Minimal preparation CT: A literature review of a minimally invasive imaging technique for colorectal cancer in a frail, aged population

Abstract

SummaryColorectal cancer (CRC) is a common malignancy with increased incidence in the elderly. When CRC is suspected, patients are typically evaluated with optical colonoscopy (OC) or CT Colonography (CTC). Unfortunately, in the frail and elderly patient, these investigations can be difficult to perform and are often not tolerated. Minimal preparation computed tomography (MPCT) is a CT technique to evaluate the colon. Although protocols vary, typically, no preparation is required apart from administration of oral contrast for faecal tagging. The patient is scanned in the supine position only and without colonic insufflation. The study is reserved for 'old-old' frail patients with clinically suspected CRC who cannot tolerate or have failed OC or CTC. In the context of an ageing population, MPCT provides a simple, minimally invasive, readily available and well-tolerated test that is able to demonstrate clinically relevant disease. We review the literature on MPCT and discuss the benefits and limitations of this investigation.

Utility of minimal preparation computed tomography colonography in detecting colorectal cancer in elderly and frail patients

“…Our finding that no true positive cases in the cohort were reported as being equivocal for CRC is in concordance with previous recommendations that equivocal findings on MPCTC should not be reported/should be considered likely to be negative …”

“…Our results for MPCTC in the diagnosis of CRC are concordant with the recent systematic review by Csillag et al, 5 which identified 10 studies of varying study design, cohort size and diagnostic end-points. In our study, colorectal carcinoma and tubulovillous adenoma had an incidence of 10 patients (6.4%)well within the range of 4.6-18.9% reported by Csillag et al 5 Our sensitivity, specificity PPV and NPV are all within the ranges reported by Csillag et al: sensitivity of 75-100%, specificity of 84-96%, PPV of 26-75% and NPV of 96-100%.…”

“…Modifications to CTC have been proposed to reduce the side‐effects. These range from reducing the degree of catharsis to techniques that use neither catharsis nor insufflation . In our institution, the MPCTC protocol is limited to an extended faecal tagging protocol.…”

“…Frailty predisposes to complications that may occur from colonoscopy – such as metabolic effects of cathartic regimens and falls (such as those that may occur in needing to ambulate at night because of the catharsis).An important factor in the diagnosis of CRC in the elderly is the time lag between performing the screening test and preventing a death. Previous studies have shown that patients referred for MPCTC have a median survival of 5.4 years …”

“…catharsis to techniques that use neither catharsis nor insufflation. 5 In our institution, the MPCTC protocol is limited to an extended faecal tagging protocol. As there is no specific cathartic component (the oral contrast agent used does cause diarrhoea, but this is unlikely to be significant given the dilution and small quantity used), patient discomfort preceding the study is also reduced.…”