When perforation is not the culprit : case report and systematic review of mechanical small-bowel obstruction complicating colonoscopy.

Colonoscopy is generally safe, although expansion of colorectal cancer prevention programs is likely to increase the number of post-colonoscopy complications. We report the case of a 42-year old woman with a prior history of 2 cesarean section deliveries who developed abdominal pain after an otherwise uneventful screening colonoscopy. Urgent exploration revealed closed-loop obstruction involving the terminal ileum, caused by an adhesive band close to the site of her previous Pfannenstiel incision. A systematic review of the literature revealed 11 reports (1985-2008) describing a total of 13 cases of mechanical small bowel obstruction (MSBO) after colonoscopy, 9 of which were confirmed by laparotomy. Colonoscopy-induced MSBO is practically impossible to anticipate, and only a prior history of abdominal/pelvic surgery may be deemed as a predisposing factor. However, it is related to significant morbidity, as it often leads to an ischemic bowel with need for surgical resection. Thus, endoscopists should be aware and maintain a low operative threshold to this rare, but hazardous, complication of colonoscopy.

Radiation dose in repeated CT guided radiofrequency ablations.

OBJECTIVE: To calculate the cumulative effective and skin doses in patients that underwent repeated CT guided radiofrequency ablations (RFA). MATERIALS AND METHODS: From all patients that had undergone RFA during a five years period those which had three or more RFAs were selected. Using the CT images DICOM data, the dose length product (DLP), effective dose (E), skin dose profiles as well as the peak skin dose (PSD) were calculated, using appropriate methods and software developed for this purpose. For each patient, cumulative DLP and E were also calculated from the sum of the respective figures of each individual procedure. To calculate PSD, the skin dose profiles of each procedure were overlaid on the same Z-axis scale using anatomical landmarks for reference and the skin doses to each point were summed up. RESULTS: Five patients were studied; four had undergone 3 RFAs and one 10 RFAs. Cumulative DLP, E and PSD ranges were 5.6-22.3 Gy cm, 0.08-0.36 Sv and 0.8-3.4 Gy, respectively. Median E and PSD values per RFA were 35 mSv and 0.4 Gy, respectively. For comparison purposes it must be noted that in this CT department a routine abdomen-pelvis scan results to an E of about 10 mSv. CONCLUSIONS: Patients that undergo repeated RFAs are exposed to considerably high radiation exposure levels. When these patients are in the final stage of malignant diseases, stochastic effects may not be of major concern. However, optimization of the exposure factors and monitoring of these patients to avoid skin injuries are required.

What are the clinical and technical factors that influence the kerma-area product in percutaneous coronary intervention?

The purpose of the paper is to define predictors of the kerma-area product (KAP) in percutaneous coronary intervention (PCI). Two new digital X-ray interventional cardiology systems recently installed were included. A total of 398 PCI procedures were carried out by 6 board-certified senior interventional cardiologists with more than 15 years' experience and good knowledge of radiation protection measures. Clinical, radiation and procedural data were collected based on a detailed protocol developed by the SENTINEL cardiology subgroup. Correlation with clinical and procedure factors was then investigated. A significant correlation was found between fluoroscopy time and (i) lesion classification, (ii) the level of tortuosity and (iii) the number of vessels treated. No statistically significant differences were observed in the complexity of the case between operators. However, large differences were found in the KAP among operators, which were mostly attributed to the different number of frames taken by each operator. There was no statistically significant correlation between complexity and the total number of frames. The study showed that, in certain circumstances, the clinical need to successfully perform PCI takes precedence over radiation safety concerns.

Patient skin dose assessment during CT-guided interventional procedures.

The purpose of this study was to investigate patient skin doses in the most frequent computed tomography-guided interventional radiology procedures. The study includes 14 abdominal biopsies and 15 radiofrequency (RF) ablations. Patient skin dose was assessed by slow verification films. The technical factors recorded were: tube kilovoltage (kVp), tube load (mAs), slice thickness and the total number of slices (S). The median value of maximum entrance skin dose (ESD(M)) in biopsy was 108 mGy (9.5-282 mGy). S had a range of 4-152 with a median of 44 slices. Significant correlation was found between S and dose (r = 0.80). Median ESD(M) in RF ablation was 238 mGy (104-500 mGy). S had a range of 108-175 with a median of 155 slices. No significant correlation was found between S and dose. The large range of results show that a more extensive investigation should be performed. In summary, diagnostic procedures such as biopsy present patient skin doses that are relatively low. On the other hand, patient skin dose in RF ablation can be high and can reach values higher than the value that a slow verification film is capable of measuring (1.2 Gy). For these procedures, an alternative method should be investigated.

Optical density variations in CT films and their effect on image quality.

It was recently reported that optical density (OD) variations were observed in CT films printed with a laser camera, depending on the printing format and the frame position within the film. The purpose of the present study was to investigate if these variations are common to both laser and dry-film printers and if the different OD settings along with day-to-day and frame-to-frame variations may affect the image quality. Eight laser and five dry-film printers installed at 12 different CT facilities were tested. For each one, the SMPTE test pattern was printed on all frames of a film using the same printing format. The ODs of the 0%, 10%, 40% and 70% patches of the 11-step greyscale of the SMPTE patterns were measured with a densitometer in all frames, while all films were examined on a viewing box to assess subjectively the image quality by visual inspection of the test pattern. A wide range of OD settings and variations were recorded. Frame-to-frame variations in the same film of up to 0.19, 0.15 and 0.21 OD, were observed for contrast index (CI, the OD difference of patches 10% and 70%), speed index (SI, the OD of patch 40%) and maximum OD (OD(max), the OD of patch 0%), respectively. The variations were not always of the same magnitude, nor always followed the same pattern, even for printers of the same model. Considering all films and frames, the CI ranged from 1.26 to 1.74, the SI from 0.68 to 1.43 and the OD(max) from 2.5 to 3.11 OD, well beyond the proposed settings and tolerances of 1.55+/-0.15, 1.15+/-0.1 and 2.45+/-0.1 given in the literature for CI, SI and OD(max), respectively. Despite these large differences, the various problems that were identified in image quality from the visual inspection of the films could not be directly attributed to OD settings, as films with similar CI, SI and OD(max) presented quite different image quality levels. Therefore, for routine quality control, thorough visual inspection of the SMPTE test pattern provides all the necessary information about the imaging chain status.

Virtual bronchoscopy versus thin section computed tomography in evaluation of moderate and low grade stenoses: receiver operating characteristic curve analysis.

PURPOSE: To evaluate the impact of virtual bronchoscopy, under proper threshold settings, on observer level of confidence in the assessment of bronchial abnormalities producing stenoses < or = 75% compared to interpretation of thin section computed tomography (CT) images. MATERIAL AND METHODS: Sixty-five patients with fiberoptic bronchoscopy positive for tracheobronchial abnormalities were evaluated in a blinded observer study using a commercially available virtual endoscopy software package. The findings of virtual endoscopy were compared with those of fiberoptic bronchoscopy using receiver operating characteristic curves (ROCs) and other statistical tools. RESULTS: A total of 102 lesions were identified by fiberoptic bronchoscopy, with 44 of these producing bronchial stenoses < or = 75%. Concerning the latter lesions, for virtual bronchoscopy the areas under the ROCs were 0.93 and 0.96 for the two observers, respectively, while for thin section CT the corresponding values were 0.86 and 0.88; the differences observed were statistically significant. Contrary to thin section CT, virtual bronchoscopy did not show statistically significant differences from fiberoptic bronchoscopy regarding estimation of degree of stenosis. CONCLUSION: Virtual bronchoscopy under proper threshold settings has a statistically significant impact on observer performance where moderate and low-grade bronchial stenoses are concerned and gives an estimate of the degree of stenosis more precisely than thin section CT.

Radiation doses to patients from enteroclysis.

The purpose of this study was to determine the patient doses during enteroclysis and compare them with the available bibliographical data. For 14 enteroclysis examinations, the dose-area product (DAP) meter readings, fluoroscopy time, number of radiographs and exposure data were recorded. From these data, the fluoroscopy and radiography contributions to DAP, the entrance surface dose (ESD) and the effective dose (E) for each examination were estimated. The mean DAP was 81 Gy cm(2) and the mean fluoroscopy time was 19.5 min. The fluoroscopy contribution to DAP was 77% and 8.7 films were acquired in each examination on average. The mean ESD and E were estimated to be 428 mGy and 21 mSv, respectively. The mean DAP and fluoroscopy time calculated in this study are quite high when compared with those reported in the literature, suggesting that the examination technique should be reviewed and the ways to reduce patient exposure without compromising the diagnostic quality should be acquired.

Analysis of radiological examination request forms in conjunction with justification of X-ray exposures.

OBJECTIVES: To evaluate the adequacy of patient data and clinical information transmitted to the radiological departments by the referring clinicians in view of the justification demands concerning the radiological examinations, as those are described in the Radiation Protection Regulations of the European Union Nations. MATERIALS AND METHODS: Request forms for 1708 patients referred to radiology department and 410 referred to the CT department were evaluated concerning the proper completion of the form fields. Furthermore, for CT examinations a more detailed evaluation was carried out, to assess the rationalistic use of CT within the diagnostic algorithm. RESULTS: Not properly completed request forms to both departments were observed, however, the omissions were more prominent for the referrals to the radiology department, where the age and the probable clinical diagnosis was not given in 81.5 and 46% of the forms, respectively. Furthermore, the emergency indication was less cautiously used compared to the CT requests. For the CT department 33.3% of requests were justified and the final diagnosis was included in the referring doctor's probable clinical diagnosis. U/S was the examination of choice in 51% of the cases where an examination should have been performed before CT and in 70.6% of the cases where an alternative examination was proposed. CONCLUSIONS: The inadequate transmission of clinical information and the large number of not fully justified CT requests observed in this study are typical examples of the various problems that radiologists have to face in order to apply the justification directives.

Threshold selection in virtual bronchoscopy: phantom study and clinical implications.

PURPOSE: To investigate the effect of the threshold selection on the apparent diameter of a virtual bronchus and the virtual wall morphology and to examine the parameters that can affect the selection of the appropriate threshold for virtual bronchoscopy with single slice computed tomography. MATERIAL AND METHODS: A bronchial phantom containing plastic tubes simulating the airways of the tracheobronchial tree was constructed. The diameters of the virtual images of these tubes were measured using various thresholds for two different materials surrounding the tubes: air and water. These measurements were correlated with the density in HU of the walls. Furthermore, data from 20 virtual bronchoscopies in patients were retrospectively analyzed in the same way. RESULTS: The diameter of a virtual bronchus is strongly affected by the selected threshold. The appropriate threshold for accurate diameter representation depends on the density of the bronchial wall. CONCLUSION: Our results suggest that in clinical practice a single threshold value cannot be used for imaging all segments of the tracheobronchial tree. While a value of -520 is appropriate for the trachea and lobar segments, values down to -720 could be needed on the level of segmental and subsegmental bronchi. At these levels, a threshold value about 65 HU more negative than the value where the artificial holes appear on the virtual bronchial walls could be used.

Radiation doses to patients from endoscopic retrograde cholangiopancreatography examinations and image quality considerations.

The purpose of this investigation was to measure the dose-area product (DAP) and the other relevant dosimetric quantities in diagnostic and therapeutic endoscopic retrograde cholangiopancreatography (ERCP). Furthermore, the dependence of patient dose and image quality on the tube potential was investigated. A DAP meter was used for dose monitoring in seven diagnostic and 21 therapeutic ERCPs. For each ERCP the DAP meter readings, fluoroscopy time, number of radiographs and exposure data were recorded. From these data the fluoroscopy and radiography contributions to DAP, the entrance skin dose and the effective dose for each examination were estimated. For the investigation of the effect of tube potential on patient dose and image quality, a water phantom containing syringes filled with diluted contrast media was used. The average DAP was 13.7 Gy cm2 in diagnostic and 41.8 Gy cm2 in therapeutic ERCP whereas the average fluoroscopy times were 3.1 and 6.0 min respectively. DAP was strongly correlated to the fluoroscopy time. Measurements in the phantom showed that a good compromise between image quality and patient dose is obtained for tube potentials around 80 kV. Therapeutic ERCPs deliver on average higher doses to patients than diagnostic ERCPs. However, for a difficult diagnostic ERCP more patient exposure may be required than for a simple therapeutic ERCP.

Virtual CT cholangiography in patients with choledocholithiasis.

BACKGROUND: We evaluated the feasibility and accuracy of virtual computed tomographic cholangiography (VCTC) in detecting choledocholithiasis and imaging anatomic variations of the biliary tree. METHODS: Thirty-three consecutive patients with clinical and biological signs of choledocholithiasis underwent spiral CT after intravenous infusion of iotroxindimeglumine. Patients with total serum bilirubin levels above 3 mg/dL were not included in this study. Spiral data sets were used to construct intralumenal images of the biliary tree. The images were reviewed by two abdominal radiologists. The biliary ducts were divided into three segments, so the analysis was based on 99 segments. The diagnosis obtained by VCTC was compared with the final diagnosis established by endoscopic retrograde cholangiography or intraoperative cholangiography. RESULTS: VCTC correctly depicted biliary stones in nine of 10 patients and anatomic variations in all five patients, and no false-positive cases were observed. VCTC showed excellent endolumenal visualization of 87 of 99 segments of the biliary tree. The processing time (9.3 +/- 2.1 min) was particularly short. CONCLUSION: VCTC with intravenous infusion of iotroxindimeglumine may be a feasible clinical tool, with acceptable accuracy in selected cases.