Caecal carcinomas in the elderly: useful signs in minimal preparation CT

Accuracy of minimal-preparation computerized tomography in the investigation of suspected colorectal cancer in frail patients: the experience of Western General Hospital, Edinburgh

Traditional methods of investigating suspected colorectal carcinoma (CRC) such as barium enema, colonoscopy and computerized tomography (CT) pneumocolon are often poorly tolerated by frail or elderly patients. Comparatively, minimal-preparation CT (MPCT) is a non-invasive investigation that does not require bowel preparation. The aim of this study was to review MPCTs carried out at the Western General Hospital, Edinburgh, and compare findings with current published data. Retrospective analysis of 85 patients (age range 55-99 years) who underwent MPCTs at the Western General Hospital between May 2005 and June 2008 was undertaken. Results were followed up using clinical notes, pathological and surgical databases. Subsequent outcomes were analysed (average follow-up 22 months). The prevalence of CRC within the study cohort was 0.14. Sensitivity of MPCT was 1 (95% confidence interval [CI], 0.69-1) with a specificity of 0.93 (95% CI, 0.84-0.97). Thirty percent of patients were found to have extracolonic findings requiring further investigation or intervention. Of the patients, 4.7% had an extracolonic malignancy diagnosed on MPCT. MPCT is a sensitive and specific method of investigating CRC in the elderly, infirm or immobile. Our results were found to be comparable with that of current published data, validating the service provided at the Western General Hospital.

Caecal carcinoma: a review of 3 cases in a private hospital in Lagos

Colorectal tumors are rare in the developing countries but common in the civilized world. With the event of westernization of the diet, the incidence is increasing in the developing countries such as Nigeria. Caecal tumors present late because of the anatomical features of this part of colon. The tumors in the caecum are insidious in onset and often attend large size. Barium enema and colonoscopy have limitation in accessing this region. Computed tomography (CT) scan is expensive and not readily affordable in the developing world. High index of suspicion is therefore necessary to the diagnosed carcinoma of the caecum as it is a curable disease if diagnosed early and treated. We present 3 cases of caecal tumors seen over a 5-year period that were treated with good outcome.

Three-day regimen improves faecal tagging for minimal preparation CT examination of the colon

This study set out to determine whether extending the length of oral contrast administration in minimal preparation CT of the colon improves faecal tagging. Two cohorts of 50 patients each were compared, one with a 2-day the other with a 3-day faecal tagging regimen. The degree of faecal tagging was graded by two blinded observers. The 3-day regimen showed significantly better tagging in the rectum and sigmoid colon (p = 0.006 and p = 0.009, respectively, using the Mann-Whitney test). The percentage of patients who had faecal tagging in the sigmoid colon graded as "complete" was 64% for the 3-day regimen as opposed to 34% for the 2-day regimen. The corresponding percentages for the rectum were 64% for the 3-day regimen and 36% for the 2-day regimen. Extending the length of oral contrast administration from 2 to 3 days significantly improves the quality of faecal tagging in the rectum and sigmoid colon.

Computed tomographic colonography (CTC) performance: one-year clinical follow-up

AIM

Computed tomographic colonography (CTC) represents a valuable advance in imaging technology for patients with colonic symptoms who are unfit for or fail to complete investigation with conventional techniques of colonoscopy or barium enema. The aim of this study was to examine whether CTC was sufficient to exclude colorectal cancer in such a population. As our patients were unfit for or unable to complete conventional investigations, we used 1 year clinical follow-up to exclude colonic malignancy.

MATERIALS AND METHODS

CTC examination was performed using multi-slice CT in patients fitting pre-determined criteria. All patients who had completed 12 months of follow-up after CTC were included. Data were extracted from patient records and lack of presentation within the 12 months following a negative CTC was assumed to equate to lack of colorectal cancer at initial investigation.

RESULTS

One hundred and twelve patients underwent CTC with a median age of 78 years (range 39-95) and median follow-up of 18 months (range 12-26). CTC detected 7 colorectal cancers, with 3 false positives and 1 false negative, giving a sensitivity of 87.5% and specificity of 97.1% for the detection of colorectal cancer.

CONCLUSIONS

CTC is a good imaging tool for the exclusion of colorectal cancer in a population unfit for or unable to complete colonoscopy or barium enema, with reasonable sensitivity and specificity for detection of colorectal cancer. However, the optimum investigative strategy for fitter symptomatic individuals is still debated and should be clarified by the results of ongoing randomised controlled trials.

Minimal preparation CT for the diagnosis of suspected colorectal cancer in the frail and elderly patient

Colorectal cancer is a common malignancy with an increased incidence in the elderly population. Traditional methods of evaluating this disease have included double contrast barium enema and colonoscopy. Unfortunately, in the frail and elderly patient, these investigations can be difficult to perform and are often not tolerated. Minimal preparation computed tomography (MPCT) of the colon has been suggested as an alternative in this patient population. In this technique, no bowel preparation is used apart from the administration of oral contrast medium. The patient is imaged only in the supine position, without per rectal insufflation of gas or barium. This article reviews the experience to date of MPCT in detecting colonic tumours, and compares its efficacy to the traditional methods. A meta-analysis of the studies allowed estimation of the pooled sensitivity of MPCT to be 83% (95% confidence interval: 76-89%), and pooled specificity to be 90% (95% CI: 85-94%). An added advantage of MPCT is the ability to identify extra-colonic pathology, and this aspect is also reviewed. In addition, the common radiological features and pitfalls in identifying colonic tumours by MPCT are discussed.

[Right colon diverticulitis]

Diverticulitis involving the right colon is uncommon in the Occident; only one case for every 300 cases of appendicitis occurs in Western countries compared to a ratio of 1/40-1/180 in Asia. The preferential localization of diverticula in the right colon among Asiatics is probably due to genetic factors. In Asia as in the West, a right colon diverticulum is more likely to cause hemorrhage than diverticulitis. The peak age of symptoms is 40-45 years and the sex ratio is 1:1. The patient most commonly presents with symptoms suggestive of acute appendicitis, acute localized peritonitis, or, more rarely, a psoas abscess. Clinical exam reveals an inflammatory mass in the right lower quadrant in 30% of cases; diffuse peritonitis, large abscesses, and fistulae are rare. Helical CT scan is the best tool for establishing the diagnosis and also helps to rule out other possible etiologies in the differential diagnosis-particularly a perforated right colon cancer. In noncomplicated cases with convincing evidence for the diagnosis by CT scan, a conservative (non-surgical) treatment with antibiotics is possible; a later stage colonoscopy will rule out other colonic lesions. More commonly, the correct diagnosis is only made after embarking on an appendectomy via a McBurney incision; the surgical strategy thereafter depends on the level of suspicion regarding the diagnosis and the extent and complexity of the diverticulitis. Therapeutic options may be conservative (appendectomy), limited (diverticulectomy, or extensive (ileocecal resection or right hemicolectomy). For complicated disease (abscess, localized perforation), an aggressive surgical approach is warranted. Surgical strategies need to be validated, particularly in the light of the increasing use of the laparoscopic approach for suspected appendicitis.

Minimal preparation computed tomography instead of barium enema/colonoscopy for suspected colon cancer in frail elderly patients: an outcome analysis study

AIM

To evaluate the efficacy of minimal preparation computed tomography (MPCT) in diagnosing clinically significant colonic tumours in frail, elderly patients.

MATERIALS AND METHODS

A prospective study was performed in a group of consecutively referred, frail, elderly patients with symptoms or signs of anaemia, pain, rectal bleeding or weight loss. The MPCT protocol consisted of 1.5 l Gastrografin 1% diluted with sterile water administered during the 48 h before the procedure with no bowel preparation or administration of intravenous contrast medium. Eight millimetre contiguous scans through the abdomen and pelvis were performed. The scans were double-reported by two gastrointestinal radiologists as showing definite (>90% certain), probable (50-90% certain), possible (<50% certain) neoplasm or normal. Where observers disagreed the more pessimistic of the two reports was accepted. The gold standard was clinical outcome at 1 year with positive end-points defined as (1) histological confirmation of CRC, (2) clinical presentation consistent with CRC without histological confirmation if the patient was too unwell for biopsy/surgery, and (3) death directly attributable to colorectal carcinoma (CRC) with/without post-mortem confirmation. Negative end-points were defined as patients with no clinical, radiological or post-mortem findings of CRC. Patients were followed for 1 year or until one of the above end-points were met.

RESULTS

Seventy-two patients were included (mean age 81; range 62-93). One-year follow-up was completed in 94.4% (n=68). Mortality from all causes was 33% (n=24). Five histologically proven tumours were diagnosed with CT and there were two probable false-negatives. Results were analysed twice: assuming all CT lesions test positive and considering "possible" lesions test negative [brackets] (95% confidence intervals): sensitivity 0.88 (0.47-1.0) [0.75 (0.35-0.97)], specificity 0.47 (0.34-0.6) [0.87 (0.75-0.94)], positive predictive value 0.18 [0.43], negative predictive value 0.97 [0.96], positive likelihood ratio result 1.6 [5.63], negative likelihood ratio result 0.27 [0.29], kappa 0.31 [0.43]. Tumour prevalence was 12%. A graph of conditional probabilities was generated and analysed. A variety of unsuspected pathology was also found in this series of patients.

CONCLUSIONS

MPCT should be double-reported, at least initially. "Possible" lesions should be ignored. Analysis of the graph of conditional probability applied to a group of frail, elderly patients with a high mortality from all causes (33% in our study) suggests: (1) if MPCT suggests definite or probable carcinoma, regardless of the pre-test probability, the post-test probability is high enough to warrant further action, (2) frail, elderly patients with a low pre-test probability for CRC and a negative MPCT should not have further investigation, (3) frail, elderly patients with a higher pre-test probability of CRC (such as those presenting with rectal bleeding) and a negative MPCT should have either double contrast barium enema (DCBE) or colonoscopy as further investigations or be followed clinically for 3-6 months. MPCT was acceptable to patients and clinicians and may reveal significant extra-colonic pathology.

Preoperative staging of colorectal cancer--computed tomography and magnetic resonance imaging

Cross-sectional imaging techniques are increasingly being used in the preoperative evaluation of patients with colorectal cancer. Both computed tomography (CT) and magnetic resonance (MR) imaging have been improved with significant advances of the technological hard- and software. This has contributed to high patient acceptance due to shorter examination times and more open configuration of the systems, consistent high quality images with better delineation of the normal abdomino-pelvic anatomy and pathology. New techniques such as CT-colonography have emerged from a research application to a clinical tool which can be used in different clinical settings. Phased-array receiver coils have significantly increased the usefulness of MR in the evaluation of rectal neoplasms due to the high resolution that can be obtained. New organ specific contrast agents for magnetic resonance imaging have facilitated the preoperative evaluation of liver metastases in favour of more invasive techniques with similar sensitivities. However, preoperative staging criteria for colorectal cancer using computed tomography and magnetic resonance imaging has to be updated and the results of new techniques have to be confirmed in large trials. In the future, further development of CT and MR may offer 'one-stop-shopping' protocols for both diagnosis, local and distant staging of colorectal cancer. Diffusion weighted MR-imaging, in vivo spectroscopy as well as further targeted imaging, such as with lymph node specific agents for MR may also prove to be helpful in the preoperative evaluation of patients with colorectal cancer.