Biomedical subjects

T Vehmas

Publications and source records attributed to T Vehmas.

At least 37 records · Page 2Linked to original sources

PubMed2001

Endorectal magnetic resonance imaging of prostatic cancer: comparison between fat-suppressed T2-weighted fast spin echo and three-dimensional dual-echo, steady-state sequences.

The aim of this study was to develop an endorectal MRI strategy for prostatic cancer. We evaluated the MR images from 44 consecutive prostatic cancer patients treated by radical prostatectomy. Each sequence from every examination was assessed separately with a specific tumor map drawn. Tumor localization, capsular penetration, and seminal vesicle invasion were marked on maps on the basis of T2 and DESS (dual-echo steady-state) sequences. Thirty patients also had T1-weighted images, and these were assessed with regard to possible tumor outgrowth. The maps were compared with histopathological findings from radical prostatectomy specimens. According to our study, DESS equaled T2 in every respect. No statistically significant differences between the sequences were found with respect to detecting either tumor localization, outgrowth, or seminal vesicle invasion. DESS is a potential new sequence in prostatic MRI as it has been proven to parallel the routinely used T2-weighted imaging.

Aged↗

PubMed2001

Optimal timing of post-biopsy MR imaging of the prostate.

PURPOSE: To assess the quantity and frequency of hemorrhage after prostatic biopsy. As post-biopsy blood products may interfere with interpretation of MR images, we also investigated the optimal timing for MR examination after biopsy. MATERIAL AND METHODS: Fifteen patients scheduled for prostatic biopsies were imaged with endorectal MR before and after the procedure. In addition, MR studies of 42 patients with prostate cancer were retrospectively analyzed. The amount of post-biopsy blood product and the degree of its interference with image interpretation were assessed. RESULTS: Of a total of 57 patients, 44 (77%) had visible post-biopsy hemorrhage. However, the presence of blood products were considered to interfere with interpretation of the images in only 12 (21%) cases. This disturbing effect seems to diminish after 21 days from biopsy. The total amount of blood clearly decreased after 28 days. CONCLUSION: Deferring MR imaging for at least 3 weeks after prostatic biopsy is advisable. T1-weighted images are necessary to rule out false-positive findings caused by post-biopsy hemorrhage.

Aged↗

PubMed2001

Estimation or quantification of tumour volume? CT study on irregular phantoms.

PURPOSE: To compare radiologists' subjective size estimation to computerised volume quantification of tumour-like phantoms in spiral CT. MATERIAL AND METHODS: Eight tubular phantoms with the inside irregularly covered with silicone (8.7-31.6 ml) were imaged. The phantoms were pairwise compared to analyse the differences in silicone volumes. The observers, 2 radiologists and 2 residents, used both subjective image analysis (2 sessions) and computerised volume quantification (1 session). Accuracy and observer agreement of both methods were calculated. RESULTS: Subjective size estimation was correct in 51% (mean weighted kappa, Kqw=0.73). Using four observers' mean value (Kqw=0.81) or median value (Kqw=0.77) slightly improved the results. Average intra-observer agreement was better than average interobserver agreement. In computerised volume quantification 70% of all classifications were correct (mean Kqw=0.85). The results were moderate even when every second or fourth slice were measured. CONCLUSION: Subjective size estimation of irregular tumours should be repeatedly performed by the same observer, or by using the mean or median estimate of several observers. Computer-based methods are even more reliable and their use is especially recommended for film readers with limited radiological experience. Only every fourth slice may be measured without a major loss of measurement accuracy.

Humans↗

PubMed2001

Prostatic MR imaging. Accuracy in differentiating cancer from other prostatic disorders.

PURPOSE: We assessed the accuracy of MR imaging in differentiating between cancer and other prostatic disorders, and evaluated the diagnostic criteria for various prostatic diseases. MATERIAL AND METHODS: A total of 74 endorectal coil MR studies were performed on 72 patients. Twenty patients had prostatic cancer, 20 benign prostatic hyperplasia (BPH), 4 acute bacterial prostatitis, 5 chronic bacterial prostatitis (2 also belonging to the previous category), 19 chronic non-bacterial prostatitis/chronic pelvic pain syndrome, and 6 were symptomless voluntary controls. All studies were interpreted by two experienced radiologists in random order. Radiologists were blinded to all clinical data including the age of the patients. Based on MR findings, both radiologists filled in a form covering diagnostic criteria and diagnosis. RESULTS: Accuracy in diagnosing prostate cancer was 74%. Sensitivity was 50% and specificity 83%, and positive and negative predictive values were 53 and 82%, respectively. Bacterial prostatitis showed some features similar to carcinoma. Abundant BPH rendered cancer detection more difficult. No diagnostic criterion was clearly better than the others. Interobserver agreement on the MR diagnosis ranged from moderate to good. CONCLUSION: Without knowledge of accurate clinical data, MR seems to be too insensitive in detecting prostate cancer to be used as a primary diagnostic tool.

Aged↗

PubMed2001

MR findings in humeral epicondylitis. A systematic review.

PURPOSE: To highlight the importance of meta-analysis in diagnostic imaging by presenting a systematic search of the literature on the accuracy of MR imaging in epicondylitis. MATERIAL AND METHODS: The literature was comprehensively reviewed to identify studies on MR findings in epicondylitis. Reviewers blind to the clinical diagnoses screened the data according to predetermined inclusion criteria. Data were collected and validity and relevance were assessed on structured forms. RESULTS: Seven studies including 148 patients with epicondylitis were accepted for the analysis. Eleven asymptomatic contralateral elbows and 29 elbows of healthy volunteers served as controls. The volunteers were distinctly younger than the patients. The MR technique was divergent, and the observed pathological changes also varied. The most frequent alteration was a change in the common extensor tendon signal (90%, 95% confidence interval 84-94%); 14% of the healthy volunteers and 50% of the contralateral elbows displayed the similar alteration. CONCLUSION: Small sample size and methodological shortcomings in the original studies make the assessment of MR findings in epicondylitis questionable. There is a need for well-designed studies in which clinical features and occupational backgrounds as well as imaging parameters are carefully documented.

Adult↗

PubMed2001

Influence of radiologists' sex and training on fluoroscopy doses during barium enema.

Variables influencing radiation exposure were studied using analysis of covariance in 523 double contrast barium enemas performed by 21 radiology residents (12 female, 9 male). Dose-area products (DAPs) (ns), number of exposures per patient (p < 0.05) and screening times (p < 0.05) were higher for female residents (mean 52.0 Gy cm2, 9.55 exposures and 4.02 min, respectively) than for male residents (mean 41.7 Gy cm2, 8.26 exposures and 3.20 min, respectively). The number of lectures on radiation protection attended by the resident (range 0-20) had no significant effect on these radiation-related variables. Other factors explaining these variables were patient age, diagnosis and anteroposterior thickness. Radiologists' use of ionizing radiation during fluoroscopy may be sex-related. Traditional lecture-based education on radiation protection was not effective with this group; thus, improved methods should be developed to control doses.

Adult↗

PubMed2001

High-resolution computed tomography classification of lung fibrosis for patients with asbestos-related disease.

OBJECTIVES: This study tested a new high-resolution computed tomography (HRCT) scoring method for asbestos-induced parenchymal changes in the lung. METHODS: HRCT scans of 602 asbestos-exposed workers and 49 referents were reviewed by 3 radiologists. Structured forms were filled out for a semiquantitative HRCT fibrosis score based on several specified parenchymal abnormalities scored separately. Observer agreement was studied with the use of the quadratic-weighted kappa (kappaqw). The HRCT fibrosis score (from 0 to V with definitions and index images given retrospectively) was compared with the radiographic classification of the International Labour Office (ILO) for the same patients. Receiver-operating characteristic (ROC) curves were computed to compare the tests for diagnosing asbestosis. RESULTS: Good inter- and intraobserver agreements were achieved (kappaqw = 0.64 and 0.72, respectively) as regards the HRCT fibrosis score. All the specified computed tomography findings explained 86% of the variance in the HRCT fibrosis score. Age and occupational group were significant predictors of fibrosis. The area under the ROC curve was significantly greater for the HRCT fibrosis score (0.89) than for the ILO radiographic classification (0.76). The sensitivity (70%) and specificity (91%) of the HRCT fibrosis score (classes I/II-V representing asbestosis) were better than those of the classification published by the International Labour Office (51% and 89%, respectively, score > or = 1/0 representing asbestosis). CONCLUSIONS: The examined HRCT scoring method proved to be a simple, reliable, and reproducible method for classifying lung fibrosis and diagnosing asbestosis also in large populations with occupational disease, and it would be possible to use it as a part of an international classification.

Adult↗

PubMed2000

Magnetic resonance imaging of prostatic cancer: does detection vary between high and low gleason score tumors?

BACKGROUND: Both Gleason score and prostate-specific antigen (PSA) concentration are prognostic factors for prostate cancer. We assessed our ability to localize cancer lesions based on Gleason scores and PSA values by endorectal coil magnetic resonance imaging (MRI). We also evaluated whether the size of the prostate affects tumor detectability. METHODS: We compared the findings of MRI and histopathological results of radical prostatectomy specimens from 63 patients; they were divided into four groups, based on Gleason score and also on serum PSA concentration. Furthermore, the possible effect of prostatectomy specimen weight on MRI interpretation was examined. RESULTS: A highly significant difference appeared in detection of cancer lesions based on their differentiation grade. No statistically significant difference existed between PSA groups in detection of tumors, but the large size of the prostate seemed to render image interpretation more difficult. CONCLUSIONS: Endorectal MRI detects poorly differentiated prostate cancer lesions more accurately than clinically insignificant tumors.

Aged↗

PubMed2000

Factors influencing patient radiation doses from barium enema examinations.

PURPOSE: To analyse factors behind the variation of patient doses from barium enema (BE) examinations. MATERIAL AND METHODS: The patients' (n=89) organ and effective doses (E) due to BE examinations were computed with the ODS-60 program. An average risk factor for BE examinations was derived using the BEIR V schema. The correlation of E with several independent variables was analysed. RESULTS: Median Es at five hospitals were 4.4, 6.1, 7.1, 13 and 16 mSv. The E of the female patients (median 9.2 mSv) was higher than that of the males (median 5.4 mSv) (p<0.001) due to the higher female doses to the gonads, bladder and uterus, resulting from different body structure. An average fatal risk factor of 0.02%. per one BE examination was derived. Factors controlled by the radiologist (screening time, number of exposures) explained 40% and patient-related factors explained 16% of the total variation of E. The equipment-related factors are included in the residual 44%. CONCLUSION: Due to the large contribution of the radiologists' examination technique in the value of E, an optimal examination technique is essential in reducing doses and the stochastic risk to patients.

Adult↗

PubMed2000

Seasonal variation in the occurrence of late adverse skin reactions to iodine-based contrast media.

PURPOSE: To study the possible seasonal effect in the occurrence of late adverse skin reactions to iodine-based contrast media (CM). MATERIAL AND METHODS: Data on 4,875 adult patients followed for late adverse reactions after i.v. injections of iohexol or iopamidol, or intra-arterial injection of ioxaglate were retrospectively investigated with respect to the amount of global radiation vs. the occurrence of reactions. The information on these reactions was collected from questionnaires that were filled out by the patients (out-patients) or by nurses (in-patients). The follow-up time was 24 h. RESULTS: Fifty-two of 4,875 patients (1.07%) had experienced a late skin reaction (urticaria or rash); this number exceeds the reports on spontaneous occurrence of such reactions by a factor of 300. Most of the reactions in a known location occurred on sun-exposed areas of the body. A 2-month peak in the incidence of reactions (May to June) included 35% of all events (p<0.025) and a 3-month peak (April to June) 46% of all events (p<0.01). There was a significant rank correlation (r = 0.613, p<0.05) between the frequency of reactions and the mean amount of global radiation. CONCLUSION: This study demonstrates a seasonal variation in skin reactions after intravascular injection of iodine-based CM. The possible photosensitising effect of these drugs should be further studied.

Adolescent↗

PubMed2000

Lung sounds in asbestos induced pulmonary disorders.

The aim of the study was to compare the lung sounds in patients with asbestos related pulmonary disorders with findings in high-resolution computed tomography (HRCT), and with lung function variables, in order to find out associations of acoustic changes with radiological fibrosis, emphysema or with pulmonary gas transfer functions. Sixty-four patients with asbestos-related pleural disease, with or without pulmonary disease, were studied. Lung sound recording and analysis was carried out with a computerized lung sound analyser, and HRCT of the chest, as well as forced spirometry and diffusing capacity measurement were performed. The fibrosis score correlated positively with the quartile frequencies of the power spectrum of lung sounds in inspiration (f50) and expiration (f50) and crackle count in inspiration, as well as negatively with diffusing capacity. When the patients with crackling sounds and significant fibrosis were excluded (n=18), emphysema correlated negatively with expiratory quartile frequencies of the power spectrum, with f25 and f50. Furthermore, diffusing capacity correlated with inspiratory f25 and forced expiratory volume in one second with inspiratory f50 when crackles and fibrosis were excluded. Changes in lung sounds were significantly associated with radiologically verified abnormalities and gas transfer of pulmonary tissue. High sound frequencies were associated with fibrotic changes of the lung while low sound frequencies with pulmonary emphysema. Acoustic analysis gives complementary clinical information for evaluation of asbestos-related pulmonary disorders.

Aged↗

PubMed1999

A novel method for monitoring liver ethanol injections: activity tissue distribution in rat liver using digital quantitative autoradiography and CH3(14)CH2OH.

Accurate ethanol microdistribution during percutaneous ethanol injections (PEI) have not previously been reported by in vivo monitoring methods (e.g. by using ultrasound or other flow methods). Any real-time imaging method is insufficient to show the gradual diffusion of ethanol and its ultimate spread. Therefore a novel method to study the microdistribution and radiopharmacokinetics of labeled ethanol in rat liver was developed. Rats were injected with C-14-labeled ethanol into the right liver lobe. Liver slices were investigated at 1, 5, 15, and 30 min using a novel digital quantitative autoradiographic (DQAR) method. Tissue slices at 1 and 5 min demonstrated increased activity of C-14-labeled ethanol around the injection site, resulting in a uniform distribution at 15 min. At 30 min, a weak elimination was observed. Our results indicate that in PEI treatment, toxic effects may be found outside the primary injection site. Our DQAR method shows the dynamic spread of ethanol with great anatomical detail. It may therefore be used in future studies on ethanol kinetics in the liver and tumor tissues to optimize the antitumor effect of PEI while minimizing the potential for adverse spread and complications.

Administration, Cutaneous↗

PubMed1999

High-dose methotrexate in combination with interferons in the treatment of malignant pleural mesothelioma.

Twenty six patients with pleural mesothelioma of UICC stage I-IV excluding M1 disease (46% of whom had stage I disease and 38% stage III disease) were treated intravenously with high dose MTX (3 g) and calcium folinate rescue three times at intervals of 2 weeks and three times at intervals of 3 weeks. Natural interferon (IFN)-alpha (3 MIU days 2-10) and recombinant IFN-gamma1b (50 microg m(-2) on days 2, 6 and 10) were injected subcutaneously after each MTX dose. At the end of MTX treatment the IFNs were continued as maintenance therapy until disease progression. Seven partial responses were observed among 24 patients evaluable for response (response rate 29%, 95% confidence interval 13-51%). Median duration of response was 10 months (range 3-24 months). Median survival was 17 months and 1-year and 2-year survival rates 62% and 31% respectively. The toxicity of the chemo-immunotherapy was acceptable. Treatment was stopped in one patient who developed grade IV neurological toxicity. MTX dose reductions were rare (two patients with grade 1-2 renal toxicity). The combination of high dose MTX and IFN-alpha and IFN-gamma is active against malignant pleural mesothelioma and well-tolerated. The survival rates are encouraging.

Adolescent↗

PubMed1999

Effect of weight loss and regional fat distribution on plasma leptin concentration in obese women.

OBJECTIVES: To investigate how circulating leptin concentrations are related to regional fat distribution and whether moderate weight loss alters these relationships. DESIGN: A 6 month, clinical weight reduction trial with measurements before and after weight loss. SUBJECTS: 38 healthy, obese women (age: 44.3+/-9.9 y, BMI: 34.0+/-4.0 kg/m2). MEASUREMENTS: The following measurements were made. 1. indices of obesity and fat distribution: weight, body mass index (BMI), hip circumference (peripheral fat), waist circumference, total body fat (bioelectrical impedance), abdominal fat distribution: visceral fat and abdominal subcutaneous fat (ultrasonography); and 2. Biochemical measurements: plasma leptin and serum insulin. RESULTS: Baseline plasma leptin concentrations were three-fold higher in obese women than in normal weight controls. After weight loss averaging 8.4 kg (9.0%), plasma leptin decreased by a mean of 22.3% (P < 0.001), corresponding to body fat decrease of 16.6% (P < 0.001), abdominal subcutaneous fat decrease of 17.4% (P < 0.001) and visceral fat decrease of 18.7% (P < 0.001). The total amount of body fat correlated with plasma (serum) leptin before (r = 0.64, P < 0.001) and after (r = 0.75, P < 0.001) weight loss. Plasma leptin concentrations expressed per kg of body fat did not change significantly during weight loss. After controlling for body fat, baseline leptin concentrations were significantly associated with hip circumference (r = 0.57, P < 0.001) but not with any indices of abdominal fat distribution. After weight loss the associations became significant for hip and waist circumference as well as for visceral and abdominal subcutaneous fat. Changes in leptin correlated with changes in all indices of obesity except visceral fat. CONCLUSIONS: Plasma leptin concentrations reflect not only total fat mass but also adipose tissue distribution, especially peripheral fat. Plasma leptin values per kilogram of fat mass do not change significantly with modest weight loss.

Abdomen↗

PubMed1999

MR imaging in suspected acute trauma of wrist bones.

OBJECTIVE: The purpose of this study was to evaluate the findings of MR imaging compared to plain radiography in acute wrist trauma. METHODS: Radiography and MR imaging (obtained at 1.5 T) of 67 patients (38 female, 29 male, aged 15-80 years) were analysed by three senior radiologists in a blinded random fashion. RESULTS: One-third (n= 13) of the 37 fractures observed on MR images were missed on the radiographs. The McNemar test indicated significant differences in diagnoses between radiography and MR. CONCLUSION: We recommend that MR imaging should be considered in the diagnosis of acute wrist trauma when: 1) There is a clear discrepancy between the clinical status and a negative radiography and when splint treatment would increase cost by causing occupational restrictions; and 2) Healing of trauma diagnosed as contusion or distension does not occur within the expected time.

Adolescent↗

PubMed1999

MR imaging in biofix-osteosynthesis.

PURPOSE: Osteosynthesis by means of bioresorbable implants, mostly of self-reinforced poly-L-lactide (SR-PLLA), has been used in humans for about 10 years. The aim of this study was to examine the controversy between histological studies confirming fragmentation of the biomaterial and radiological studies showing no breaking of the material. MATERIAL AND METHODS: Six patients with displaced malleolar fractures operatively treated with biodegradable SR-PLLA screws underwent MR examinations at 1.5 T, immediately postoperatively and after one to two years. RESULTS: The biodegradable osteosynthetic screws were clearly seen on all MR images. Of 12 screws, 6 were broken at the final examination (5 syndesmotic transfixation screws and 1 screw through the growth cartilage). CONCLUSION: The breaking of a biodegradable osteosynthesis is possible to document on MR images.

Absorbable Implants↗

PubMed1998

Spin lock and magnetization transfer MR imaging of local liver lesions.

The present study was designed to evaluate tissue contrast characteristics obtained with the spin-lock (SL) technique by comparing the results with those generated with a magnetization transfer(MT)-weighted gradient echo [GRE, echo-time (TE)=40 ms] sequence. Twenty-eight patients with hepatic hemangiomas (n=14), or metastatic liver lesions (n=14) were imaged at 0.1 T by using identical imaging parameters. Gradient echo, single-slice off-resonance MT, and multiple-slice SL sequences were obtained. SL and MT-effects were measured from the focal liver lesions and from normal liver parenchyma. In addition, tissue contrast values for the liver lesions were determined. Statistically significant difference between the SL-effects of the hemangiomas and metastases, and also between the MT-effects of the lesions was observed (p < 0.02). Tissue contrast values for the lesions proved to be quite similar between the SL and MT techniques. Our results indicate that at 0.1 T multiple-slice SL imaging provides MT based tissue contrast characteristics in tissues rich in protein with good imaging efficiency and wide anatomical coverage, and with reduced motion and susceptibility artifacts.

Adult↗

PubMed1998

Gd-DTPA as an alternative contrast agent in conventional and interventional radiology.

PURPOSE: Patients with contra-indications to iodine-based contrast media present problems in radiological examination. In this study, we evaluated Gd-DTPA as an alternative contrast agent in conventional and interventional radiology. MATERIAL AND METHODS: The undiluted contrast agent Gd-DTPA meglumine (469 mg/ml, Magnevist) was used in 10 examinations in 8 patients. A dosage of 20-45 ml was used in 5 conventional studies: endoscopic retrograde cholangiography, cystography, urethrocystography, and 2 retrograde pyelographies. A dosage of 10-120 ml was used in 5 interventions: 1 percutaneous nephrostomy, and 4 biliary tract drainages. RESULTS: The image quality was adequate in all studies. No adverse pharmacological reactions occurred; however, there was renal extravasation of Gd-DTPA which did cause temporary pain in 1 patient at bilateral retrograde pyelography. CONCLUSION: Gd-DTPA may be used as an alternative contrast medium in selected conventional and interventional roentgenological studies when iodine is contra-indicated.

Adult↗