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

ESR Essentials: Imaging in colorectal cancer-practice recommendations by ESGAR

Colorectal cancer (CRC) is a significant global health concern. Diagnostic imaging, using different modalities, has a pivotal role in CRC, from early detection (i.e., screening) to follow-up. The role of imaging in CRC screening depends on each country's approach: if an organized screening program is in place, the role of CT colonography (CTC) is limited to the study of either individuals with a positive stool test unwilling/unable to undergo colonoscopy (CC) or in patients with incomplete CC. Although CC is the most common modality to diagnose CRC, CRC can be also incidentally detected during a routine abdominal imaging examination or at the emergency room in patients presenting with intestinal occlusion/subocclusion or perforation. Staging is a crucial aspect of CRC management, guiding treatment decisions and providing valuable prognostic information. An accurate local staging is mandatory in both rectal and colon cancer to drive the appropriate therapeutic workflow. Important limitations of US, CT, and MR in N-staging can be partially solved by FDG PET/CT. Distant staging is usually managed by CT, with MR and FDG PET/CT which can be used as problem-solving techniques. Follow-up is performed according to the general recommendations of the oncological societies. CLINICAL RELEVANCE STATEMENT: It is essential to summarize each phase of colorectal cancer workup, differentiating the management for colon and rectal cancer supported by the main international guidelines and literature data, with the aim to inform the community on the best practice imaging in colorectal cancer. KEY POINTS: • Colorectal cancer is a prevalent disease that lends itself to imaging at each stage of detection and management. • Various imaging modalities can be used as adjuncts to, or in place of, direct visualization methods of screening and are necessary for evaluating metastatic disease. • Reevaluation of follow-up strategies should be considered depending on patients' individual risk of recurrence.

Hydrocolonic Sonography: Description of the Technique and Its Application in a Case of Intracolonic Lipoma: Report about a Case

Intracolonic lipomas are benign lesions but can cause serious complications, especially when they are large. Regarding a 3 cm intracecal lipoma, we describe an ultrasound modality called a hydrocolonic ultrasound and how this technique can be used in the long-term follow-up of these lesions.

Pre-colectomy location and TNM staging of colon cancer by the computed tomography colonography: a diagnostic performance study

BACKGROUND

The Chinese Society of Clinical Oncology guidelines 2018 and the recent update of that (version 2020) recommends accurate examination before major treatment for decision(s) in cases of colon cancer. Also, the difficulty in the identification of the lesion during colectomy may lead to resection of a wrong segment of the colon or a more extensive resection than planned. Accurate pre-colectomy local staging of colon cancer is required to make decisions for treatment of colon cancer. The objective of the study was to evaluate the diagnostic performance of the computed tomography colonography (CTC) for pre-colectomy tumor location and tumor, node, and metastasis (TNM) staging of colon cancer.

METHODS

Data of preoperative colonoscopies, CTC, surgeries, and surgical pathology of a total of 269 patients diagnosed with colon cancer by colonoscopy and biopsy and underwent pre-colectomy location and TNM staging by CTC were collected and analyzed. The consistency between the radiological and the surgery/surgical-pathological for location and TN stages of colon tumor were estimated with the weighted kappa or kappa coefficient (κ) at 95% confidence interval (CI).

RESULTS

CTC detected 261 (93%) and colonoscopy detected 201 (72%) correct locations of tumors. Sensitivity and accuracy of CTC for detection of location of colon tumors were 100% and 92.58% (κ = 0.89; 95% Cl: 0.83-0.95). 72.48% sensitivity, 90.64% specificity, and 83.57% accuracy were reported for CTC in differentiation of tumors confined to the colon wall (T1/T2) from advanced tumors (T3/T4) (κ = 0.69, 95% Cl: 0.51-0.75). 81.01% sensitivity, 89.11% specificity, and 83.93% accuracy of CTC was reported for differentiation of tumors between low-intermediate risk and high risk (κ = 0.68, 95% Cl: 0.53-0.75). 69.31% sensitivity, 66.15% specificity, and 67.14% accuracy of CTC were reported for N staging of tumors (κ = 0.41, 95% Cl: 0.59-0.69).

CONCLUSIONS

CTC has high diagnostic parameters for pre-colectomy location and T staging of colon tumors except patients of colon cancer who received neoadjuvant chemotherapy.

LEVEL OF EVIDENCE

III.

TECHNICAL EFFICACY STAGE

2.

Accuracy of CT colonography in the preoperative staging of colon cancer: a prospective study of 217 patients

AIM

The purpose of the present study was to evaluate the accuracy of computed tomography colonography (CTC) in the preoperative localization and TN staging of colon cancer. CTC can be an effective technique for preoperative evaluation of colon cancer and could facilitate the selection of high-risk patients who may benefit from neoadjuvant chemotherapy.

METHOD

This was a prospective observational study conducted at a single tertiary-care centre. It involved 217 patients (225 tumours) who had colon cancer and underwent preoperative CTC and elective colectomy. The radiologist determined the TNM stage using postprocessing software with multiplanar images and virtual colonoscopy. The following criteria were analysed for every colon tumour: location, size and signs of direct colon wall invasion. The histopathological findings of the surgical colectomy specimens served as the reference standard for local staging.

RESULTS

CTC detected all tumours and achieved an exact location in 208 cases (92.4%). CTC findings changed the surgical plan in 31 patients (14.3%) following colonoscopy. The accuracy in differentiating T3/T4 vs T1/T2 tumours was 87.1%, with a sensitivity and specificity of 88.5% and 84.1%, respectively (kappa = 0.71). For high-risk tumours (T3 ≥ 5 mm and T4), CTC showed an accuracy, sensitivity and specificity of 82.7%, 86% and 80%, respectively (kappa = 0.65). The accuracy of N-stage evaluation was 69.3%, the sensitivity 74% and the specificity 67.1% (kappa = 0.37).

CONCLUSION

CTC provides accurate information for the assessment of tumour localization and T staging, allowing better surgical planning and also allows the selection of locally advanced tumours that may benefit from new treatments such as neoadjuvant chemotherapy.

Synchronous colorectal cancer using CT colonography vs. other means: a systematic review and meta-analysis

OBJECTIVES

The objective of our study was to systematically review the evidence about synchronous colorectal cancer diagnosed with or without computed tomography colonography (CTC).

MATERIALS AND METHODS

Two systematic searches were performed (PubMed and EMBASE) for studies reporting the prevalence of synchronous colorectal cancer (CRC): one considering patients who underwent CTC and the another one considering patients who did not undergo CTC. A three-level analysis was performed to determine the prevalence of patients with synchronous CRC in both groups of studies. Heterogeneity was explored for multiple variables. Pooled prevalence and 95% confidence interval (CI) were calculated. A quality assessment (STROBE) was done for the studies.

RESULTS

For CTC studies, among 2645 articles initially found, 21 including 1673 patients, published from 1997 to 2018, met the inclusion criteria. For non-CTC studies, among 6192 articles initially found, 27 including 111,873 patients published from 1974 to 2015 met the inclusion criteria. The pooled synchronous CRC prevalence was 5.7% (95% CI 4.7%-7.1%) for CTC studies, and 3.9% (95% CI 3.3%-4.4%) for non-CTC studies, with a significant difference (p = 0.004). A low heterogeneity was found for the CTC group (I² = 10.3%), whereas a high heterogeneity was found in the non-CTC group of studies (I² = 93.5%), and no significant explanatory variables were found. Of the 22 STROBE items, a mean of 18 (82%) was fulfilled by CTC studies, and a mean of 16 (73%) by non-CTC studies.

CONCLUSIONS

The prevalence of synchronous CRC was about 4-6%. The introduction of CTC is associated with a significant increase of the prevalence of synchronous CRCs.

Laparoscopic subtotal colectomy for synchronous triple colorectal cancer: A case report

Synchronous colorectal cancers refer to the simultaneous occurrence of multiple colorectal tumors in a single patient, excluding any metastases from other organs. At present, radical surgery is considered the standard curative treatment; however, individualized surgical strategies depend on tumor location, the depth of invasion and the general health of the patient. In the present study, the case of a 52-year-old man who presented with a 2-month history of abdominal pain that was accompanied by intermittent hematochezia and weight loss is reported. The patient had no family history of cancer. Computed tomography (CT) of the abdomen revealed intestinal wall thickness in the transverse colon and volvulus in the hepatic flexure of colon. Colonoscopy identified 3 tumors: The first tumor was located in the descending colon with lumen stenosis ~60 cm from the anal verge, the second tumor was located in the hepatic flexure of the colon, and the third tumor was located in the sigmoid colon, 23 cm from the anal verge. Subsequently, laparoscopic subtotal colectomy was performed and all three tumors were removed, and the diagnosis was confirmed by histopathological examination. The patient did not undergo chemotherapy following surgery, due to personal reasons. Subsequent to 19 months of follow-up examinations using CT and colonoscopy every 6 months, the patient exhibited no signs of recurrence. Thus, laparoscopic subtotal colectomy represents an effective surgical approach for the treatment of synchronous colorectal cancer following imaging and endoscopic diagnosis.

Prediction of synchronous colorectal cancers by computed tomography in subjects receiving an incomplete colonoscopy: A single-center study

AIM: To assess the value of computed tomography (CT) for diagnosis of synchronous colorectal cancers (SCRCs) involving incomplete colonoscopy.

METHODS: A total of 2123 cases of colorectal cancer (CRC) were reviewed and divided into two groups according to whether a complete or incomplete colonoscopy was performed. CT results and final histological findings were compared to calculate the sensitivity and specificity associated with CT for detection of SCRCs following complete vs incomplete colonoscopy. Factors affecting the CT detection were also analyzed.

RESULTS: Three hundred and seventy-four CRC patients underwent incomplete colonoscopy and 1749 received complete colonoscopy. Fifty-six cases of SCRCs were identified by CT, and 36 were missed. In the incomplete colonoscopy group, the sensitivity and specificity of CT were 44.8% and 93.6%, respectively. The positive and negative predictive values were 23.6% and 95.0%, respectively. In contrast, the sensitivity and specificity of CT for the complete colonoscopy group were 68.3% and 97.0%, while the positive and negative predictive values were 22.2% and 98.7%, respectively. In both groups, the mean maximum dimension of the concurrent cancers identified in the CT-negative cases was shorter than in the CT-positive cases (incomplete group: P = 0.02; complete group: P < 0.01) Topographical proximity to synchronous cancers was identified as a risk factor for missed diagnosis (P = 0.03).

CONCLUSION: CT has limited sensitivity in detecting SCRCs in patients receiving incomplete colonoscopy. Patients with risk factors and negative CT results should be closely examined and monitored.

Dual-energy CT colonography for preoperative "one-stop" staging in patients with colonic neoplasia

RATIONALE AND OBJECTIVES

To evaluate the benefits of dual-energy computed tomography (CT) colonography (DECTC) as a preoperative staging tool in patients with clinically suspected colorectal cancer (CRC).

MATERIALS AND METHODS

Twenty-two patients with colorectal neoplasia underwent preoperative abdominal DECTC on a dual-source scanner (SOMATOM Definition Flash; Siemens) operated at tube potentials of Sn140/100 kVp. Scans were evaluated for local tumor stage and the presence of synchronous intracolonic and extracolonic findings using dual-energy color-coded images. An enhancement ≥25 Hounsfield units (HU) was defined to indicate malignancy. Patients' effective doses were calculated.

RESULTS

Preoperative DECTC allowed for complete bowel evaluation in all patients, including subjects with stenosing CRC. DECTC revealed 22 carcinomas (mean enhancement, 47 ± 12 HU). In total, 22 synchronous intracolonic lesions were detected, including 19 adenomas (mean enhancement, 51 ± 19 HU). Benign structures showed enhancement <25 HU. Comparing DECTC to histopathology, 95% carcinomas and 71% synchronous lesions proximal to stenosing CRC could be verified. Mean estimated effective dose was 13.0 ± 5.2 mSv.

CONCLUSIONS

Preoperative DECTC can be used as an accurate and dose-efficient primary-staging examination. Especially after incomplete optical colonoscopy, virtual colonoscopy enables full preoperative colonic assessment on the same day. Dual-energy CT enables distinction between neoplasia and non-neoplastic findings within and outside the colon. Therefore, DECTC can be regarded as a promising "one-stop" staging examination in patients with clinically suspected CRC.

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: what radiologists need to know]

In 2008, CT colonography was approved by the American Cancer Society as a technique for screening for colorectal cancer. This approval should be considered an important step in the recognition of the technique, which although still relatively new is already changing some diagnostic algorithms. This update about CT colonography reports the quality parameters necessary for a CT colonographic study to be diagnostic and reviews the technical innovations and colonic preparation for the study. We provide a brief review of the signs and close with a discussion of the current indications for and controversies about the technique.