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Background Dual-energy digital radiography (DEDR) has been shown to be a potential method to determine bone mineral density (BMD) and predict maximal load with similar accuracy as standard bone densitometry using DXA (dual-energy X-ray absorptiometry). In addition to bone density, bone geometry has also been shown to have effect on bone fragility and fracture risk. Purpose To examine the combination of BMD and geometry parameters, as determined from a DEDR experiment, to predict bone maximal load. Material and Methods Reindeer femora ( n = 47) were imaged at two energies (79 kVp and 100 kVp) using a clinical digital radiography system. BMD was determined in four regions from these images using the DXA calculation principle. Various geometrical parameters were determined from the 79 kVp image. Femora were mechanically tested using axial loading configuration. Pearson correlation coefficients were determined between geometrical parameters and BMDs or maximal load. Multiple stepwise linear regression analysis was used to find the best combination to predict bone maximal load. Results From the geometrical parameters, femoral shaft diameter (FSD) and femoral neck axis length (FNAL) correlated best with the maximal load ( r = 0.629 and r = 0.446, P < 0.01, respectively). The best combination of parameters to predict bone fragility was BMD at Ward's triangle, FSD and FNAL ( r = 0.787, P < 0.05), whereas the correlation coefficient between BMD at Ward's triangle and maximal load was 0.653 ( P < 0.05). Conclusion The combination of DEDR-based BMD and geometrical parameters predicts reindeer bone maximal load with reasonable accuracy and the combined analysis improves the prediction of maximal load compared to BMD prediction only.

Background: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. Purpose: To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. Material and Methods: In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. Results: MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. Conclusion: After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.

Background: Bone mineral density (BMD) is usually determined by dual-energy X-ray absorptiometry (DXA). Digital radiography (DR) has enabled the application of dual-energy techniques for separating bone and soft tissue, but it is not clear yet whether BMD information can reliably be obtained using DR. Purpose: To determine the ability of dual-energy digital radiography (DEDR) to predict BMD as determined by DXA. Material and Methods: Reindeer femora ( n=15) were imaged in a water bath at a typical clinical imaging voltage of 79 kVp and additionally at 100 kVp on a DR system. BMD was determined in four segmented regions (femoral neck, trochanter, inter-trochanter, Ward's triangle) from these images using the DXA calculation principle. BMD results as determined by DEDR were compared with BMD values as determined by DXA. Results: Significant moderate to high linear correlations (0.66–0.76) were observed at the femoral neck, Ward's triangle, and trochanter between BMD values as determined by the two techniques. The coefficient of variation (CVRMS) ranged between 2.2 and 4.7% and 0.2 and 1.8% for DEDR and DXA analyses, respectively. Conclusion: DXA-based BMD information can be obtained with moderate precision and accuracy using DEDR. In future, combining BMD measurements using DEDR with structural and geometrical information available on digital radiographs could enable a more comprehensive assessment of bone.

Purpose: To describe the in vivo appearance of magnetic resonance imaging (MRI) diskograms of normal and degenerated lumbar intervertebral disks, and to evaluate the differences in imaging findings between sequential diagnostic MRI and MRI diskography. Material and Methods: Nine consecutive patients underwent MRI-guided diskography in order to determine possible pain provocation during puncture and contrast medium injection. All patients had preceding clinical suspicion of lumbar diskogenic pain and findings of lumbar disk degeneration in diagnostic (MRI, computed tomography (CT), plain radiography). A 0.23T open MRI scanner with interventional tools was used for imaging and instrument guidance. On all patients, a complementary diagnostic MRI study of the lumbar spine before and after the MRI-guided disk injection was performed, and subsequent axial MRI diskograms were obtained. Results: A total of 25 disk punctures were initialized, and 25 MRI diskograms were obtained and their expression described. There was a correlation between the degenerative disk findings visualized by diagnostic MRI and MRI diskograms. Conclusion: The use of gadolinium contrast media in MRI-guided diskography enables the evaluation of MRI diskograms. Our results suggest that MRI-guided diskography can be used to substitute conventional diskography or CT-diskography and as an augmenting method to assess diagnostic information upon degenerative processes of the lumbar spine.

Purpose: To assess the suitability of apparent diffusion coefficient (ADC) measurements to evaluate degeneration processes of the vertebral disc and to compare the results with T2 relaxation time measurements in both degenerated and normal intervertebral discs. Material and Methods: Fourteen young patients (8.8-20.8 years old) who had had a vertebral compression fracture at least 1 year earlier, underwent MR studies with diffusion imaging in three orthogonal directions and T2 relaxation time measurements. ADC values and T2 relaxation times of both degenerated and normal intervertebral discs were compared to the values of 20 healthy young asymptomatic control subjects. Results: In the degenerated discs of patients, the ADCx and ADCy values were decreased compared to earlier determined values of healthy controls. ADC values in the z-direction in degenerated discs did not differ significantly from the values of controls. T2 relaxation times were shorter in the degenerated discs of patients compared to the values of controls. The greatest changes in both these values were observed in degenerated discs followed by discs with normal signal intensity adjacent to primary trauma area and secondary trauma area. Conclusion: We suggest that decreased ADC values reflect the lost integrity of the intervertebral disc. ADC measurements at MR may prove sensitive depicting of early degenerative changes in vertebral discs.

Purpose: To evaluate the ability of US and MR cholangiography (MRC) to detect bile duct changes and prognostic signs of primary sclerosing cholangitis (PSC) seen at endoscopic retrograde cholangiography (ERC). Material and Methods: In a prospective study, 9 patients with PSC underwent US, MRC, MR imaging and ERC of the bile ducts and the liver. Eight age- and sex-matched control patients were examined with MRC, MR imaging and ERC. A segmental comparison was performed to assess the ability of MRC-MR and US to reveal the accurate ductal involvement in different segments of the biliary tree and the specific criteria of poor prognostic outcome in PSC. The ability of MRC-MR to detect the presence of PSC in different patients was analysed blindly. Results: MRC-MR depicted changes of PSC correctly in 9 patients (radiologist 1) and in 8 patients with 1 false-positive finding (radiologist 2) in the blinded analysis. In the segmental comparison, MRC missed especially bile duct dilatations. MRC was too pessimistic in the evaluation of the outcome. US detected features suggestive of PSC in 8 patients (radiologist 3). US was unable to show the predictors of poor outcome. Conclusion: MRC and US seem to be useful in the detection of PSC. US is unable and MRC is too pessimistic to estimate the outcome of PSC.

Objective: To study the efficacy of continuous quality improvement (CQI) compared to ordinary management in an on-duty radiology department. Material and Methods: Because of complaints regarding delivery of on-duty radiological services, an improvement was initiated simultaneously at two hospitals, at the HUCH (Helsinki University Central Hospital) utilising the CQI-method, and at the OUH (Oulu University Hospital) with a traditional management process. For the CQI project, a team was formed to evaluate the process with flow-charts, cause and effect diagrams, Pareto analysis and control charts. Interventions to improve the process were based on the results of these analyses. Results: The team at the HUCH implemented the following changes: A radiologist was added to the evening shift between 15:00-22:00 and a radiographer was moved from the morning shift to 15:00-22:00. A clear improvement was achieved in the turn-around time, but in the follow-up some of the gains were lost. Only minimal changes were achieved at the OUH, where the intervention was based on traditional management processes. Conclusion: CQI was an effective method for improving the quality of performance of a radiology department compared with ordinary management methods, but some of this improvement may be subsequently lost without a continuous measurement system.

Examinations carried out on 302 consecutive patients with MR of the knee between January 1988 and March 1989 were reviewed for detection of trabecular lesion. Twenty-seven patients found presenting trabecular lesion were further reviewed with specific reference to their activity level and need for specific therapy to determine the clinical significance of the trabecular lesion. Twenty-one of the trabecular lesions were in the femur, 5 were in the tibia, and one was in the fibula. Three of them were associated with a direct trauma, 12 with a valgus type injury, 3 with pure rotation mechanism, and 5 with a combination of valgus and rotation. In 17 cases trabecular lesion was a single finding, in 10 cases it was associated with some ligamentous tear. At the follow-up visit, 26 of the 27 patients with trabecular lesion had no symptoms, and the patient with moderate knee symptoms had had similar knee symptoms prior to the accident due to an osteochondral defect. We conclude that a trabecular lesion in an MR image is a benign bone change associated with knee trauma which heals without sequelae.

Computed tomography (CT) images of 59 discs in 30 patients suffering from low back pain were compared with CT/discography images of the same discs in order to assess the correlation between intradiscal damage and changes in annular configuration and density. The discs were graded in CT as not bulging, slight protrusion, advanced protrusion or disc herniation, and were checked for local areas of hypodensity. General degeneration and annular disruption in CT/discography were evaluated separately according to the Dallas Discogram Description, on a scale of non-existent, slight, moderate, or severe. Most discs with a slight protrusion in CT showed severe annular disruption in CT/discography. Discs with advanced protrusion showed in addition a severe general degeneration. Disc herniation was associated only with severe annular disruption. Local hypodensity proved to be a specific but insensitive sign of annular disruption. It is concluded that a bulging disc is a sign of intradiscal damage and should be noted even when there is no nerve entrapment present.