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T Vehmas

Publications and source records attributed to T Vehmas.

At least 55 records · Page 3Linked to original sources
PubMed1998

Magnetic resonance imaging of clinically localized prostatic cancer.

PURPOSE: We assess the accuracy of endorectal coil magnetic resonance imaging (MRI) for detecting tumor localization, capsular penetration and seminal vesicle invasion in clinically organ confined prostate cancer. We also evaluate intra-observer and interobserver agreement in interpreting MRI studies. MATERIALS AND METHODS: MRI studies of 51 consecutive patients a mean of 61 years old with biopsy proved prostate cancer were retrospectively read twice by 2 radiologists in random order. Both radiologists marked tumor localization, capsular penetration and seminal vesicle invasion on standard tumor maps. These findings were compared with the histopathological results of radical prostatectomy specimens. RESULTS: The overall accuracy of detecting cancer localization was 61%. The detection rate for cancer foci less than 5 mm. was only 5% but for lesions greater than 10 mm. it was 89%. There was 91 and 80% accuracy for detecting capsular penetration and seminal vesicle invasion, respectively. Sensitivity and specificity were 60 and 63, 13 and 97, and 59 and 84% for localization, capsular penetration and seminal vesicle invasion, respectively. Intra-observer and interobserver agreement ranged from fair to good (kappa coefficient 0.240 to 0.647). CONCLUSIONS: Endorectal MRI seems to be better than previously reported for detecting seminal vesicle invasion and tumor foci in the anterior half of the prostate. Sensitivity in detecting minor capsular penetration of the tumor was low, which can probably be improved by methodological development. MRI may be useful for locating cancer foci in patients with high prostate specific antigen values but repeatedly negative biopsy findings.

Aged↗
PubMed1997

Optimising imaging parameters in experimental spiral CT.

PURPOSE: This in vitro study was conducted to analyse lesion detection and relative radiation exposure in different CT techniques. MATERIAL AND METHODS: We used a plastic phantom (12 x 8 x 2 cm) containing holes filled with air or fluid of varying densities to simulate lesions. This was imaged with Siemens Somatom Plus S and GE High Speed Advantage units. We varied table feeds (3 and 6 mm/s in Siemens and 3 and 4.5 mm/s in GE) and increments (2 mm and 4 mm) while keeping collimation at 3 mm. The SmartScan program of GE and the reformatting algorithm of Siemens were also analysed. To evaluate the different methods, the phantom lesions were counted by 3 observers. Radiation exposures associated with each technique were also measured. RESULTS: The images reformatted to a coronal direction were significantly inferior (p < 0.01) to those in other techniques. The use of SmartScan did not influence lesion detection, nor did changes in pitch or increment. Spiral and non-spiral techniques proved to be equal. Radiation exposure was lowest when a greater pitch or the SmartScan program was used. CONCLUSION: Radiation exposure in CT can be limited without significantly impairing the image quality by using low-dose techniques. Reformatting to a coronal direction should be used with care as it debases the image quality.

Humans↗
PubMed1997

Structural changes in the renal proximal tubular cells induced by iodinated contrast media.

The renal morphologic changes induced by intravenously injected contrast media (CMs) were studied in 40 Wistar rats which had been deprived of water 24 h before the CM injection. In the first part of the investigation, the kidneys were fixed by perfusion for light and electron microscopy 2 h after injection of 3 g iodine/kg of iopamidol, iobitridol or iohexol. Control animals received physiologic saline. In the second part of the study, the fixation was performed 48 h after the injection of the corresponding dose of iobitridol or iohexol. The structural changes were semiquantitatively evaluated by two independent observers unaware of the agent injected. The lysosomes of the proximal convoluted tubular cells showed moderate changes 2 h after the iopamidol injection. Iobitridol and iohexol induced prominent lysosomal alterations with signs of cytoplasmic injury. After 48 h, the changes induced by iobitridol had almost disappeared, whereas the iohexol group still showed a statistically significant vacuolization. Although the general physicochemical properties of iobitridol and iohexol appear similar in vitro, the different lysosomal alteration might reflect differences in their characteristics in vivo.

Animals↗
PubMed1997

Radiation exposure during standard and complex interventional procedures.

Radiation doses given during standard and complex interventional procedures were compared. Screening times, dose-area products, and radiologists' forehead and finger doses were recorded during 28 standard percutaneous drainages and 10 complex drainages (eight combined procedures and two failed procedures). The median screening times (8.75 min) and finger doses (84 microGy) during standard drainages were less than those during complex drainages (20.5 min, p = 0.0005 and 163 microGy, p = 0.0003). Dose-area products and forehead doses were also lower, but not significantly. Previously published series on radiation measurements lack data on complex procedures. This may bias the results, since combined and failed interventions, which are common, are associated with higher radiation exposure than are standard procedures.

Humans↗
PubMed1997

Hawthorne effect: shortening of fluoroscopy times during radiation measurement studies.

Screening times were recorded before (n = 92, 13 radiologists) and after (n = 75, 6 radiologists) commencing a protocol with dose-area product (DAP) measurements and filling of structured questionnaires. Fluoroscopy times were significantly (p = 0.0001) longer before starting these measurements (median 4.3, mean 5.2 min) than during them (median 3.2, mean 3.6 min), which indicates a Hawthorne effect. Fluoroscopy times did not increase during the DAP measurement period up to 21 barium enemas and a study period of up to 45 days per radiologist. Previous fluoroscopic radiation measurements based on action during an analysis period may be biased towards too short fluoroscopy times and too low doses. Radiation measurement, even if not scientifically indicated, seems a practical way of reducing doses.

Barium Sulfate↗
PubMed1996

Effect of injection speed on the spread of ethanol during experimental liver ethanol injections.

RATIONALE AND OBJECTIVES: Percutaneous ethanol injection therapy may cause serious complications, most likely due to the uncontrolled spread of ethanol. The authors changed the speed of the injection into postmortem pig livers and examined the adverse spread of ethanol from the injection site and the shape and size of the resulting lesion. METHODS: One milliliter of 96% ethanol was injected into pig livers under sonographic guidance at different speeds (0.075-0.91 mL/s). The spread (graded from I to III) and the volumes and shapes of the resulting lesions seen after dissection were recorded and correlated with the injection speed. RESULTS: When increasing the speed of the injections the large, grade III spread increased significantly (P < .01). The lesions created by more rapid injection were less spherical than were those created by slower injections (P = .08). The volumes of the lesions were not affected by the injection speed. CONCLUSION: This experimental model suggests that in percutaneous ethanol injection therapy, rapid injection (> 0.3-0.4 mL/s) should be avoided to reduce the uncontrolled spread of ethanol. Spherical spreading of ethanol around the needle tip is best achieved with slow injection.

Animals↗
PubMed1996

Complications following high-dose percutaneous ethanol injection into hepatic tumors.

PURPOSE: Percutaneous ethanol injection therapy (PEIT) with a 2-10 ml ethanol dose per session is widely used in the treatment of small hepatocellular carcinoma. Larger doses have been restricted for fear of complications. The aim of the present study was to make a retrospective evaluation of the complications following treatment of hepatic tumors with high doses of ethanol (up to 200 ml). MATERIAL AND METHODS: The medical records of 15 patients treated repeatedly with PEIT were reviewed retrospectively to detect side effects or complications. Eleven of these patients had undergone transarterial chemoembolization (TAE) prior to PEIT. Of 173 ethanol injections in doses of 2-200 ml (mean 49 ml), more than 10 ml had been injected on 138 occasions. The chi-square test was used to evaluate the differences in pain frequency among the various dosage groups. RESULTS: Serious complications did not occur. Pain was a common side effect, occurring in 48% of the procedures. Immediate pain during the treatment was related to the ethanol dose and increased significantly with increasing doses (p < 0.01). Other side effects were rare. CONCLUSION: PEIT with doses higher than previously reported seems to be safe. This should encourage further clinical studies that aim at fully working out the clinical value of such treatment.

Chemoembolization, Therapeutic↗
PubMed1996

Gd-DTPA in male urethrography. A case report.

Patients with a case history of severe side-effects from iodine-containing contrast media present problems in later radiological examination. We report here on an alternative, the first extravascular use of Gd-DTPA in an X-ray urethrography. By using the standard processing algorithm of our digital radiographic equipment and 60 ml undiluted Gd-DTPA meglumine (469 mg/ml) we achieved good contrast and could exclude the suspected urethral diverticulum in a 26-year-old man. No adverse reactions occurred. Gd-DTPA seems to offer a reasonable contrast and may be used as an alternative extravascular contrast medium in selected conventional radiographic studies.

Adult↗
PubMed1996

Toxicity of ethanol in low concentrations. Experimental evaluation in cell culture.

PURPOSE: To define the threshold ethanol concentration that is toxic to cultured cells. METHODS: Three malignant cell lines and freshly isolated normal rat hepatocytes were exposed to 0-50% (vol.) ethanol (concentrations used were 0, 5, 10, 15, 20, 25, 30, 40 and 50%) on tissue culture plates for 0.25-60 min (exposure times used were 0.25, 5, 10, 20, 30, 40 50 and 60 min). Cytotoxicity was estimated by trypan blue exclusion test and from 3H-thymidine incorporation. RESULTS: All cells were killed by a 15-s exposure to 30-40% ethanol while a concentration as low as 15-20% gave a total response after 5-10-min exposures. After a one-hour exposure of F9 carcinoma cells and hepatocytes, a total or nearly total response was achieved with 10% ethanol. The cytotoxic effect was thus dependent both on the exposure time and on the concentration of ethanol. There were no significant differences in ethanol tolerance among the cell types. CONCLUSION: Ethanol seemed to kill cells in the cell culture effectively in much lower concentrations than those currently used in tumour ablation.

Animals↗
PubMed1996

Measuring visceral adipose tissue content from contrast enhanced computed tomography.

OBJECTIVE: To study whether visceral adipose tissue (VAT) content can be measured retrospectively from routine contrast enhanced computed tomographic (CT) studies in order to avoid extra radiation exposure and to enable epidemiological quantifications of VAT in various diseases. SUBJECTS AND METHODS: Seven patients were examined by CT and the VAT contents (from -150 HU to -50 HU) were quantified both from their corresponding unenhanced and enhanced images (n = 8-18 per patient). RESULTS: The measured VAT volume in enhanced images was smaller (p = 0.016) than in the corresponding unenhanced images, which is most likely due to the adverse accentuation of partial volume effects. By using our bolus technique, VAT (cm2) in an unenhanced image = 1.11 x VAT in an enhanced image + 2.95, p = 0.0001. Alternatively, rising properly the upper limit for VAT density in an enhanced image compensates the use of i.v. contrast media. CONCLUSION: VAT content may be retrospectively quantified from routine abdominal CT images, but the unfavorable effects of i.v. contrast administration on measurements must be taken into account.

Abdomen↗
PubMed1995

Echogenicity of experimental liver ethanol injections.

Percutaneous ethanol injection therapy under sonographic guidance suffers from the occasional adverse spread of ethanol. We tried to optimize the technique to obtain the maximal echogenicity of injections. Eight dead pig livers were injected with ethanol and the consequent echogenicity was correlated with the time lapse after the injection, the speed of injection, the injected dose and the concentration of ethanol. For the sake of comparison, ethanol was also injected into processed sour milk. The injected lesions became smaller (P < 0.001), less sharply demarcated and less echogenic (P < 0.001) with time. Speeding up the injection (P < 0.05) and concentrating the ethanol (P < 0.05) increased echogenicity, whereas enlarging the dosage did not. Injections of ethanol into processed sour milk induced hyperechoic zones similar to the liver injections. It is concluded that quick injections of concentrated ethanol would be best detected. Injections should be monitored while they are still taking place, because the echogenicity will soon decrease. This immediate echogenicity seems to be caused by flow and the inherent properties of ethanol.

Animals↗
PubMed1994

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.

Adult↗
PubMed1994

Ultrasound monitoring of experimental ethanol injection into pig liver.

RATIONALE AND OBJECTIVES: In percutaneous ethanol injection therapy, uncontrolled spread of ethanol sometimes causes complications. This study tested the accuracy of ultrasonography in showing the spread of ethanol during injection in normal postmortem pig livers. METHODS: Methylene blue-stained 96% (vol) ethanol (0.5-2 ml) was injected into pig livers under sonographic control. The volumes of the sonographically determined areas infiltrated by the injections and the corresponding pale lesions seen after dissecting the livers were measured and compared. The locations of the stained areas were determined. RESULTS: Uncontrolled spread of ethanol was often seen sonographically as hyperechoic lines spreading centrifugally from the injection site. After dissection, nearly all vessels and ducts were stained blue, indicating a major escape of ethanol from the injection sites. The volumes of the sonographically determined injection areas were significantly larger (P < 0.001) than the lesions found after dissection. CONCLUSIONS: Ultrasonography may overestimate the spread of ethanol, making the survival of peripheral tumor cells possible.

Administration, Cutaneous↗
PubMed1993

Fatal liver necrosis following percutaneous ethanol injection for hepatocellular carcinoma.

A 76-year-old man underwent an injection of 5 ml of ethanol for the treatment of a hepatocellular carcinoma 3 cm in diameter. Shortly after the procedure, he had an attack of abdominal pain. His condition soon deteriorated and he died 5 days later. Massive hepatic necroses distant from the injection site and a myocardial infarction were found at autopsy. To our knowledge, this is the first fatality associated with percutaneous ethanol injection therapy.

Aged↗
PubMed1993

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).

Adult↗
PubMed1993

What factors influence radiologists' finger doses during percutaneous drainages under fluoroscopic guidance?

Radiation exposure of radiologists' left and right hands during 44 percutaneous drainages involving fluoroscopy was measured with thermoluminescent dosimeters. Finger doses of 3.4-1,300 microGy (mean 180, median 110) were recorded. Finger exposure seemed to show a significant, positive correlation with the screening time, but not with the patients' body mass indexes or ages. The mean personal doses of the radiologists were different and, in one case, the difference between the individual radiologists' doses was statistically significant. The personal working technique may therefore partly explain the amount of radiation exposure to the fingers.

Adult↗