Computed tomography evaluation of colorectal carcinoma

The Accuracy of Different Modalities Used for Preoperative Primary Tumour Localisation in Operated Colorectal Cancer Patients

Aim Colonoscopy and computed tomography (CT) scans of the abdomen and pelvis are routine pre-operative assessment tools in colorectal cancer (CRC) patients. There have been some discrepancies regarding the location of cancer when seen by colonoscopy versus CT scan. The purpose of this study was to compare the accuracy of a colonoscopy with a computed tomography (CT) scan of the abdomen and pelvis with contrast, which is done routinely before surgery to localise the exact site of the tumour within the large bowel, whilst comparing both to the operative, gross and histopathology findings of the exact location. Methods A retrospective study was carried out on 165 colorectal cancer patients operated on between January 1, 2010, and December 31, 2014, using electronic hospital records that were reviewed anonymously, comparing the location of cancer within the large bowels as was found on colonoscopy and CT scan of the abdomen and pelvis with contrast, comparing both to post-operative histopathology specimen or intra-operative assessment in cases where no resection of the primary tumour was performed. Results CT and colonoscopy were both accurate in diagnosing 70.5% of cases that had done both investigations pre-operatively. The best results were obtained when the cancer was located in the caecum as confirmed post-operatively; the combined accuracy rate was 100%. CT was accurate, whilst colonoscopy was not in eight (6.2%) cases (all are rectal or sigmoid cancers), and colonoscopy was accurate and CT was not in 12 cases, 10 of them were rectal and two were ascending colonic. Colonoscopy was not performed in 36 (21%) cases for a variety of reasons, including large bowel obstruction or perforation on presentation. In 32 of these cases, CT scan managed to accurately predict the location of cancer (mostly rectal and caecal), and CT scan was inaccurate in 20.6% of cases (34 out of 165), whilst colonoscopy was inaccurate in 13.9% of cases (18 out of 129). Conclusion Colonoscopy is more accurate in localising colorectal cancers than CT scan of the abdomen and pelvis with contrast. CT scan diagnoses regional and distant spread of colorectal cancers such as nodal status, invasion of neighbouring organs and/or peritoneum and the presence of liver metastases, whilst colonoscopy is limited to intraluminal diagnosis but can be both a diagnostic and therapeutic tool, with higher accuracy, in general, in localising colorectal cancers. Both CT scan and colonoscopy were equal in appendicular, caecal, splenic flexure and descending colon cancer localisation accuracy.

Implication of FDG-PET/CT in patients with potentially operable colorectal lung metastases

Objectives

This prospective study assessed the role of F-18-FDG-PET/CT in clinical staging for patients with colorectal cancer planned for pulmonary metastasectomy by thoracotomy or video-assisted surgery.

Patients and methods

In addition to conventional imaging, we performed 86 F-18-FDG-PET/CT studies in 76 patients with potentially resectable metastatic colorectal lung metastases. We then investigated the effect that PET/CT had on further clinical management. Based on the results from the 47 thoracotomies performed, we compared the number of pulmonary metastases discovered after histologic examination with the number predicted by the conventional computed tomography (CT) as an independent part of the F-18-FDG-PET/CT examination and by the F-18-FDG-PET component.

Results

F-18-FDG-PET/CT led to changes in treatment regime and diagnostic planning in many patients. In five patients PET/CT revealed previously undetected local recurrence of the primary colorectal cancer, in four patients hepatic metastases, in three patients bone metastases, in two patients soft-tissue metastases, and in three patients histologically preoperatively proven N2 or N3 station lymph node involvement. These all constituted exclusion criteria, and consequently the previously planned pulmonary metastasectomy was not performed. The sensitivity and positive predictive value (PPV) for detection of pulmonary metastases were 84.2% and 36.4% for CT and 75.0% and 61.6% for F-18-FDG-PET study. The calculated sensitivity, specificity, PPV, and NPV of F-18-FDG-PET/CT for detecting thoracic lymph node involvement were 85.7%, 93.0%, 66.7%, and 97.5%, respectively. Furthermore, we found that F-18-FDG-PET/CT may predict thoracic lymph node involvement based on the SUV of pulmonary nodules.

Conclusions

F-18-FDG-PET/CT has a clear role in the diagnostic workup for pulmonary metastatic colorectal cancer and may save patients from futile surgery. It cannot, however, be relied on to detect all possible pulmonary and nodal metastases, which surgeons must always consider when making treatment decisions.

Incomplete colonoscopy in patients with occlusive colorectal cancer: usefulness of CT colonography according to tumor location

PURPOSE

We sought to evaluate the clinical usefulness of CT colonography (CTC) after incomplete conventional colonoscopy (CC) for occlusive colorectal cancer (CRC) according to the tumor location.

MATERIALS AND METHODS

Seventy-five patients with occlusive CRC underwent subsequent CTC immediately after incomplete CC. Fifty-nine patients had distal CRC and 16 had proximal colon cancer. Experienced radiologists prospectively analyzed the location, length, and TNM staging of the main tumor. The colorectal polyps in the remaining colorectum and additional extraluminal findings were also recorded. Sixty-seven patients underwent colorectal resection. We retrospectively analyzed the surgical outcome and correlated CTC and CC findings.

RESULTS

The overall accuracies of tumor staging were: T staging, 86%; N staging (nodal positivity), 70% (80%); and intra-abdominal M staging, 94%. Additional colonic polyps were found in 23 patients. Six synchronous carcinomas were detected (9%); three in the proximal colon and three in the distal colon of occlusion. Clinically significant localization errors at CC were noted in 8 patients (12%, 5 proximal colon cancers and 3 distal CRCs) and were corrected by CTC. After CTC, the surgeons modified the initial surgical plan in 11 cases (16%).

CONCLUSION

In occlusive CRC, CTC is not only useful in the evaluation of the proximal bowel, but can also provide surgeons with accurate information about staging and tumor localization. CTC is recommended when endoscopists encounter occlusive CRC, regardless of tumor location.

CT virtual pancreatoscopy: a new method for diagnosing intraductal papillary mucinous neoplasm (IPMN) of the pancreas

BACKGROUND

We sought to validate computed tomographic virtual pancreatoscopy (CT-VP) created by multidetector row CT (MD-CT) in the clinical diagnosis of intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Five cases of pancreatic IPMNs were included in this study. A nasopancreatic drainage tube was inserted and the pancreatic duct was filled with contrast medium, after which an upper abdominal scan was performed by MD-CT. CT-VP and three-dimensional (3D) CT pancreatographic images were created using a workstation and compared with images by conventional diagnostic techniques. All cases were evaluated by endoscopic retrograde pancreatography (ERP) and three cases of main duct type were assessed by intraoperative real pancreatoscopy (RP).

RESULTS

In the main duct cases, papillary projections in the main pancreatic duct and branch orifices were clearly detected by CT-VP. These lesions and structures were confirmed by intraoperative RP, and the CT-VP images were clearer than RP images. In branch cases, a surface-rendering method allowed protruding lesions to be clearly detected in the dilated branches.

CONCLUSION

Compared with conventional ERP or RP, CT-VP and 3D-CT pancreatographic images were finer in quality, and the procedures were less invasive, faster, and less expensive. The potential shown by CT-VP with 3D-CT pancreatography in the clinical diagnosis of pancreatic IPMNs suggests that this approach may replace ERP in the near future.

Cost and effectiveness of follow-up examinations in patients with colorectal cancer resected for cure in a French population-based study

The cost of follow-up examinations for patients having undergone potentially curative surgery for colorectal cancer is considerable. The aim of this study was to provide a thorough assessment of the cost and effectiveness of the follow-up tests used during the 5 years after surgical resection for colorectal cancer and its recurrences. We studied medical and economic data from the records of 256 patients registered in the Herault Tumor Registry who underwent potentially curative surgical resection in 1992. Recurrence, curative recurrence, survival, and the cost of follow-up tests were assessed respectively for at least 5 years. We analyzed the cost and effectiveness of follow-up tests in patients who received either follow-up with carcinoembryonic antigen (CEA) monitoring as advocated by the 1998 French consensus conference recommendations (standard follow-up) or a more minimal follow-up schedule. Nine patients died in the postoperative period. The 5-year survival rates in the standard and minimal follow-up groups were 85% and 79%, respectively (p=0.25). Cost-effectiveness ratios were 2123 in Dukes' stage A patients, 4306 in Dukes' stage B patients, and 9600 in Dukes' stage C patients. Cost-effectiveness ratios for CEA monitoring and abdominal ultrasonography per patient alive in the standard follow-up group were 1238 and 2261.5, respectively. Cost-effectiveness ratios for CEA monitoring and abdominal ultrasonography per patient alive in the minimal follow-up group were 1478 and 573, respectively. There were no survivors 5 years after a recurrence when the recurrence was detected by physical examination, chest X-ray, and colonoscopy in either follow-up group. Dukes' classification is a poor indicator of patient selection. The follow-up tests should only include CEA monitoring and abdominal ultrasonography for the diagnosis of recurrence.

The value of immunoscintigraphy in the detection of recurrent colorectal cancer

The aim of this prospective study was to determine whether anti-carcinoembryonic antigen (anti-CEA) scintigraphy is a useful additional technique in the diagnosis recurrence of colorectal cancer. Forty patients with suspected recurrence of colorectal cancer, underwent immunoscintigraphy (IS) and helical computed tomography (CT) in the 2 weeks before surgery. Surgical findings were used to evaluate the performance of the imaging techniques. Suspected areas on IS and CT were systematically explored. Helical CT was found to be superior to IS for the liver, the sensitivity and specificity of CT being 100% and 90%, respectively, vs 53% and 100% for IS. However, IS was better than CT for the detection of extra-hepatic abdominal recurrence: sensitivity and specificity of IS were 100 and 82% respectively vs 33 and 82% for CT. Seven cases of peritoneal carcinomatosis were overlooked by helical CT. Our results indicate that IS improves detection of extra-hepatic abdominal recurrence of colorectal cancer. Immunoscintigraphy is valuable as a guide to the treatment strategy and operative procedures.

Rationale for bladder-sparing surgery in patients with locally advanced colorectal carcinoma

BACKGROUND

Total pelvic exenteration (TPE) with urinary diversion is a standard surgical approach for patients with locally advanced rectal carcinoma. Because only approximately 50% of patients undergoing TPE have tumor involving the bladder, the authors evaluated the feasibility of bladder salvage in this setting. The current study presents the results of a retrospective study of patients with advanced colorectal carcinoma (classification of >/= T3) to formulate criteria for selecting patients for bladder-sparing procedures.

METHODS

The charts of 81 patients with rectal carcinoma classified as >/= T3 were reviewed for age, gender, computed tomography (CT) findings, results of intraoperative examination under anesthesia, final pathologic evaluation, urologic complications, local recurrence, and patient survival.

RESULTS

Among the 46 patients who underwent TPE, final pathologic evaluation demonstrated tumor involvement of the bladder in 58% of patients. Preoperative identification of a bladder mucosal abnormality accurately predicted bladder involvement in only 57% of the 30 patients who underwent cystoscopy. CT and intraoperative palpation of the bladder individually predicted the final pathologic findings in 69% and 70% of patients, respectively; of the 21 patients in whom both were positive, 90% had bladder involvement. Of the 35 patients (26 females and 9 males) who underwent bladder-sparing procedures, 22 had complete sparing of the bladder, 9 underwent partial cystectomy (5 with ureteroneocystostomy), 4 underwent ureteroneocystostomy alone, and 2 underwent prostatectomy alone. Ninety-four percent of these 35 patients had negative histologic margins. There was no difference in the incidence rate of urinary complications between patients who underwent TPE and those who underwent a bladder-sparing surgery (17% each). The incidence rates of local recurrence (14% vs. 17%) and the 3-year survival rates (49% vs. 39%) did not differ significantly between the 2 groups.

CONCLUSIONS

Bladder-sparing surgery to treat patients with locally invasive colorectal carcinoma provides good local control without sacrificing survival. Women, whose reproductive organs act as a natural barrier, and selected men in whom CT and intraoperative evaluation identify only localized involvement of the prostate or bladder appear to be reasonable candidates for bladder-sparing procedures.

Diverticulitis versus colon cancer: differentiation with helical CT findings

PURPOSE

To retrospectively determine the computed tomographic (CT) signs associated with diverticulitis or colon cancer, and to prospectively apply these signs in the differentiation of these diseases.

MATERIALS AND METHODS

Fifty-eight CT scans in cases of proved diverticulitis (n = 27) or colon cancer (n = 31) were evaluated retrospectively by radiologists (blinded to the proved diagnosis) for the presence or absence of previously reported CT findings. These findings were correlated with the pathologic or final clinical diagnosis. The retrospective findings were applied in a prospective evaluation with a new set of 72 CT scans. The same five radiologists rendered a diagnosis according to a five-point confidence scale from definitely benign to definitely malignant. Individual and consensus readings were correlated with the final diagnosis.

RESULTS

Retrospectively, pericolonic inflammation (P < .01) and segment involvement greater than 10 cm (P < .012) were the most significant findings for diverticulitis; pericolonic lymph nodes (P < .0001) and luminal mass (P < .003) were the most significant findings for colon cancer. Prospectively, an unequivocal diagnosis was made correctly in 16 (40%) of 40 cases of diverticulitis and 21 (66%) of 32 cases of colon cancer.

CONCLUSION

When there are no pericolonic lymph nodes adjacent to a segment of colonic wall thickening, with pericolonic inflammatory changes, the most likely diagnosis is diverticulitis. When pericolonic lymph nodes are present, with or without pericolonic edema, the most likely diagnosis is colon cancer.

Rectal imaging and cancer

Rectal imaging has evolved substantially during the past 25 years and now offers surgeons exquisite anatomic detail and physiologic information. Dynamic cystoproctography, helical computed tomography, endoscopic ultrasonography, endorectal magnetic resonance imaging, and immunoscintigraphy have become standards for the diagnosis of rectal disease, staging of neoplasia, and survey of therapeutic results. The indications, limitations, and relative costs of current imaging methods are reviewed, and advances in imaging technology that promise future benefits to colorectal surgeons are introduced.

What's new in colorectal cancer screening?

There is now good evidence from case control studies and randomized controlled trials that screening average-risk subjects for colorectal cancer using faecal occult blood tests reduces mortality. There is limited data indicating that screening sigmoidoscopy can also achieve this. There is no evidence yet that screening by colonoscopy or double contrast barium enema can reduce mortality. Calculations of cost-effectiveness suggest that all of the above strategies should be economically worthwhile but there is no convincing evidence to suggest that one strategy is markedly more cost-effective than the others. Further data on several aspects of screening are required before any decisions are made on which form(s) of screening should be offered nationwide.