Added value of CT colonography after a positive conventional colonoscopy: impact on treatment strategy

Can Computed Tomography Colonography Replace Optical Colonoscopy in Detecting Colorectal Lesions?: State of the Art

Colorectal cancer is an important cause of morbidity and mortality worldwide. Optical colonoscopy (OC) is widely accepted as the reference standard for the screening of colorectal polyps and cancers, and computed tomography colonography (CTC) is a valid alternative to OC. The purpose of this review was to assess the diagnostic accuracy of OC and CTC for colorectal lesions. A literature search was performed in PubMed, Embase, and Cochrane Library, and 18 articles were included. CTC has emerged in recent years as a potential screening examination with high accuracy for the detection of colorectal lesions. However, the clinical application of CTC as a screening technique is limited because it is highly dependent on the size of the lesions and has poor performance in detecting individual lesions <5 mm or flat lesions, which, although rarely, can have a malignant potential.

Colorectal cancer: Parametric evaluation of morphological, functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

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.

Preoperative localization of colorectal cancer: a systematic review and meta-analysis

BACKGROUND

Preoperative colorectal tumor localization is crucial for appropriate resection and treatment planning. As the localization accuracy of conventional colonoscopy is considered to be low, several localization techniques have been developed. We systematically reviewed the tumor localization error rates of several preoperative endoscopic techniques and synthesized information on risk factors for localization errors and procedure-related adverse events.

METHODS

MEDLINE, EMBASE, the Cochrane Library, and the grey literature were searched. Studies were included if they reported tumor localization errors in patients with colorectal cancer undergoing resection with curative intent. Using random-effects models, pooled incidence of tumor localization errors were derived for conventional colonoscopy and colonoscopic tattooing. Due to the lack of comparative studies, a direct comparison of the pooled estimates was performed. Procedure-related adverse events, risk factors for localization errors, and the localization outcomes of other techniques such as colonoscopic clip placement, radioguided occult colonic lesion identification, and the use of magnetic endoscope imaging were also synthesized.

RESULTS

A total of 38 non-randomized controlled and observational studies were included in this review (2578 patients underwent conventional colonoscopy and 643 colonoscopic tattooing). The pooled incidence of localization errors with conventional colonoscopy was 15.4 % (95 % CI 12.0-18.7), whereas that of colonoscopic tattooing was 9.5 % (95 % CI 5.7-13.3), mean difference 5.9 % (95 % CI 0.65-11.14, p = 0.03). Adverse events secondary to tattooing were infrequent, and most were cases of ink spillage. Limited information was available for other localization techniques.

CONCLUSION

Conventional colonoscopy has a higher incidence of localization error compared to colonoscopic tattooing for localization of colorectal cancer. Colonoscopic tattooing is safe and leads to fewer tumor localization errors. Given the widespread adoption of laparoscopic resections for colorectal cancer, routine colonoscopic tattooing should be adopted. However, studies directly comparing different localization techniques are needed.

Recommendations and expert opinion on the treatment of locally advanced rectal cancer in Spain

In Spain 22,000 new cases of colorectal cancer are diagnosed each year, with 13,075 deaths resulting from this disease. Around 70% of colorectal cancers are localised in the colon and 30% in the rectum. A group of Spanish experts established recommendations on what would be the best strategy in the treatment of locally advanced rectal cancer (LARC). Adequate assessment of local tumour extension, including high-resolution magnetic resonance imaging and endorectal ultrasound, is essential for successful treatment. The three cornerstones in the treatment of LARC are surgery, radiotherapy and chemotherapy. Most patients will need a total mesorectal excision (TME). Preoperative chemo-radiotherapy (CRT) is preferred for the majority of patients with T3/T4 disease and/or regional node involvement, and adjuvant chemotherapy is recommended after a patient-sharing decision. Capecitabine, after showing a trend in improved downstaging in neoadjuvant stratum and the convenience of its oral administration, represents an alternative to 5-FU as perioperative treatment of LARC.

Colorectal cancer

Substantial progress has been made in colorectal cancer in the past decade. Screening, used to identify individuals at an early stage, has improved outcome. There is greater understanding of the genetic basis of inherited colorectal cancer and identification of patients at risk. Optimisation of surgery for patients with localised disease has had a major effect on survival at 5 years and 10 years. For rectal cancer, identification of patients at greatest risk of local failure is important in the selection of patients for preoperative chemoradiation, a strategy proven to improve outcomes in these patients. Stringent postoperative follow-up helps the early identification of potentially radically treatable oligometastatic disease and improves long-term survival. Treatment with adjuvant fluoropyrimidine for colon and rectal cancers further improves survival, more so in stage III than in stage II disease, and oxaliplatin-based combination chemotherapy is now routinely used for stage III disease, although efficacy must be carefully balanced against toxicity. In stage II disease, molecular markers such as microsatellite instability might help select patients for treatment. The integration of targeted treatments with conventional cytotoxic drugs has expanded the treatment of metastatic disease resulting in incremental survival gains. However, biomarker development is essential to aid selection of patients likely to respond to therapy, thereby rationalising treatments and improving outcomes.

Computed tomography colonography: advantages and main points

AIM: To evaluate the advantages of computed tomography (CT) colonography and to summarize the main points for CT colonography.

METHODS: Multislice CT colonography was performed in 46 patients with suspected colonic diseases, of which some patients underwent CT colonography in both the supine and prone positions. Different post-processing techniques such as multiplanar reformation (MPR), CT virtual colonoscopy, shaded surface display, Raysum and virtual pathology were employed to evaluate the mucosal and peripheral appearance of the colon.

RESULTS: Eleven patients showed negative results. Eleven patients were diagnosed as colon polyps, of which one had familial colonic polyposis. Sixteen patients were diagnosed as malignant lesions, of which 2 showed local thickening of the colon wall and 14 showed mass lesions. Five patients were diagnosed as inflammatory diseases.

CONCLUSION: The location, size, density and adjacent invasion of colon lesions can be evaluated objectively by CT colonography. The main points for CT colonography include sufficient cleansing of the colon lumen, adequate air injection, and combination of multiple post-processing techniques.

Advances in alimentary tract imaging

Advances in imaging techniques are changing the way radiologists undertake imaging of the gastrointestinal tract and their ability to answer questions posed by surgeons. In this paper we discuss the technological improvements of imaging studies that have occurred in the last few years and how these help to better diagnosing alimentary tract disease.