Muscle magnetic resonance imaging shows distinct diagnostic patterns in Welander and tibial muscular dystrophy.

OBJECTIVES: This is a report on a retrospective muscle magnetic resonance imaging (MRI) study on 11 patients affected by Welander distal myopathy (WDM) and 22 patients with tibial muscular dystrophy (TMD) carried out in order to define the pattern and characteristics of muscle involvement. RESULTS: WDM patients showed involvement of gastrocnemius, soleus, tibial anterior (TA) and extensor digitorum longus (EDL), as well as hamstrings and hip adductor muscles. TMD patients showed involvement of the TA and EDL muscles, and in some patients also hamstring and posterior compartment muscles of the legs. Some patients showed asymmetry of muscle involvement. CONCLUSION: We conclude that muscle MRI examination proved to be very useful in the determination of the exact pattern of muscle involvement in WDM and TMD. Clinical testing using the Medical Research Council scale is not sensitive enough to establish the pattern of muscle involvement in focal muscle diseases.

Association between pleural plaques and coronary heart disease.

OBJECTIVE: The aim of this study was to verify a clinical impression that patients with coronary heart disease disproportionately frequently have calcified pleural plaques. METHODS: Chest X-rays were collected from 148 patients referred consecutively to the Helsinki University Central Hospital for coronary angiography and from 100 consecutive lung cancer patients seen at the same hospital. The radiographs were analyzed for the presence of calcified pleural plaques according to the classification the International Labour Office. A generalized linear model with binomial distribution and log link was used to estimate the relative risks and their 95% confidence intervals (95% CI). RESULTS: The prevalence of calcified pleural plaques was 35% for the coronary patients and 19% for the lung cancer patients. Calcified pleural plaques were more common among the men than the women, and the risk increased with age. The relative risk of calcified pleural plaques, adjusted for age and gender, was 2.19 (95% CI 1.44-3.32) for the coronary patients as compared with the lung cancer patients. CONCLUSIONS: Further studies with better information on past exposure to asbestos and other potential risk factors are warranted to confirm the observations and to examine whether the association between coronary heart disease and calcified pleural plaques is related to an etiologic or an individual susceptibility factor common to both of these conditions.

The efficacy of a continuous quality improvement (CQI) method in a radiological department. Comparison with non-CQI control material.

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.

Antimyosin scintigraphy compared with magnetic resonance imaging in inflammatory myopathies.

OBJECTIVE: To compare indium In 111 altumomab pentetate-labeled antimyosin scintigraphy with magnetic resonance imaging (MRI) in the diagnosis and follow-up of patients with myositis. DESIGN AND METHODS: Sixteen patients with polymyositis and 1 patient with dermatomyositis, all verified with biopsy samples, were examined during diagnostic evaluation with antimyosin antibody scintigraphy and low-field MRI of the thighs and calves using T1- and T2-weighted sequences. Both examinations were repeated 6 to 22 months after therapeutic intervention with antiinflammatory drugs. The performance of the 2 methods for the assessment of the severity of muscle inflammation was evaluated using comparison with clinical examination and the serum creatine kinase level. RESULTS: At diagnosis all patients had increased uptake of antimyosin antibody in the thighs and/or calves. In T2-weighted MRI images, increased signal intensity changes reflecting intramuscular edema and inflammation were seen in all patients in at least 1 muscle group in the thighs or calves. After anti-inflammatory drug therapy, the mean uptake of antibody and the mean signal intensity changes in T2-weighted MRI had decreased. However, in T1-weighted MRI the signal intensity changes reflecting intramuscular fatty degeneration were more pronounced in the follow-up study. The level of serum creatine kinase had decreased markedly by the second examination except in 1 patient who also had more accumulation of antibody in the calves after than before treatment. The clinical condition improved in 8 patients and remained unchanged in 9 patients. CONCLUSIONS: Antimyosin scintigraphy and T2-weighted MRI are feasible tools for the detection and follow-up of lesions in patients with myositis. Scintigraphy findings correlate with serum creatine kinase activity and seem to reflect disease activity better than T2-weighted MRI changes, whereas secondary degenerative intramuscular lesions are only detectable using T1-weighted MRI.

Magnetic resonance imaging is superior to computed tomography and ultrasonography in imaging infectious liver foci in acute leukaemia.

We conducted a prospective study in order to compare ultrasonography, computed tomography and magnetic resonance imaging in the detection of liver foci in patients with acute leukaemia and clinical suspicion of hepatic candidiasis. 28 adult patients fulfilling set entry criteria after recovery from neutropenia were studied. Lesions in the liver were detected by at least one imaging modality in 21 patients: by ultrasonography in 7 (33% of detected cases), computed tomography in 12 (57%) and by magnetic resonance imaging in 20 patients (95%). Magnetic resonance imaging was significantly more sensitive than ultrasonography (p<0.001) and computed tomography (p<0.02). The difference between computed tomography and ultrasonography was not statistically significant (p=0.1). Invasive procedures performed in 10 patients provided definite proof of candidiasis in 5 patients, and nodes on the liver surface, compatible with yeast infection, were seen during laparoscopy in 3 other patients without proof of fungal infection. We confirm that magnetic resonance imaging is superior to ultrasonography and computed tomography in imaging liver foci in leukaemic patients recovering from neutropenia with persistent non-specific signs of infection or hepatic involvement.

Low-field MR imaging for the assessment of therapy response in musculoskeletal infections.

Fifty-one patients with musculoskeletal infection were imaged by repeated MR imaging at ultra low-field and low-field strength. Soft-tissue infection, osteomyelitis, septic arthritis, and spondylitis were studied. The MR finding was scored according to the signal intensity (SI) on T2-weighted images (T2WI), and correlated with the values of serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and peripheral white blood cell (WBC) count. There was a positive correlation between the MR score and both CRP and ESR, but no correlation between MR score and WBC. The MR score between the follow-up studies decreased significantly in accordance with clinical reconstitution. The MR finding according to the SI on T2WIs corresponded better to disease activity than did the CRP or ESR.

191Os/191mIr-generator for studying arterial blood flow in experimental animal models.

Iridium-191m (191mIr, t1/2 = 4.96 sec), an ultra-short lived tracer, has turned out to be suitable for gamma imaging. It can be obtained in high yields from an 191Os/191mIr-generator with a low 191Os breakthrough. In this study the blood flow in the carotid and kidney arteries was studied in rabbits by radionuclide arteriograms. In addition, the whole body retention and biodistribution of 191Os was studied in rats. 191mIr was obtained from an activated carbon system, in a modification of the procedure described in the literature. The kidney regions (study I) of rabbits were imaged dynamically (5 frames/second) for up to 40 seconds, and the investigations were repeated 4-7 times in the same animal. Similarly, the carotid arteries were studied (study II) and from the curves flow parameters were calculated. In order to study the 191Os breakthrough two groups of rats (n = 5) were sacrificed one day and four days after injecting five diagnostic doses into the tail vein (study III). In study III the Os-retention was highest in the kidneys and spleen, followed by the muscles and liver: 0.11-0.12% ID/g tissues were obtained at 1 day and 0.10-0.13% ID/g at 4 days, respectively. These values indicate that the breakthrough values are by no means toxic and that investigations can be repeated immediately with a negligible radiation exposure. The investigations performed with the same animals (I-II) could be easily repeated and were reproducible. All of this indicates that 191mIr is suitable for radionuclide angiography and the generator system is simple and safe to use (191Os is beta-emitter).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of digital edge-enhancement on the visibility of normal parenchymal lung markings.

Digital 'conventional-like' (C-L) and edge-enhanced (E-E) posteroanterior chest roentgenograms of 42 healthy individuals were ranked twice (interval of at least 5 days) in the order of increasing lung parenchymal markings (a total of four rankings). This was done by three radiologists, two residents, one medical student and one radiographer. There was a good general consistency of rankings for both the C-L and E-E images. The correlation coefficients were best (median 0.600) (P < 0.05) between the consequent rankings of C-L images compared to the subsequent rankings of E-E images (median 0.440) and to the various combinations between the rankings of both kinds of images. Subtle differences in normal lung parenchyma could, therefore, generally (five of the seven observers) best be demonstrated in C-L images, but two observers managed best with the E-E images.

Quality assurance of the bedside chest radiography process.

The bedside chest radiography process was analyzed in terms of modern quality management guidelines and the sources of quality problems were identified. In order to analyze systematically the various quality factors, the process was described in a top-down fashion with the aid of data flow diagrams. Two internal quality control points and one external point were found in the process. Means to measure quality at the quality control points including questionnaires and a formula for calculating the internal quality index were developed.

Improvement of bedside chest radiograph quality using a high ratio grid and an electronic angle meter for alignment.

An electronic level was used to ensure proper alignment of a high ratio grid at bedside chest radiography. The image quality was clearly improved. The method is inexpensive and simple to use.

T1 rho dispersion imaging of diseased muscle tissue.

T1 rho dispersion, or the frequency dependence of T1 relaxation in the rotating frame, was used for in vivo muscle tissue characterization in 13 patients with primary skeletal muscle disease and in eight normal subjects for comparison. T1 rho dispersion measurements represent a new approach to magnetic resonance tissue characterization, possibly reflecting the macromolecular constituents of tissue. A definite, statistically significant, difference was found between the relative T1 rho dispersion values of normal and diseased muscle tissue. T1 rho dispersion measurements and images may increase the accuracy of identification of diseased muscles. Early identification of affected muscles is important for accurate diagnosis by muscle biopsy.

Observed lung markings in normal chest roentgenograms.

The digital chest posterior-anterior roentgenograms of 42 healthy individuals were ranked twice (interval of at least 5 days) in the order of increasing lung parenchymal markings. The evaluations were made by three radiologists, two residents, a medical student and a radiographer. All observers regardless of their radiological experience showed good intraobserver correlations between their two subsequent rankings (p < 0.05-0.001). The interobserver agreement on rankings was generally poor, even if the radiologists were considered. Radiologic training seemed to eliminate the influence of false leading factors (the object's respiration and body constitution). "The golden standard of evaluation" (= the added-up rankings by the radiologists) did not correlate either with the patient's ages (19-54 years) or smoking habits (0-45 pack-years, mean 4.2).

The effect of digital unsharp-mask filtering on the signal-to-noise ratio in computed radiography.

The effect of image processing in computed radiography (CR) has been analyzed in many ROC studies. The results have not shown great diagnostic improvements, except in some special occasions. The theoretical effect of image enhancement on the signal-to-noise ratio in CR images has so far not been assessed. Concerning the previous results, the changes induced in the signal-to-noise ratio by digital image processing are certainly of interest. We calculated the signal-to-noise ratio in various conditions according to the principles of the Rose model, using the computerized image data of storage phosphor radiography. Seventy-seven computed radiographs processed by Gaussian unsharp-mask filtering using different kernel widths were analyzed. The signal-to-noise ratio was reduced in all images by more than 40% when the smallest kernels were used, and increased slowly towards the original value with greater kernel sizes. In no conditions did the ratio exceed the original one. The results show that although edges and signal contrast can be enhanced by unsharp-mask filtering, this happens at the cost of increased noise. This might at least in part explain why image processing does not significantly improve the diagnostic information content of a computed radiograph.

Computed radiography and image workstation from the radiologist's point of view.

A computed radiography system (Digiscan, Siemens) connected to an image workstation (Siemens) has been used for 1 1/2 years in our department. The image quality is good and it has been possible to reduce radiation dose by about 30% without any appreciable loss of image quality. The image workstation has been used in cases where image postprocessing is considered to be useful. For routine reporting of X-ray images the workstation is too slow although the image quality is comparable to that of the computed radiography film.

The scatter-to-primary ratio as a function of varying X-ray absorption measured by computed radiography.

Some scatter studies have previously been conducted using film as a detector. The serious limitations caused by the narrow latitude, the non-linear density response, and the required optical densitometric measurements of film can be avoided by computed radiography (CR) which provides linear numeric data over a wide dynamic range. The imaging plate is used as a large-area detector and the data is analyzed from the computer memory. Variation in the scatter-to-primary ratio within an image caused by absorption differences was simulated in a water-aluminum phantom. The measurement technique showed repeatable results, being comparable to the values expected on the basis of previous studies. A multiple pencil-beam (MPB) imaging device was also compared to a standard 1:12 grid by this technique. The maximal scatter-to-primary ratio in our model was up to 7.9 with no scatter reduction, 1.5 with grid, and 0.4 with the MPB device. The variation caused by the absorption of primary radiation was much less in the MPB modality, and the MPB system was also less sensitive to an increase in the used tube voltage from 60 to 120 kVp. The benefits of multiple pencil-beam imaging in scatter reduction are briefly discussed.

Combination of multiple pencil-beam imaging to computed storage phosphor radiography: a new method.

Computed radiography (CR) with storage phosphors offers a wide dynamic range and improved sensitivity compared to film-screen technology. CR was combined in this study with a prototype multiple pencil-beam (MPB) imaging device which has been shown to be very effective in scatter reduction. The combination was analyzed and compared to the standard technique of grid screening in two ways: a free-response ROC (FROC) analysis was first performed followed by a blinded test arrangement for visual analysis of image quality in a series of computed radiography of the lumbar spine by both the MPB and grid modalities. The results of the FROC study showed a statistically significant (P less than or equal to 0.01) improvement in signal detection. The MPB-CR images of the lumbar spine had more contrast but also a slightly mottled or grainy appearance. Image quality was found good but contrast processing was criticized because it seemed to result in a too steep display of contrast in MPB imaging. This should be avoidable by changing the image processing parameters.

The effect of scatter reduction on the signal-to-noise ratio in computed radiography.

Signal-to-noise ratio (SNR) in computed radiography (CR) was assessed by using the computerized image data from storage phosphor radiographs in a modification of the Rose model. A multiple pencil-beam (MPB) imaging device, a conventional 1:12 grid, and an air gap of 90 cm were compared in terms of improvement of the signal-to-noise ratio caused by the reduction of scatter. The MPB device showed better SNRs by a factor of 1.25 compared to the grid and air gap which were approximately equal to each other. This is related to its superiority in scatter control, which has also been shown previously. Air gap screening has not been very popular because of geometrical problems, but in scatter reduction it is still comparable to today's grid technology. The optimization of image information content in CR is briefly discussed.

Detection of soft-tissue and skeletal infections with ultra low-field (0.02 T) MR imaging.

To evaluate the use of ultra low-field (0.02 T) magnetic resonance (MR) imaging in the diagnosis of musculoskeletal infection, MR examinations with T2 weighted sequences were performed in 61 patients thought to be suffering from one of four major diagnostic categories: Soft-tissue abscesses (n = 22), osteomyelitis (n = 21), septic arthritis (n = 9) and spondylitis (n = 9). Infection was confirmed for 37 of these 61 patients. The verified abscesses, arthritis, spondylitis and acute osteomyelitis could be detected by 0.02 T MR. The sensitivity was poor in cases of chronic osteomyelitis. There was one false positive finding in a patient with a possible soft tissue infection. The 0.02 T MR examination failed four times. Two patients were too heavy and another 2 patients had magnetic material in or near the scanning field. Compared with computed tomography and isotope scanning, 0.02 T MR proved a little more informative, but without any statistical significance.