgeable on the colonic lesions that are unique to the postoperative colon.

Impact of contrast-enhanced computed tomography colonography on laparoscopic surgical planning of colorectal cancer

To evaluate the impact of contrast-enhanced computed tomography colonography (CE-CTC) on laparoscopic surgery planning in patient with stenosing colorectal cancer. Sixty-nine patients with endoscopically proven colorectal cancer underwent CE-CTC, after incomplete conventional colonoscopy. Two experienced radiologists evaluated site, length, and TNM staging of colorectal cancers on three-dimensional double contrast enema-like views, 2D axial and multiplanar reconstructions. All the patients underwent colorectal resection and surgery bulletin, pathology of surgical specimens, and radiological follow-up at about 8 months were used as reference standard. The detection rate of colorectal cancer was 100 % (75/75); CE-CTC allowed for a diagnosis of a synchronous colorectal cancer in five patients (7 %). CE-CTC correctly judged the site of the lesions in all the cases; clinically significant localization errors at conventional colonoscopy were noted in 3 out of 69 patients (4 %). Additional colonic polyps greater than 6 mm in diameter were found in 21 out of 69 patients (30 %); in two patients (3 %) the surgeon performed an enlarged colectomy to include synchronous polyps proximal to colorectal cancer. Sensitivity, specificity, PPV, NPV, and accuracy were for T1-T2 vs. T3-T4: 96 %, 71 %, 92 %, 87 %, and 91 %, respectively; for N: 94 %, 42 %, 64 %, 86 %, and 70 %; for M: 100 %, 100 %, 83 %, 100 %, and 97 %. There were no complications associated with CE-CTC. Information given by CE-CTC concerning colorectal cancer location and synchronous colonic cancers and polyps changed the laparoscopic surgical strategy in almost 14 % of patients.

Contrast-Enhanced Computed Tomography Colonography in Preoperative Distinction between T1-T2 and T3-T4 Staging of Colon Cancer

To predict the T stage of nonrectal colon cancer using contrast-enhanced computed tomography colonography. Sixty-one patients with 67 nonrectal colon cancers consecutively underwent contrast-enhanced computed tomography colonography after an incomplete colonoscopy. Two readers evaluated wall deformity and perilesional fat abnormality on three-dimensional double contrast enema-like views and multiplanar reconstructions. Pathology was used as the standard of reference. McNemar, Fisher, and Cohen κ statistics were used. At pathologic examination, we found the following stages: T1 (n = 5), T2 (n = 10), T3 (n = 41), T4a (n = 6), and T4b (n = 5). Intraobserver and interobserver reproducibilities were almost perfect for wall deformity (κ = 1.00 and κ = 0.88, respectively), substantial for perilesional fat abnormality (κ = 0.79 and κ = 0.74, respectively). Using the results of the more experienced reader, accuracy of wall deformity ≥50% (apple-core) alone for T ≥ 3 was 62 of 67 (0.93, 95% confidence interval [CI] 0.83-0.97) and that of perilesional fat abnormality alone was 37 of 67 (0.55, 95% CI 0.43-0.67) (P < .001). Predictive value for ≥ T3 of the association wall deformity ≥50% with perilesional fat abnormality was 22 of 22 (1.00, 95% CI 0.85-1.00), higher, but not significantly, than that of wall deformity ≥50% with normal perilesional fat 29 of 33 (0.88, 95% CI 0.72-0.97) (P = .148, Fisher exact test). The presence of apple-core wall deformity, regardless of perilesional fat abnormality, is highly predictive of stage T3 or higher.

Computed tomography (CT) colonography with CT arteriography and venography for the workup of intestinal transplant candidates

Prior to intestinal transplantation, prospective candidates must undergo a series of radiologic examinations to address a variety of clinical issues. To date, little literature exists to guide physicians in this preoperative assessment. Multiple imaging studies can provide overlapping information. We have developed a simple two- or three-test protocol to streamline the workup. Sixteen adult patients presented as potential intestinal transplant candidates to Georgetown University Hospital. All but two patients underwent the full protocol of a biphasic IV contrast-enhanced computed tomography (CT) scan of the chest, abdomen, and pelvis with rectal carbon dioxide, an upper gastrointestinal study with small bowel follow through, and fistulogram when appropriate. Three-dimensional (3-D) reconstructions of the vascular anatomy as well as the colon were also generated. A telephone survey to other transplant centers was additionally conducted to compare radiographic evaluations. Overall, 15 of the 16 scans were diagnostic. One patient required a barium enema. Mean examinations per patient was 2.4. Only one of seven other centers was performing CT colonography in prospective intestinal transplant candidates. Our protocol provided all the necessary anatomic information needed to evaluate prospective transplant candidates. CT colonography with angiography is a suitable alternative to more time-consuming radiological studies.

The use of computed tomographic colonography in predicting the difficulty of endoscopic treatment for large protruding neoplasms

Dear Editor: Submucosal fibrosis is considered a major hurdle in endoscopic submucosal dissection (ESD), which is an effective technique for treating colorectal neoplasms. Although it is relatively easy to predict the difficulty of endoscopic resection for laterally spreading tumors (LST), it is more difficult in the case of large protruding lesions (Paris type 0-Is, >20 mm in diameter) such as villous tumors, which are often eventually removed by multiple piecemeal resection. However, considering the high incidence of recurrent or residual tumors and the difficulty of precise histopathological evaluation, piecemeal endoscopic mucosal resection (EMR) should be avoided. Instead, when endoscopic resection is predicted to be difficult, laparoscopic assisted colectomy is a viable treatment option; therefore, the objective evaluation of fibrotic changes in the submucosal layer is important. Although this evaluation may be accomplished using endoscopic miniprobe ultrasonography (mEUS), which is effective in assessing the depth of invasion in both gastric cancer and colorectal neoplasms as well as that of submucosal fibrosis for flat or depressed lesions, its limited depth of penetration is a disadvantage in assessing protruding lesions. Moreover, the observation of lesions located on the oral side of folds using mEUS is also considered difficult, and a different method may be more suitable for identifying these cases. Computed tomographic colonography (CTC) is currently an established technique for colorectal imaging that allows the evaluation of both endoluminal and transluminal features and has good diagnostic performance in T staging of colorectal cancer. Using CTC, images can be reconstructed in almost any plane and can be used to create three-dimensional images while maintaining diagnostic image resolution and without influencing the location of the lesion. It can also be used to evaluate both lesion morphology and intratumoral features, including those of protruding lesions and lesions located on the oral side of folds. Moreover, several studies have shown that the degree of fibrosis contributes to an enhancement pattern in contrast-enhanced CTC (CE-CTC). Thus, CECTC may potentially be used for evaluating the shape and morphological changes of the bowel wall, including the degree of fibrotic changes in the submucosal layer. In this letter, we describe the use of CTC in the identification of patients with intramucosal protruded-type neoplasm predicted to present endoscopic difficulties. All patients who had undergone preoperative colonoscopy and same day CE-CTC at our institution from January 2006 to December 2008 were identified through retrospective analysis. After pretreatment colonoscopy and standard preparation, patients underwent CE-CTC examination for staging using a 64-multidetector row CT scanner (Aquilion; Toshiba Medical Systems, Tokyo, Japan). The scan range was from the abdomen to the pelvis, with the following parameters: 120 kV; 200–400 mA with automatic exposure control; 64 rows×0.5 mm collimation; and helical pitch, 53 (pitch factor, 0.828). Anticholinergic drugs were injected intravenously immediately before each examination, and gas insufflation was performed via the anus with an T. Sakamoto (*) : T. Nakajima : T. Matsuda :Y. Saito Endoscopy Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan e-mail: tasakamo@ncc.go.jp

CT Colonography after Colorectal Cancer Resection: A One-Stop Assessment of Metachronous Mucosal Lesions, Local Recurrence, and Distant Metastases

Summary of ADC Measurements for Fetuses with and without Placental Insuffi ciency ParameterRegion 1 * Region 2 † Fetuses with Placental Insuffi ciency ( n = 33)Fetuses without Placental Insuffi ciency ( n = 69)Fetuses with Placental Insuffi ciency ( n = 33)Fetuses without Placental Insuffi ciency ( n = 69) Mean 1.454 1.771 1.415 1.752 Median 1.461 1.773 1.397 1.767 Standard deviation 0.106 0.208 0.132 0.181 Confidence interval 1.428, 1.498 1.705, 1.805 1.358, 1.455 1.686, 1.818 Note.— All measurements are given in 10 2 9 m 2 /sec. The average measurements of both readers are given. * Region 1 is located 2 cm from the insertion of the umbilical cord. † Region 2 is loca ted 5 cm from the insertion of the umbilical cord. “Reduction in False-Positive Results after Introduction of Digital Mammography: Analysis from Four Population-based Breast Cancer Screening Programs in Spain.” Radiology 2011;258(2):388–395 Page 388, the affi liations at the bot-tom left should read as follows: From the

CT colonography for postoperative surveillance after curative gastrectomy in patients with gastric cancer

The purpose was to evaluate the diagnostic role of contrast-enhanced CT colonography (CTC) for follow-up of colorectal cancer screening after curative gastrectomy in patients with gastric adenocarcinomas. Contrast-enhanced CTC was performed as a substitute for routine follow-up CT for the detection of recurrent lesions in 700 consecutive patients who underwent curative surgery for gastric adenocarcinomas. Prospectively, patients with polyps measuring 6 mm or larger on CTC were referred for optical colonoscopy. Clinical and radiologic follow-up with respect to detection of polyp and recurrent lesion was retrospectively assessed. Colorectal polyps measuring 6 mm or larger were identified by CTC in 104 (14.9%) of the 700 patients. Optical colonoscopy was recommended to these patients and was performed in 72 cases. True positive lesions were identified in 62 of the 72 patients (per-patient positive predictive value: 86.1%). The diagnostic yield for primary colonic malignancies was 1.6% (11/700). Recurrent lesions of gastric cancer were also detected in eight patients (1.1%). In patients who undergo gastrectomy due to gastric adenocarcinoma, contrast-enhanced CTC may offer a unique advantage by allowing simultaneous colorectal cancer screening in addition to its routine role of detecting recurrent lesions during follow-up.