Virtual colonoscopy vs conventional colonoscopy in patients at high risk of colorectal cancer--a prospective trial of 150 patients.

OBJECTIVE: Virtual colonoscopy (VC)/CT colonography has advantages over the well-documented limitations of colonoscopy/barium enema. This prospective blinded investigative comparison trial aimed to evaluate the ability of VC to assess the large bowel, compared to conventional colonoscopy (CC), in patients at high risk of colorectal cancer (CRC). METHOD: We studied 150 patients (73 males, mean age 60.9 years) at high risk of CRC. Following bowel preparation, VC was undertaken using colonic insufflation and 2D-spiral CT acquisition. Two radiologists reported the images and a consensual agreement reached. Direct comparison was made with CC (performed later the same day). Interobserver agreement was calculated using the Kappa method. Postal questionnaires sought patient preference. RESULTS: Virtual colonoscopy visualized the caecum in all cases. Five (3.33%) VCs were classified as inadequate owing to poor distension/faecal residue. CC completion rate was 86%. Ultimately, 44 patients had normal findings, 44 had diverticular disease, 11 had inflammatory bowel disease, 18 had cancers, and 33 patients had 42 polyps. VC identified 19 cancers--a sensitivity and specificity of 100% and 99.2% respectively. For detecting polyps > 10 mm, VC had a sensitivity and specificity (per patient) of 91% and 99.2% respectively. VC identified four polyps proximal to stenosing carcinomas and extracolonic malignancies in nine patients (6%). No procedural complications occurred with either investigation. A Kappa score achieved for interobserver agreement was 0.777. CONCLUSION: Virtual colonoscopy is an effective and safe method for evaluating the bowel and was the investigation of choice amongst patients surveyed. VC provided information additional to CC on both proximal and extracolonic pathology. VC may become the diagnostic procedure of choice for symptomatic patients at high risk of CRC, with CC being reserved for therapeutic intervention, or where a tissue diagnosis is required.

Misinterpretation of the chest x ray as a factor in the delayed diagnosis of lung cancer.

All patients in 1997 with a histologically proved diagnosis of lung cancer in Castle Hill Hospital in whom a full set of case notes and x rays could be retrieved were studied. All previous chest x rays were reviewed by a consultant chest physician and a radiologist, who were blinded to the eventual site of the lesion and the point at which a suspicious abnormality first appeared. Case notes were inspected to clarify the cause of any error. Fifty eight patients were eligible, 28 of whom had previous chest x rays. Of these 14 were found to be abnormal. A significant difference (p=0.007) in time from diagnosis to death was found between those with a missed abnormality, median (interquartile range, IQR) 105 (55-219) days and those with no previous abnormality, median (IQR) 260 (137-512) days. In the 14 in whom the diagnosis was missed the median (IQR) delay from first abnormal chest x ray to the eventual diagnostic x ray was 101 (48-339) days. A significant difference (p=0.001) was also found between the median (IQR) time from first abnormal chest x ray to start of treatment between those with missed abnormalities, 155 (115-376) days, and those with no previous abnormality on chest x ray, 51 (44-77) days. The most common reason (47%) for the diagnosis to be missed was failure of the radiologist reporting the x ray to recognise the abnormality. It is not unusual to find previous significant radiological abnormalities in patients in whom a diagnosis of lung cancer is later made. This leads to a diagnostic delay which has a significant effect on time to initiation of treatment and palliation of symptoms, although not necessarily to eventual outcome.

Volume detection threshold: quantitative comparison of computed radiography and screen-film radiography in detection of pneumothoraces in an animal model that simulates the neonate.

PURPOSE: To quantitatively compare computed radiography (CR) and screen-film radiography (SFR) in the detection of pneumothorax in an animal model that simulates the neonate. MATERIALS AND METHODS: Three rabbits underwent placement of 5-F catheters in the right pleural space. Eight CR and eight SFR images were obtained. Volume-controlled pneumothorax was induced by incrementally injecting 4 cm3 of air (24 cm3 total) and four CR and four SFR images were obtained after each injection. Four radiologists blindly viewed the images twice (eight readings per image, 1,600 total observations). A dichotomous yes-no score for the presence of pneumothorax was used to calculate the volume detection threshold (VDT), defined as the air volume at which 50% of the pneumothoraces can be detected. The authors plotted the likelihood of a pneumothorax against the air volume by using the confidence indicator. RESULTS: Intraobserver VDT values for CR and SFR were not significantly different. CONCLUSION: CR is as accurate as SFR in the detection of pneumothorax in this quantitative animal model.

Rabbit pneumothorax. Feasibility of an animal model to simulate neonatal pneumothorax.

RATIONALE AND OBJECTIVES: The feasibility of developing an animal model to simulate radiographic features of neonatal pneumothorax was investigated, and supine computed radiography (CR) and film-screen radiography (FS) images were compared. METHODS: 5-Fr pigtail catheters were inserted into the right pleural space of three New Zealand white rabbits. Two CR and two FS supine images were obtained using identical technique. After serial 4-mL injections of air, one CR and one FS supine image were obtained. The images were masked and randomized, and four radiologists reviewed the images for typical signs of pneumothorax. Chest computed tomography (CT) was performed before the injection of any air and after completion of the study. RESULTS: At zero-mL air volume, radiologists did not perceive a pneumothorax. As the air volume increased, the number of signs of a pneumothorax increased; there was no significant difference between CR and FS in the number of signs of pneumothorax detected at any volume. Chest CT confirmed that there was no unexplained air leak. The volume of air injected correlated with the calculated volume from the CT. CONCLUSIONS: This induced, volume-controlled, animal model simulated the supine radiographic features of neonatal pneumothorax.

Tc HMPAO-labelled white cell scintigraphy in Cröhn's disease of the small bowel.

99mTechnetium-hexamethyl propylene amine oxime (99mTc HMPAO) white cell scintigraphy is increasingly used in the investigation of inflammatory bowel disease. It is now an accepted technique in the assessment of patients with colitis, although its role in small bowel is less clear. A retrospective study was performed on patients with jejunal and ileal Cröhn's disease to assess the sensitivity, reliability and usefulness of this technique in small bowel disease. Tc HMPAO scintigraphy was compared with barium studies, clinical outcome and, where available, subsequent histology. Good correlation between this technique and barium studies was found in 14 out of 18 patients and additional information was provided in two patients. A single false positive scan highlights the importance of early scanning in avoiding errors of interpretation due to the normal hepatobiliary excretion of activity that occurs with this pharmaceutical.

Case report: hepatic and splenic calcification due to amyloid.

A case of marked hepatic and splenic calcification due to primary amyloidosis is presented. Although the patient had been treated with continuous ambulatory peritoneal dialysis, there was no evidence of a causal relationship with the calcification. Amyloid is known to have an affinity for calcium, but this radiographic manifestation has not been previously reported.

Percutaneous transluminal angioplasty of the subclavian artery.

A series of 12 consecutive cases of symptomatic subclavian artery stenosis or occlusion treated by percutaneous transluminal angioplasty are described. In seven cases stenoses were successfully dilated, and in four out of five cases occlusions were recanalised using standard angioplasty technique. Complications were trivial and did not prolong hospital stay, all patients being discharged within 48 h of the procedure. Percutaneous transluminal angioplasty of the subclavian artery is a safe, effective procedure and recommended as the treatment of first choice in symptomatic subclavian stenosis or occlusion.