Effects of iodinated contrast agents in MR imaging.

PURPOSE: To investigate the effects of iodinated contrast agents in MRI. MATERIAL AND METHODS: Twenty patients were examined with MRI immediately, 8 and 24 h after lumbar myelography. Signal intensities and calculated T1- and T2-relaxation times of different iodinated contrast agents, a dilution row of iopamidol, and a mixture of CSF and iotrolan were compared with physiological saline solution using different T1- and T2-weighted sequences. 1H-spectroscopy was performed with several solutions containing iodine or other substances. RESULTS: A fluid-fluid level of the CSF existed in the lumbar dural sac in all patients immediately after lumbar myelography with a non-ionic iodinated contrast agent. Increased signal intensity on T1-weighted and decreased signal intensity on T2-weighted sequences was found for all contrast agents, as well as for the dilution row, compared with physiological saline solution. The structure of the side chains of the contrast agents is responsible for the T1- and T2-shortening effect. CONCLUSION: It is important to be aware of the effect of iodinated contrast agents in MRI. To avoid misinterpretation of atypical findings, MRI of the spine should not be performed earlier than 24 h after myelography.

[Contrast-enhanced subtraction MRT in the spin-echo technic]. / Kontrastverstärkte Subtraktions-MRT in Spin-Echo-Technik.

PURPOSE: The aim of the retrospective study was to determine whether subtraction of spin-echo images is useful for estimating intensity and extension of contrast enhancement when practised in daily routine diagnostic work. METHODS: 348 patients with different diseases of the musculoskeletal and neuro system were examined with MRI using a T1-weighted spin-echo sequence before and after application of 0.1 mmol/kg Gd-DTPA with subsequent subtraction of both measurements. Usefulness of the source images, pictorial quality of subtracted images and intensity of contrast enhancement were assessed subjectively. RESULTS: Subtracted images were of sufficient quality in 85% of the cases, whereas source images were always usable except in 9 patients. It was easier to visualise the extent of contrast enhancement in subtracted than in non-subtracted images in examinations of the musculoskeletal system, whereas there was no difference in the neuro system. Contrast enhancement could definitely be excluded in 15% of the patients and was stated to be of low, medium and high intensity in 21%, 45% and 19%, respectively. In comparison with subtracted images lesions were stated to appear larger in 62% and 87%, smaller in 25% and 13%, and of the same size in 13% and 0% for T2-weighted and fat-suppressed images, respectively. CONCLUSION: Subtraction of spin-echo images before and after application of contrast media is useful for estimating intensity and extension of contrast enhancement without essentially increasing time and costs of the examination. Extension of contrast enhancement in musculoskeletal lesions rarely correlates with the extension of signal changes in T2-weighted and fat-suppressed images.

[Experiences with a new breast localization needle]. / Erfahrungen mit einer neuen Mammalokalisationsnadel.

In view of the increasing number of biopsies of non-palpable lesions of the female breast we found an ideal localisation system in the Hawkins breast localisation needle. Localisation was successful without technical problems in 31 out of 34 patients. The special advantages of the needle are its stability in position and excellent maneuverability due to the construction of the needle. The very simple handling of the needle is an advantage not only for the radiologist but also for the surgeon.

[Hypertension as risk factor for increased rate of side effects in the framework of breast carcinoma irradiation]. / Hypertonie als Risikofaktor für erhöhte Nebenwirkungsraten im Rahmen der Mammakarzinombestrahlung.

The rate of radiation-induced side-effects is dependent from exogenous technical and endogenous factors. Widespread endogenous factors are arterial hypertension and other cardiovascular diseases. 130 breast cancer patients were retrospectively evaluated for side-effects to estimate the influence of arterial hypertension. All were treated with mastectomy and irradiation (telecobalt) and consecutively followed. 79 patients had normal blood pressure, 51 showed arterial hypertension. Hypertension proved to be the strongest endogenous factor for the development of side-effects. In contrast to the patients with normal blood pressure those with hypertension showed significant more arm lymphedema (p less than 0.005) and telangiectasia (p less than 0.0001). Other endogenous factors, like cardiovascular diseases or obesity, taken together led only to a higher rate of subcutaneous fibrosis (p less than 0.002). Patients with arterial hypertension should receive axillary radiation only for strict indications and perhaps with a reduced dosage.

MR imaging in graft-dependent recurrent hyperparathyroidism after parathyroidectomy and autotransplantation.

The purpose of this study was to compare the value of MR imaging versus sonography in the detection of hyperfunctioning transplanted parathyroid tissue. After parathyroidectomy and autotransplantation of parathyroid tissue to the forearm, 14 patients were examined with sonography and MR imaging. Five of these patients had recurrent hyperparathyroidism. In three of these five, sonography found one echolucent nodule. MR imaging in all three patients detected, in addition to this nodule, other small nodules of hyperplastic parathyroid tissue, which were confirmed intraoperatively. In the other two patients, sonographic and MR imaging findings were negative. Further investigations showed that both patients had a fifth parathyroid gland. In the patients without recurrent hyperparathyroidism, sonography showed scar tissue only, whereas MR imaging found some tiny, contrast-enhancing structures in two patients, probably autograft material. MR imaging seems to be more sensitive than sonography in detecting hyperfunctioning autotransplanted parathyroid tissue.

Chest ultrasound in diagnosis of pulmonary embolism in comparison to helical CT.

UNLABELLED: To many people die because of undiagnosed pulmonary embolism. Common pulmonary embolism is the most unexpected mortal event in necropsy, antemortem correctly diagnosed in 18-39%. The diagnostic value of chest ultrasound (CUS) has been investigated. METHODS: 117 (68 women, 49 men) patients with clinical suspicion of pulmonary embolism underwent chest sonography and spiral computed tomography (CT). Final diagnosis has been made by CT respective with echo-cardiography, venous duplex sonography and fibrin dimer tests. RESULTS: Finally, 70 patients suffered from pulmonary embolism. The chest sonograms showed averaged 1.5 x 2.8 cm (0.5-8.5) large triangular or rounded hypoechoic lesions, mean 2.6 pro patient, similar in form and size as in CT. Fresh reperfusionable infarcts were homogenous and hypoechoic. Older infarcts were well demarcated, mainly wedge shaped. A hyperechoic reflex in the center corresponds to the bronchiole: a sign of segmental involvement. The sensitivity of chest ultrasound was 94%, the specificity 87%, positive predictive value 92%, negative predictive value 91%, accuracy 91%. Overall 61 patients had PE in CT, in 47 (67%) cases a direct emboli detection was possible. 14 patients had peripheral lung consolidations without detectable emboli, but fibrin-dimer tests were positive in all cases, there was deep vein thrombosis diagnosed and they showed signs of PE in echocardiography. Spiral CT showed a sensitivity of 85%, a specificity and a positive predictive value of 100%, a negative predictive value of 83% and an accuracy of 92%. CONCLUSION: CUS can improve diagnosis of pulmonary embolism. Sonography also reveals small infarcts which remain undetected with other imaging procedure such as helical CT.

The value of intraoperative angiography in surgery of intracranial aneurysms: a prospective study in 126 patients.

The value of intraoperative digital subtraction angiography in surgery for intracranial aneurysms, the benefits and cost-effectiveness are a matter of discussion. We prospectively studied 126 patients with 144 aneurysms, most on the anterior intracranial circulation, who underwent clipping and intraoperative angiography. Follow-up was 28.4 +/- 13.1 months. We tried to work out the indications for intraoperative angiography of the anterior circulation and its cost-effectiveness. In 10.3 % of patients (9 % per aneurysm) unexpected findings were shown by intraoperative angiography: inadequately clipped aneurysms in 10 (7.9 %), a completely unclipped aneurysm in one (0.8 %) and occluded major arteries in two (1.6 %). A broad neck was a variable of statistical significance for inadequate clipping or stenosis or occlusion of an adjacent vessel. There was a strong trend for aneurysms more than 15 mm in diameter to be "risky". Their site was not a predictive factor. We believe that intraoperative angiography is indicated in surgery not only on large and giant aneurysms, but also broad-based aneurysms of the anterior cerebral circulation regardless of their size. It is cost-effective compared to postoperative angiography. The rate of stroke in our hands was 0.8%.