CT COLONOGRAPHY WITH THREE-DIMENSIONAL PROBLEM-SOLVING FOR DETECTION OF COLONIC POLYPS
Summary: Objective: We performed CT colonography in patients referred for conventional colonoscopy, interpreted the axial images, and used commercially available software to reconstruct endoluminal perspective views to differentiate polyps from folds. Subjects and Methods: We prospectively examined 44 patients (27 men and 17 women; mean age, 58 years old) with CT colonography by interpreting the axial images and using only three-dimensional rendering form problem solving. The CT scans were interpreted by two radiologists who were unaware of patient histories as revealed by colonoscopic findings. The findings on colonography were compared with those of conventional colonoscopy to determine sensitivity, specificity, time spent on interpretation, and confidence of interpretation. Results: Colonoscopy showed normal findings in 28 patients and 22 polyps in the remaining 16 patients. Six polyps were 8 mm or larger, 3 were 5-7 mm, and 13 were 5 mm or smaller. The findings of the two observers revealed an overall sensitivity of 50% and 38%, respectively, and a specificity of 93% and 86%K respectively. Sensitivity for polyps larger than 8 mm was 83% and specificity was 100% for both observers. The average amount of time spent on interpretation was 28 min 30 sec (range, 14-65 min). Both observers used the endoluminal view for differentiating folds from polyps in 23 (52%) of 44 patients, which had only minimal impact on interpretation time. Conclusion: CT colonography can be performed and the images interpreted using currently available hardware and software by initially using the axial images to search for polyps of significant size. Endoluminal views should be used only when necessary to help distinguish normal folds from fixed raised lesions that are suggestive of polyps.
Comment: CT colonography, known as "virtual colonoscopy" is one of the latest radiologic innovations for visualization of endoluminal perspective of the colon. Like virtual bronchoscopy, it consists mainly of three-dimensional rendering of axial high resolution CT sections, acquired by helical CT, with implementation of proprietary or commercially provided hard- and softwares. The technic, will enable the physician to bypass conventional colonoscopy, while elaborating comparable accuracy in the detection of luminal abnormalities of the colon. Conventional colonoscopy is certainly unpleasant to some demanding patients, and regarded as invasive in some way, therefore , provision of a three dimensional pictorial modality, instead of instrumental appears very attractive for endivision. The investigation of colonic polyps and their potential malignant transformation, in a suspicious setting, has been the desired aim of every radiologist, as well as the endoscopist. Until recently, these parallel or complementary procedures have been implemented to the best advantage. Our experience with air contrast study for the right colon and concomitant with colonoscopy for the left colon, where colonoscopy is not always accessible, have provided a high degree of accuracy for visualization of polyps down to a few millimeter in size. The newcomer virtual colonoscopy, apart from the requirement of sophisticated equipments, such as helical CT, three-dimensional rendering work station and complex programs, does not appear clinically promising for the developing countries when effectiveness is taken into account. It can hardly surpass the routine technics, and practical difficulties will certainly arise from the lack of appropriate technology and sophisticated tools.
Saeed Rad, M.D., Tabriz,
Iran
Source: Abration H, Dachman et al. AJR 1998; 177:989-95
SYMPTOMATIC GASTROESOPHAGEAL REFLUX AS A RISK FACTOR FOR ESOPHAGEAL ADENOCARCINOMA
Summary: Background: The causes of adenocarcinomas of the esophagus and gastric cardia are poorly understood. We conducted an epidemiologic investigation of the possible association between gastroesophageal reflux and these tumors. Methods: We performed a nationwide, population base, case-control study in Sweden. Case ascertainment was rapid, and all cases were classified uniformly. Information on the subjects' history of gastroesophageal reflux was calculated by logistic regression, with multivariate adjustment for potentially confounding variables. Results: Of the patients interviewed, the 189 with esophageal adenocarcinoma and the 262 with adenocarcinoma of the cardia constituted 85 percent of the 529 patients in Sweden who were eligible for the study during the period from 1995 through 1997. For comparison, we interviewed 820 control subjects from the general population and 167 patients with esophageal squamous-cell carcinoma. Among persons with recurrent symptoms of reflux, as compared with persons without such symptoms, the odds ratios were 7.7 (95 percent confidence interval, 5.3 to 11.4) for esophageal adenocarcinoma and 2.0 (95 percent confidence interval, 1.4 to 2.9) for adenocarcinoma of the cardia. The more frequent, more severe, and longer lasting the symptoms of reflux, the greater the risk. Among persons with long standing and severe symptoms of reflux, the odds ratios were 43.5 (95 percent confidence interval, 18.3 to 103.5) for esophageal adenocarcinoma and 4.4 (94 percent confidence interval, 1.7 to 11.0) for adenocarcinoma of the cardia. The risk of esophageal squamous-cell carcinoma was not associated with reflux (odds ratio, 1.1; 95 percent confidence interval, 0.7 to 1.9). Conclusions: There is a strong and probably causal relation between gastroesophageal reflux and esophageal adenocarcinoma. The relation between reflux and adenocarcinoma of the gastric cardia is relatively weak.
Comment: The following are now accepted facts: 1) the incidence of adenocarcinoma of the distal esophagus has risen dramatically in the past few decades; 2) Barrett's esophagus is a precursor of adenocarcinoma of the lower esophagus; 3) treatment of gastrointestinal reflux, whether surgical or medical, does not alter the risk of adenocarcinoma of the lower esophagus. To the above truths, can be added: 1) cancer of the esophagus, of the squamous cell variety, has a very high incidence in Iran, perhaps the highest in the world; 2) cancer of the stomach, including the cardia, is also very high in Iran, but no statistics on this particular condition (unlike esophageal squamous cell cancer) are available. Putting all these together, the following statements can be offered for Iranian physicians: 1) There is no reason to embark on any screening procedures for Barrett's esophagus in Iran. This is something which can be left to investigators in western countries with greater resources available to them, especially when there are no data on the frequency of Barret's esophagus in Iran to justify such costly efforts here. 2) cancer of the stomach should receive greater emphasis, focusing first on the epidemiology of the disease. 3) If accurate and reliable data confirm a higher than expected incidence of gastric cancer in Iran, appropriate screening procedures for this disease should then be considered, since: 4) The only possible way to reduce the extremely high mortality of gastric (and cardia) cancer is to detect the disease in the very early stages of its progression.
Farrokh Saidi, M.D.,
Tehran, Iran
Source: N Engl J Med 1999; 340:825-31.
CHARACTERISTICS OF LONG-TERM RENAL TRANSPLANT SURVIVORS
Summary: Despite the high rates of rejection, allograft failure, and patient death in the early years of renal transplantation, some patients have done remarkably well. Forty-three (17 living related donor and 26 cadaver donor recipients) such patients with an allograft that functioned for 19 years or more (range, 19 to 29 years) were followed up at this center. The patients included 24 men and 19 women, with a mean age at transplantation of 29 years, of whom 39 were white and four were black. At most recent follow-up, the mean daily dose of azathioprine was 104 mg (range, 50 to 175 mg) and that of prednisone was 10 mg (range, 5 to 20 mg). Mean serum creatinine level was 1.6 mg/Dl (range, 0.7 to 5.4 mg/Dl). Acute rejection occurred in 14 (33%) patients. Nine patients had one episode and five patients had two episodes of acute rejection. Long-term risks to the recipients appeared in the form of coronary artery disease in 10 (23%) patients; malignancy in 13 (30%) patients, which included nine patients with skin malignancy; and chronic hepatitis C virus (HCV) infection in four patients, two of whom died of complications of liver failure. Other complications included avascular bone necrosis in five patients, which required total hip replacement in two patients; hyperlipidemia requiring treatment in 16 (37%) patients; posttransplantation diabetes mellitus in 10 (23%) patients after a median of 17.5 years (range, 1 to 23 years); and hypertension in 23 (53%) patients. There were seven deaths (three of coronary artery disease, two of liver failure, one each of sepsis and malignancy) and eight graft losses (five to death with function, two to chronic rejection, and one to focal and segmental glomerulosclerosis). Although long-term allograft success results in patients receiving minimal amounts of immunosuppression and having good renal function, long-term renal transplant survivors are at risk for significant morbidity even in the third decade posttransplantation.
Comment: The miracle of survival achieved by renal transplantation entails a whole series of complex economic and cultural issues, especially in the developing countries. The most common causes of death in renal transplant recipients are coronary artery disease, infection, malignancy, cerebrovascular disease, and liver disease. Chronic rejection and death are the two main causes of graft loss in long-term survivors, and immunological events have no major role in allograft rejection or patient loss as shown in this study, hence only minimal immunosuppression is felt to be needed in long-term survivors of renal allograft recipients. It has been shown that replacing cyclosporine by azathioprine in the immunosuppressive regimen after 6 months does not inversely affect renal or patient long-term survival. Yet, the introduction of cyclosporine has been associated with decreased acute rejection episodes and increased renal survival only in cadaveric renal allograft recipients in the first posttransplantation year. This indicates that cyclosporine replacement by azathioprine must be encouraged in developing countries after 6 to 12 months in living related and non-related renal transplantation respectively. Since cyclosporine is a very expensive drug and the number of transplanted patients is steadily growing in the developing countries, this policy will result in a major national saving without harming the patients, particularly in countries such as Iran where transplantation programs are partly or fully funded by the government.
Parviz Khajehdehi, M.D.,
Shiraz, Iran
Source: Peddi VR, Whiting J, Weiskittel PD, et al. Am J
Kidney Dis 1998 Jul; 32(1):101-6