Cost-effectiveness of computed tomographic colonography: a prospective comparison with colonoscopy

Purpose: To estimate the cost-effectiveness of detecting colorectal polyps with computed tomographic colonography (CTC) and subsequent polypectomy with primary colonoscopy (CC), using CC as the alternative strategy.

Material and Methods: A marginal analysis was performed regarding 103 patients who had had CTC prior to same-day CC at two hospitals, H-I (n = 53) and H-II (n = 50). The patients were randomly chosen from surveillance and symptomatic study populations (148 at H-I and 231 at H-II). Populations, organizations, and procedures were compared. Cost data on time consumption, medication, and minor equipment were collected prospectively, while data on salaries and major equipment were collected retrospectively. The effect was the (previously published) sensitivities of CTC and CC for detection of colorectal polyps≥6 mm (H-I, n = 148) or ≥5 mm (H-II, n = 231).

Results: Thirteen patients at each center had at least one colorectal polyp≥6 mm or ≥5 mm. CTC was the cost-effective alternative at H-I (€187 vs. €211), while CC was the cost-effective alternative at H-II (€239 vs. €192). The cost-effectiveness (costs per finding) mainly depended on the sensitivity of CTC and CC, but the depreciation of equipment and the staff's use of time were highly influential as well.

Conclusion: Detection of colorectal polyps≥6 mm or ≥5 mm with CTC, followed by polypectomy by CC, can be performed cost-effectively at some institutions with the appropriate hardware and organization.     

What are radiologists doing to prevent contrast-induced nephropathy (CIN) compared with measures supported by current evidence? A survey of European radiologists on CIN associated with computed tomography

Background: Contrast-induced nephropathy (CIN) is a serious complication of the use of iodinated contrast media (CM), and is associated with increased morbidity and mortality.

Purpose: To investigate whether radiologists take sufficient measures to prevent CIN in computed tomography (CT).

Material and Methods: 2005 survey of 509 European radiologists who had ≥3 years' experience and performed ≥50 CT scans/week.

Results: The most common methods used to identify patients at risk of CIN were renal function measurements (64%), clinical judgment (55%), and patient questionnaires (31%); 9% made no routine attempt to identify at-risk patients. The most common preventive protocols used in at-risk patients included: intravenous (i.v.) saline volume repletion (59%) or oral hydration (52%) before/after CT; use of low-osmolar CM (LOCM; 40%) or isosmolar CM (IOCM; 36%); and N-acetylcysteine (20%); 8% used no hydration regimen. While 78% of respondents used ≤100 ml of CM in high-risk patients, 14% used ≤150 ml, and 9% set no volume limit. For 57% of respondents, osmolality was the most important attribute in choosing an iodinated CM in at-risk patients; 41% agreed that CIN risk is lower with IOCM versus LOCM (31% disagreed).

Conclusion: A European radiologist survey identified a need for increased implementation of evidence-based protocols to improve CIN prevention: routine identification of at-risk patients; withdrawal of nephrotoxic drugs; use of volume repletion regimens; lowest possible volume of CM; and appropriate CM.     

Preoperative computed tomography-guided percutaneous hookwire localization of metallic marker clips in the breast with a radial approach: initial experience

Background: Hookwire localization is the current standard technique for radiological marking of nonpalpable breast lesions. Stereotactic directional vacuum-assisted breast biopsy (SVAB) is of sufficient sensitivity and specificity to replace surgical biopsy. Wire localization for metallic marker clips placed after SVAB is needed.

Purpose: To describe a method for performing computed tomography (CT)-guided hookwire localization using a radial approach for metallic marker clips placed percutaneously after SVAB.

Material and Methods: Nineteen women scheduled for SVAB with marker-clip placement, CT-guided wire localization of marker clips, and, eventually, surgical excision were prospectively entered into the study. CT-guided wire localization was performed with a radial approach, followed by placement of a localizing marker-clip surgical excision. Feasibility and reliability of the procedure and the incidence of complications were examined.

Results: CT-guided wire localization surgical excision was successfully performed in all 19 women without any complications. The mean total procedure time was 15 min. The median distance on CT image from marker clip to hookwire was 2 mm (range 0-3 mm).

Conclusion: CT-guided preoperative hookwire localization with a radial approach for marker clips after SVAB is technically feasible.     

The rotation ratios method: a method to describe altered pelvic orientation in sequential radiographs

Background: A method to describe pelvic rotations between pairs of standard sequential pelvic anteroposterior radiographs based on a pelvic phantom is described in a former study.

Purpose: To expand this method into clinical use based on clinical data.

Material and Methods: Teardrop distances were measured on 262 pelvic radiographs from 46 patients in a clinical material using a computer program designed to perform measurements on digital radiographs. Anthropometric data recorded from 141 pelvises in an anatomical collection were employed in a computer program designed to simulate radiographs of virtual objects. Virtual rotations of the pelvises were carried out with 4653 virtual radiographs obtained. Virtual radiographic measures were analyzed.

Results: A statistically significant difference of 8 mm between mean teardrop distance in females (120 mm) and males (112 mm) was found in the clinical material. A set of formulas describing the relations between differences of two rotation ratios and pelvic rotations were derived. Four simple regression analyses were carried out with the use of virtual measures. Adjusted teardrop distances were implemented.

Conclusion: A clinical method to describe pelvic rotations using standard pelvic radiographs was developed.     

Technical optimization of four-channel multidetector-row helical computed tomography for depicting arterial stenosis: a phantom study

Purpose: To determine the effects of detector configuration, as well as vessel orientation, on the depiction accuracy of arterial stenosis using four-channel multidetector-row helical computed tomography (MDCT) angiography in vitro.

Material and Methods: Five acrylic vessel phantoms (3 mm in diameter with 25 or 50% stenosis, or 5 mm with 25, 50, or 75% stenosis) were scanned with a four-channel MDCT scanner at five vessel orientations (0, 30, 45, 60, and 90° to the z-axis) using 4×1.25, 2.5, 3.75, and 5.0-mm detector configurations at beam pitches of 0.75 and 1.5. The percentage of stenosis was calculated by the ratio of the full width at half maximum for stenotic and non-stenotic portions of the phantom, and compared to the actual known values.

Results: A detector configuration of 4×1.25 mm provided good reproducibility, as well as high accuracy for assessing vessel stenosis, while a 4×2.5-mm or wider detector configuration caused underestimations of stenosis. Although the phantoms perpendicular to the z-axis were underestimated, the errors were kept in clinically acceptable ranges using the 4×1.25-mm detector configuration.

Conclusion: Four-channel MDCT accurately discerns stenosis for vessel phantoms of 3 or 5 mm in diameter at any orientation when using a detector configuration of 4×1.25 mm.     

Multi-detector computed tomography angiography of the hepatic artery in liver transplant recipients

Purpose: To evaluate the ability of multi-detector row computed tomography angiography (CTA) in detecting hepatic artery complications in the follow-up of liver transplant patients, performing volume-rendering as reconstruction technique.

Material and Methods: The anatomy of hepatic artery was studied in 27 liver transplant recipients with a four-row CT scanner using the following parameters: collimation, 1 mm; slice width, 1 mm; table feed, 6-8 mm/s; spiral reconstruction time, 0.5 s; reconstruction interval, 0.5 mm; mAs, 160; kVp, 120. Before the study, the patients received 1000 ml of water as oral contrast agent to produce negative contrast in the stomach and the small bowel. A non-ionic contrast medium was infused intravenously at a rate of 5 ml/s with a bolus tracking system. Volume-rendering of hepatic artery was performed with the 3D Virtuoso software.

Results: The celiac trunk, the hepatic artery, and the right and left hepatic arteries were successfully displayed in high detail in all patients. Side branches, including small collaterals, and hepatic artery anastomosis could also be readily visualized. Volume-rendered CTA detected six hepatic artery stenoses, two hepatic artery thromboses, and two intrahepatic pseudoaneurysms. In two cases, CT detected hepatic artery stenosis with a diameter reduction of less than 50%, while digital subtraction angiography showed a normal artery.

Conclusion: Volume-rendered multi-detector CTA is a promising non-invasive technique, since it allows images of high quality to be generated with excellent anatomical visualization of the hepatic artery and its complications in liver transplant recipients.     

Computed tomography of the urinary tract: optimalization of low-dose stone protocol in a clinical setting

Purpose: To establish whether information would be lost if slice reconstruction thickness was increased from 3 to 5 mm, and whether this altered how difficult it was to interpret the examinations.

Material and Methods: Twenty-three consecutive patients referred with suspected or known urinary stones were included. All examinations were performed without intravenous contrast media. The original series, with effective mAs 50, were reconstructed with slice thickness 3 and 5 mm, respectively. All demographic and examination data were removed and the series reviewed in PACS by two independent radiologists. Objective findings, i.e. number and size of stones, signs of obstruction, and evaluation of interpretation difficulty, were registered.

Results: Identical findings were registered in 18 of the series of 3 mm (n = 23) and 19 of the series of 5 mm (n = 23). In two series reconstructed with 3 mm slice thickness and in one series with 5 mm slice thickness, the observers disagreed on the presence of urinary stones. Main reasons for interpretation difficulties were given as “lack of intra-abdominal fat” and “many phleboliths in the pelvic region”, but never “disturbing noise”.

Conclusion: To determine the presence and size of urinary stones at low-dose computed tomography, 5 mm reconstruction algorithm seems equal to 3 mm. Patient-related factors influence the interpretation more than image quality.     

Availability, indications, and technical performance of computed tomographic colonography: a national survey

Purpose: To determine the availability, indications, and technique of computed tomographic colonography (CTC) in Sweden and to investigate opinions on its future role in colon imaging.

Material and Methods: In May 2004, a questionnaire on CTC was mailed to all Departments of Radiology in Sweden, and one year later a telephone interview was conducted with the departments that intended to start a CTC service.

Results: Ninety-nine departments (83%) answered the questionnaire, indicating that 23/99 (23.2%) offered a CTC service. Reasons for non-implementation of CTC were lack of CTC training in 34/73 (46.6%) and non-availability of multi-detector row CT scanners in 33/73 (45.2%), while 26% were awaiting further scientific documentation on CTC. Incomplete colonoscopy was the main indication for CTC in 21/23 (91.3%) departments performing CTC. Dual positioning, room air insufflation, and thin-slice collimation were used in all the responding departments. The number of CTC studies performed varied from 1-5 (26.1%) to more than 200 (17.4%). Intravenous contrast material was routinely administered by 9/23 (39.1%) departments. Out of 30 (39.5%) departments that in 2004 intended to start CTC, 9 (30%) had done so by June 2005. A total of 32/99 (32.3%) departments had therefore started CTC by June 2005. Half of the departments that replied believed that CTC would absolutely or probably replace barium enema in the future.

Conclusion: The survey shows relatively limited diffusion of CTC practice in Sweden, with approximately one-third of radiology departments offering a CTC service, mostly on a small scale. A wider dissemination of CTC requires further scientific documentation of its capability, intensified educational efforts, and additional funding.     

Acceleration of primary liver tumor growth rate in embolized hepatic lobe after portal vein embolization

Background: Portal vein embolization (PVE) is now widely accepted as a useful preoperative procedure in selected patients undergoing extended hepatectomy. However, the effect of PVE on the growth of liver tumors has not been fully elucidated.

Purpose: To retrospectively evaluate the effects of PVE on the growth of liver tumors in the embolized lobes.

Material and Methods: Eight patients with a primary liver tumor, six hepatocellular carcinomas (HCC) and two cholangiocellular carcinomas (CCC), were studied. The growth rates of the tumors in the embolized lobes and non-embolized liver parenchyma were calculated using the computed tomography (CT) volume values at the time of tumor identification, and before and after PVE.

Result: The median tumor growth rate was 0.59 cm³/day (range 0.22-6.01 cm³/day) before PVE and 2.37 cm³/day (range 0.29-13.97 cm³/day) after PVE (P = 0.018). The tumor growth acceleration ratios ranged from 1.50 to 7.46 (median 2.65) in the six HCCs, and were 1.00 and 1.32 in the two CCCs. There was no apparent correlation between the tumor growth rate after PVE and the growth rate of non-embolized liver parenchyma (median 6.00 cm³/day, range 1.24-11.0 cm³/day).

Conclusion: Liver tumor growth in an embolized lobe accelerates after PVE, in patients with HCC.     

Percutaneous microductectomy with a directional vacuum-assisted system guided by ultrasonography for the treatment of breast discharge: experience in 63 cases

Background: Vacuum-assisted devices are becoming a useful tool in the diagnosis and treatment of breast pathology. Recent publications show good results in percutaneous removal of benign lesions.

Purpose: To discuss our experience in percutaneous excision of ductal lesions with a vacuum-assisted, ultrasound-guided directional system.

Material and Methods: From January 2003 to July 2006, 63 patients with pathological nipple discharge and intraductal lesion identifiable on imaging were studied at two reference centers. Percutaneous excision with a vacuum-assisted device was offered as an alternative to surgery.

Results: A total of 71 lesions were diagnosed in 63 patients with a mean age of 52 years. All the patients presented nipple discharge. Mammography was normal in 65 cases (92%). Galactography showed an intraductal lesion in 67 cases (94%). Mean lesion size on ultrasonography was 7.4 mm (2-26 mm). Percutaneous excision was performed in 45 lesions (63%), while surgical excision was indicated in 26 lesions. The histopathological results in the 45 lesions biopsied demonstrated intraductal papilloma in 30 cases, dilated duct with papillomatous projections in 11, ductal ectasia with no papillary lesion in three, and a nonspecific benign result in one. Excision was considered complete in 41 lesions (91%). Clinical signs of discharge were resolved in 39 patients (95% of cases treated percutaneously). Mild complications occurred in four cases.

Conclusion: Percutaneous excision of ductal lesions with an ultrasound-guided, vacuum-assisted device is a safe procedure with high diagnostic and therapeutic value for the management of breast discharge.     

3D imaging of the whole spine at 3T compared to 1.5T: initial experiences

Purpose: To describe our first experiences with a recently introduced 3T system for T2-weighted isotropic 3D whole-spine imaging.

Material and Methods: Magnetic resonance imaging of the whole spine was performed by implementing an isotropic 3D fast spin-echo sequence with variable flip-angle refocusing pulses at 3T and 1.5T. Signal-to-noise ratio (SNR) was compared on both systems in eight subjects.

Results: Mean values for SNR were significantly higher at 3T (346±214) for 1.0 mm voxel size compared to 1.5T (202±41), but showed considerably higher variability at 3T. At 3T, measurements with 0.9 mm voxel size were possible with similar SNR as with 1.0 mm voxel size at 1.5T.

Conclusion: High-resolution 3D imaging of the whole spine is feasible at 3T with an increased SNR compared to 1.5T. Signal gain at 3T can be used to further increase spatial resolution. Pronounced interpatient variability of SNR at 3T may be a result of inhomogeneous RF deposition due to dielectric effects.     

Diffusion-weighted magnetic resonance imaging of cerebrospinal fluid in patients with and without communicating hydrocephalus

Background: Recent concepts about cerebrospinal fluid (CSF) circulation in communicating hydrocephalus (CoHy), which is also termed “restricted arterial pulsation hydrocephalus,” suggest reduced arterial pulsations of subarachnoid vessels with a smaller amount of CSF shifted in subarachnoid spaces during the early systole. The postulated restriction of subarachnoid arterial pulsations in CoHy should induce a smaller motion artifact and reduced local stream effects in CSF in magnetic resonance (MR) diffusion-weighted imaging (DWI).

Purpose: To investigate the maximum diffusivity in CSF in patients with and without CoHy using DWI.

Material and Methods: 12 patients without CSF circulation disturbances and six cases with proven CoHy were assessed. Diffusion was measured in six noncollinear directions without triggering the arterial pulse wave (scan time 6:45 min, voxel size 2×2×2 mm). Due to expected artifacts, the calculated maximum diffusivity was called apparent diffusivity. Regional high and low apparent diffusivity was assessed in CSF spaces on newly created 3D CSF motion maps.

Results: Patients with regular CSF circulation exhibited high apparent diffusivity in CSF in basal subarachnoid spaces, whereas apparent diffusivity was low there in patients with CoHy.

Conclusion: DWI opens a feasible approach to study CSF motion in the neurocranium. Restricted arterial pulsations seem to be involved in CoHy.     

Pulmonary artery diameters measured by multidetector-row computed tomography in healthy adults

Background: The range of the diameters of pulmonary arteries (PA) is not fully shown in the current literature. Contrast-enhanced computed tomography (CT) of the thorax might be used for measuring diameters of the PA.

Purpose: To determine the diameters of PAs in subjects with normal PA pressure by using thoracic CT.

Material and Methods: 126 subjects aged between 19 and 46 years, having normal thoracic CTs (5-mm slice thickness) and normal PA pressures (≤25 mmHg, determined by echocardiography), were included in the study. The diameters of the main, right, and left PAs were measured by using multidetector CT.

Results: The main PA diameters of all the subjects showed a normal distribution, and the mean was 24.0±2.8 mm. The main PA diameters in male and female subjects also showed a normal distribution. The difference between the sexes for the main PA diameters was not significant (P = 0.08). There were correlations between main PA diameter and body-mass index (BMI) (R = 0.41, P = 0.001) and weight (R = 0.34, P = 0.001). However, there was no significant correlation between main PA diameter and height (R = 0.05, P = 0.6).

Conclusion: This study suggests that diameters of the main PA and its main branches show a normal distribution in subjects having normal PA pressures. Based on our findings, the upper limits of the main, right, and left PA diameters are 29.5 mm, 19.8 mm, and 22.1 mm, respectively, in healthy adults.     

Clinical 1H magnetic resonance spectroscopy of brain metastases at 1.5T and 3T

Purpose: To investigate whether improvements in signal-to-noise ratio (SNR) and spectral resolution are found in spectra from patients with brain metastases obtained at higher magnetic field strengths using standard clinical instrumentation.

Material and Methods: Six patients with brain metastases, 13 healthy volunteers, and a phantom containing brain metabolites were examined using two clinical MR instruments operating at 1.5T (Siemens) and 3T (Philips) with standard clinical head coils. Spectra were obtained using a point resolved spectroscopy pulse sequence, echo times (TE) 32 ms and 144 ms, and repetition time 2000 ms from a volume-of-interest (VOI) of size 15×15×15 mm³. SNR and spectral resolution of the metabolites N-acetylaspartate, choline, and creatine compounds in spectra from 3T were compared to the 1.5T spectra.

Results: In general, spectral resolution was improved by 25-30% at higher magnetic field strength. Only minor improvements in SNR were obtained at 3T using short echo time and 20-50% at long echo time.

Conclusion: SNR and spectral resolution were improved at higher magnetic field strength, especially with TE 144 ms, including spectra from patients with heterogeneous brain tumors. However, differences in the defined effective VOI, particularly at short echo time, reduced the expected effect of increased magnetic field strength on the measured SNR.     

Treatment of acute ischemic brain infarction with the assistance of local intraarterial thrombolysis with recombinant tissue-type plasminogen activator

Background: Cerebral infarction is usually due to arterial occlusion. Prompt treatment with thrombolytic drugs can restore blood flow and improve recovery from an infarct.

Purpose: To evaluate the clinical efficacy and safety of local intraarterial thrombolysis with recombinant tissue-type plasminogen activator (rtPA) in patients with acute middle cerebral artery (MCA) infarctions within 6 hours of the onset of symptoms.

Material and Methods: Sixteen patients (10 females and six males) aged from 42 to 61 years, with acute MCA territory infarcts were selected for treatment with local i.a. rtPA up to 6 hours after the onset of symptoms. Patient selection was based on clinical examination, computed tomography (CT), and digital subtraction angiography (DSA). A clinical evaluation was performed before treatment, at the time of discharge, and 90 days post-procedure on the basis of modified Rankin and NIHSS scores. Controls (n = 16, nine females and seven males) aged from 51 to 70 years were treated only with intravenous anticoagulation using i.v. heparin infusion. The control group was evaluated with multidetector CT (MDCT) angiography performed on entry to the study and at 2-4 hours afterwards.

Results: Eight patients (50%) achieved a modified Rankin score of 2 or less as the primary outcome after 90 days follow-up. The secondary clinical outcome at 90-day follow-up was as follows: NIHSS score ≤1, three (19%) of the patients; NIHSS score ≥50% decrease, nine (56%) of the patients. A recanalization rate of 75% was achieved in 12 of the 16 treated patients, but only 12.5% in two of the 16 patients in the control group. Intracerebral hemorrhage occurred in two (12.5%) of the patients in the treatment group, but in only one patient (6%) in the control group. There were no deaths in the treated group after thrombolysis up to the time of discharge; however, during the 90-day follow-up, two patients died compared to three patients in the control group (19% vs. 12.5% mortality rate).

Conclusion: Patients with cerebral infarction who were treated within 6 hours of onset using intraarterial rtPA thrombolysis had a significantly improved clinical outcome 90 days after the procedure compared to patients treated only with intravenous anticoagulation.     

Needle tract seeding after vacuum-assisted breast biopsy

Background: A matter of substantial concern regarding all needle biopsy techniques is seeding along the biopsy needle tract.

Purpose: To assess cell seeding along the needle tract of vacuum-assisted breast biopsy (VABB).

Material and Methods: The study included 21 patients with ductal carcinoma in situ (DCIS) and 10 patients with invasive ductal carcinoma (IDC) diagnosed by VABB for nonpalpable mammographic lesions. VABB (11G, on a Fischer table) was performed, and the duration of the procedure was measured. After surgery, the whole needle tract was embedded in paraffin blocks, stained with hematoxylin-eosin, and examined by a pathologist.

Results: Cases with dissemination of cancer cells in the needle tract were not observed (one-sided 97.5% CI 0-10.0%). In 2/31 (6.5%) cases (95% CI 0.8-21.4%), benign epithelial cell displacement was observed, and the duration of VABB was significantly longer in these two cases (52.5±3.5 min vs. 42.0±4.4 min for cases without benign cell displacement; P = 0.018, Mann-Whitney-Wilcoxon test for independent samples).

Conclusion: No displacement of malignant cells within the 11G needle tract was documented. Benign cell displacement was associated with longer VABB duration. The phenomenon of tumor cell dissemination along the needle tract is of questionable clinical significance when the treatment guidelines are followed.     

Magnetic resonance elastography of the human brain: a preliminary study

Purpose: To study the application of magnetic resonance elastography (MRE) in the human brain.

Material and Methods: An external force actuator was developed, which produced propagating shear waves in brain tissue. A modified phase-contrast gradient-echo sequence was developed. The propagating shear waves within the brain were directly imaged. The wave images were processed to obtain the elasticity image. Shear waves at 100 Hz, 150 Hz, and 200 Hz were applied.

Results: The propagating shear waves in the brain were visualized on wave images. The elasticity image revealed the difference in tissue elasticity between gray and white matter of the brain.

Conclusion: MRE could be an imaging technique for assessing the elasticity of brain tissue.     

Angulation, length, and morphology of the styloid process of the temporal bone analyzed by multidetector computed tomography

Purpose: To investigate the angulation, length, and structural variations of the styloid process (SP) by multidetector computed tomography (MDCT).

Material and Methods: MDCT scans were performed in 283 cases (127 M and 156 F, age range 18-77 years). The length of the SP and its angulation on the transverse and sagittal planes were measured. Structural variations of the SP were observed by means of three-dimensional (3D) and multiplanar reconstruction (MPR) images.

Results: The length of the bony SP on both sides varied from 0 to 62 mm (mean 26.8±10.0 mm). Angulation ranged between 55° and 90.5° (7 2.7±6.6) in the transversal plane and between 76° and 110° (93.5±6.9) in the sagittal plane. Morphologically, the SP showed a considerable amount of variation. A solitary SP was present in 168 individuals (59.4%). In 9 individuals (3.1%), the SP was duplicated (4 unilateral and 5 bilateral). Sixty-one persons (21.6%) showed an incomplete ossified SP (42 unilateral and 19 bilateral), whereas in 7 individuals (2.5%) a bony SP was absent entirely (7 unilateral). In 38 individuals (13.4%), the stylohyoid ligament was ossified (16 entirely, 22 partial). In all individuals, 3D and MPR images showed the SP in its entire length.

Conclusion: MDCT with 3D CT and MPR of SP may show further detailed information related to SP. Not only the length of the SP, but also its 3D orientation, should be in focus in anatomical and clinical studies.     

Radiological contrast media and pancreatic blood perfusion in anesthetized rats

Background: Radiological contrast media (CM) have been suggested to be able to impair pancreatic microcirculation.

Purpose: To evaluate the effects of an iso-osmolar (iodixanol, 290 mOsm/kg H₂O) and a low-osmolar (iopromide, 660 mOsm/kg H₂O) CM on total pancreatic and islet blood perfusion.

Material and Methods: Thiobutabarbital-anesthetized rats were injected with iodine-equivalent doses (600 mg I/kg body weight) of iodixanol or iopromide. Saline or low-osmolar mannitol (660 mOsm/kg H₂O) solutions served as control substances. Blood perfusion measurements were then carried out with a microsphere technique.

Results: Iso-osmolar iodixanol had no effects on blood perfusion. Low-osmolar iopromide increased total pancreatic blood perfusion, whereas islet blood perfusion was unchanged. No differences were seen when mannitol solutions were given.

Conclusion: Neither an iso-osmolar nor a low-osmolar CM affected pancreatic islet blood perfusion, whereas the low-osmolar CM increased total pancreatic blood perfusion. The absence of hemodynamic effect of low-osmolar mannitol suggests that the hyperosmolality per se of iopromide versus iodixanol does not induce the hemodynamic effect. The consequences of the effect of iopromide for pancreatic function remain to be established.     

Impact of digital imaging on radiation doses to the patient during X-ray examination of the urinary tract

Purpose: To compare radiation doses given to patients undergoing IVU (intravenous urography) before and after digitalization of our X-ray department.

Material and Methods: IVU examinations were monitored with dose area product meters before and after the X-ray department changed to digital techniques. The first step was a change from film-screen to storage phosphor plates, while the second step involved changing to a flat panel detector. Forty-two patients were included for the film-screen situation, 69 when using the storage phosphor plates, and 70 using the flat panel detector.

Results: A dose reduction from 41.8 Gycm² to 31.5 Gycm² was achieved with the first step when the film-screen system was replaced with storage phosphor plates. A further reduction to 12.1 Gycm² was achieved using the flat panel detector.

Conclusion: The introduction of the flat panel detectors made a considerable dose reduction possible.