Adsorption of mycotoxins.

In vitro binding studies with different mycotoxins are often made to test various adsorbents for their ability to detoxify these toxins in animal feed. In this study different clays were investigated for their ability to bind aflatoxin B1, zearalenone, ochratoxin A and deoxynivalenol in two different buffer systems (pH 3 and pH 6.5). In addition chemical/physical properties like cation exchange capacity and the concentration of exchangeable Ca(2+), Na(+), Mg(2+) and K(+) ions in the adsorbents were determined to establish if there is a connection between these parameters and the capacity to bind mycotoxins. Most of the tested clays showed high adsorption rates for aflatoxin B1 in both buffer systems. Adsorption rates for ochratoxin A and zearalenone of the tested clays were in the range of 0-100%. None of the tested adsorbents had the ability to bind deoxynivalenol. In this study no correlation between the cation exchange capacity of the clays or the concentration of exchangeable Ca(2+), Na(+), Mg(2+) and K(+) ions and the ability to adsorb mycotoxins could be investigated.

Efficacy of thrombolytic therapy in pulmonary embolism determined by MION-enhanced MRA: an experimental study in rabbits.

RATIONALE AND OBJECTIVES: This study determined whether contrast-enhanced magnetic resonance angiography could be used as a noninvasive imaging technique to determine the therapeutic effect and endpoint in thrombolysis of acute pulmonary embolism in an animal model. METHODS: New Zealand white rabbits (n = 18) were anesthetized and mechanically ventilated. Single (n = 12 emboli) or dual (n = 12 emboli in 6 animals) pulmonary emboli were created by injecting autologous thrombi through a right internal jugular venous approach. Three-dimensional time of flight (TOF) magnetic resonance angiograms were obtained after intravenous administration of 2 mg Fe of a long circulating monocrystalline iron oxide. Animals then received 5000 IU heparin and 1.3 mg recombinant tissue plasminogen activator/kg intravenously, and magnetic resonance angiography was repeated 30 minutes and 60 minutes after initiation of thrombolytic therapy. RESULTS: MION-enhanced magnetic resonance angiography accurately detected pulmonary emboli in all rabbits. Thrombolysis during the observation period was successful in 8 of the 18 animals. In animals with a single embolus, the revascularization rate was 50% (6 of 12 emboli). The rate was 33% (4 of 12 emboli) in animals with multiple emboli. Magnetic resonance angiography allowed determination of thrombus resolution or thrombus persistence. CONCLUSIONS: It was feasible to diagnose pulmonary embolism accurately in this experimental study and to monitor thrombolysis of pulmonary emboli by MION-enhanced magnetic resonance angiography.

[Magnetic resonance tomography (MRT) of the breast in problem patients]. / Magnetresonanztomographie (MRT) der Mamma bei Problempatientinnen.

Over the past few years MRI has become important in the evaluation of inconclusive mammograms. These studies were performed on high-field strength machines, which have the disadvantage of limited accessibility. We evaluated 185 investigations on 169 patients on a 0.5 Tesla MR machine using a dynamic sequence and gadolinium (Gd) DTPA. The results in 107 patients were correlated with the histological findings and MRI assessment proved correct in 44 of 47 benign lesions (93.6%) and 57 of 60 malignant lesions (95%). The 3 false positive results occurred in patients with mastitis, fibroadenoma and an ectatic vessel, respectively. Of the 3 false negative results 2 occurred in patients with microcarcinomas and were due to partial-volume artefacts, whilst the third was due to a technical error. These results compare with those reported in the literature using mainly high-field strength machines. Furthermore, unsuspected second tumours were diagnosed in the ipsilateral breast of 6 women and infiltration of the adjacent thoracic wall in 4 women, findings which had not been evident on mammography. Hence, our results indicate that a mild-field strength MR machine is a valuable tool not only for the non-invasive differentiation between benign and malignant lesions of the breast, but also for planning therapeutic strategy.

[Acute renal vein thrombosis in children. Early detection with duplex and color-coded Doppler ultrasound]. / Akute Nierenvenenthrombose bei Kindern. Früher Nachweis mit Duplex- und farbkodierter Dopplersonographie.

Two children with clinically suspected renal vein thrombosis were evaluated by duplex Doppler sonography and colour flow imaging. Both cases presented unspecific findings with an enlarged kidney and loss of cortico-medullary delineation on gray-scale ultrasound, but an unusual flow pattern with retrograde plateau-like frequency shifts during diastole. No venous signal could be obtained. By colour flow imaging only the main renal artery and its proximal branches could be visualised with a reverberating oscillation of blood flow. In addition, partial thrombosis of inferior vena cava in one patient and iliac vein thrombosis in the other could be demonstrated. Clinical improvement during fibrinolytic therapy in one case and nephrectomy in the other case confirmed the diagnosis.

Difficulties in examination of the origin of the vertebral artery by duplex and colour-coded Doppler sonography: anatomical considerations.

Despite progress in ultrasonographic techniques visualisation of the origin of the vertebral arteries, particularly the left, by duplex and colour Doppler imaging, still poses a problem in a significant number of patients. In anatomical and radiological studies we demonstrated an anomalous origin in 6%, the left vertebral artery originating directly from the aorta in most cases. The origin from the subclavian artery was found to be posterior in 44% and inferior in 6%. The V1 segment of the vertebral artery (from its origin to the entry into the foramen transversarium) was tortuous in 47% of cases. These anatomical variants and variations in the course of the vessel contribute to the nonvisualisation of the origin of the vertebral artery by duplex and colour Doppler imaging. With respect to tortuosities technical modifications for better visualisation are suggested and possible implications for surgery are discussed.

Degenerative Achilles tendon disease: assessment by magnetic resonance and ultrasonography.

As Magnetic Resonance (MR) imaging and Ultrasound (US) allow the evaluation of soft-tissue structures not previously possible with other imaging techniques, a clinical study has been undertaken to determine the value of these two modalities in the detection of lesions in the Achilles tendon (AT), other than acute total rupture. Seven healthy subjects and 28 symptomatic patients with Achillodynia and/or signs of thickening of the AT were investigated with MR and US; all results were compared with the clinical features. Surgical findings were available in 14 patients. The patients were divided into three groups; those with tendon thickening, incomplete and complete chronic ruptures. Thickening of the AT was easily detected with both methods. MR was superior in the detection of incomplete tendon rupture and in the evaluation of various stages of chronic degenerative changes. We conclude that only if US remains unclear, an additional MR study should be performed and together with the clinical diagnosis indication for surgery can be made more efficient.

[Saphenous vein bypass stenoses, early diagnosis with color coded Doppler sonography]. / Vena-saphena-Bypass-Stenosen, Frühdiagnose mittels farbkodierter Dopplersonographie.

In a prospective study 54 patients with 62 saphenous vein arterial bypass grafts were examined by colour-coded Doppler sonography and angiography. Five cases of graft occlusion were diagnosed by colour-coded Doppler sonography and confirmed by angiography. In comparison with angiography, colour-coded Doppler sonography showed a sensitivity of 92% and a specificity of 100% in the detection of focal graft stenosis. Only two stenoses in the region of the distal anastomosis could not be detected by colour-coded Doppler sonography. In 28 cases a marked dilatation of the proximal anastomosis was found corresponding to the surgically used patch angioplasty. Within this dilated bypass segment, turbulence and flow reversal zones were demonstrated, which might be predisposing factors for graft stenosis. Colour-coded Doppler sonography can accurately detect saphenous vein arterial bypass graft stenoses and should be routinely used in postoperative screening.

Quantitation of structural distortion of the cervical neural foramina in gradient-echo MR imaging.

Quantitative errors (due to magnetic susceptibility artifacts) in the measurement of the cervical spinal neural foramina with fast gradient-echo (GRE) magnetic resonance imaging were assessed. Cylindric phantoms of different materials were used to demonstrate the nature of magnetic susceptibility artifacts, emphasizing the dependence of the artifact on tissue geometry. Neural foramina diameters measured on thin, sagittal GRE and spin-echo (SE) images through the neural foramina of a fresh human cervical spine specimen were then compared with direct measurements with calipers. The GRE images showed more apparent narrowing than did the SE images. The absolute distortion of seven neural foramina was rather constant (less than two pixels) on the GRE images; therefore, the relative distortion was inversely proportional to the size of the neural foramen, ranging up to 10% in the upper cervical region at a short TE. The absolute and relative distortion increased as TE increased. At a constant TE, the structural distortion did not change with different TRs or flip angles. The shortest possible TE is recommended in evaluation of the cervical spine.

[Varicosis orbitalis. Its demonstration by color-coded Doppler sonography and computed tomography]. / Varicosis orbitalis. Nachweis mittels farbkodierter Doppler-Sonographie und Computertomographie.

Three patients with intermittent exophthalmos were studied by computed tomography (CT) and colour-coded Doppler sonography (CCDS). By CT the possible diagnosis of an orbital varix was established. CCDS, however, with the dynamic evaluation and realtime direct imaging of flow and the possibility of examination in different positions facilitated the diagnosis of this orbital vascular disorder without the need for any contrast material. This technique may prove to be a useful adjunct to computed tomography for the evaluation of suspected vascular lesions of the orbit. Surgery confirmed the diagnosis in all patients.

[Vascular space-occupying lesions of the carotid artery--detection with color-coded Doppler sonography. Comparison with duplex sonography and angiography]. / Vaskuläre Raumforderungen der Arteria carotis--Nachweis mit der farbkodierten Dopplersonographie. Vergleich mit Duplexsonographie und Angiographie.

Nine patients with a cervical tumour, diagnosed by duplex Doppler sonography were additionally evaluated by colour-coded Doppler sonography (CCDS). The duplex Doppler diagnosis of three internal carotid artery aneurysm was confirmed by CCDS in only one patient. In the remaining two cases CCDS identified a marked coiling of the internal carotid artery. Three low echogenic lesions, interpreted as cervical lymphomas by conventional Doppler sonography were identified as two internal carotid aneurysm with partial thrombosis and a carotid body tumour in the third patient by CCDS. Duplex-Doppler sonography and CCDS agreed in the diagnosis of two AV-malformations and one carotid body tumour. Angiography confirmed the CCDS-diagnosis in 7 patients. In the two patients with coiling of the ICA angiographic evaluation was not performed. Thus, CCDS was superior to duplex Doppler sonography in the evaluation of vascular lesions of the extracranial section of the carotid artery and provided additional diagnostic information.

Color-coded Doppler sonography of vertebral arteries.

Color-coded Doppler sonography of the vertebral arteries was performed in 86 patients who had a history of vertebrobasilar disease. The origin of the artery was visualized in 87.2% on the right and 70.9% on the left side. The inter-transverse portion of the vertebral artery was visualized in 95% on the right and 97% on the left side. The atlas loop could be visualized in 88.4% on the right and 84.9% on the left side. Pathologic findings were hypoplasia (n = 4), stenosis (n = 19), dissection (n = 2), occlusion (n = 7), kinking (n = 12), cervical tumors (n = 3), and subclavian steal syndrome (n = 3). Nine postoperative patients had subclavian and vertebral artery reimplantation to the common carotid artery. The characteristic color-coded Doppler sonographic features of these findings are presented and discussed.

[The patency of the external and internal carotid arteries in patients with occlusion of the common carotid: detection using color-coded Doppler sonography]. / Durchgängigkeit der Carotis externa und interna bei Patienten mit Carotis-communis-Okklusion: Nachweis in der farbkodierten Doppler-Sonographie.

Common carotid artery occlusion is not necessarily associated with thrombosis of the ipsilateral internal carotid artery. Noninvasive imaging of the carotid bifurcation with colour-coded Doppler sonography demonstrated patency of the external and internal carotid arteries distal to a common carotid occlusion in 4 patients which could be proven surgically. Identification of internal carotid artery patency could be demonstrated by angiography in two of the patients while in the other two cases angiography was inconclusive. Thus, CCDS provided a correct diagnosis of the internal carotid patency in these patients with common carotid occlusion.

[Velocity variance function: additional information in color-coded Doppler sonography of the carotids]. / Velocity-Variance-Funktion: Zusatzinformation in der farbkodierten Doppler-Sonographie der Karotiden.

A new software, called the velocity variance programme, by which flow disturbances are additionally colour-coded, was systematically applied with colour Doppler sonography in 59 patients with stenotic atheromatous lesions of different grades in the carotid bifurcation. A direct comparison with and without using this programme was made. In group 1 (n = 23) with stenosis of the internal carotid artery of more than 50% it could be demonstrated that flow disturbances were maximally in the region immediately downstream of the stenosis and complete dissipation of these effects occurred within 8-10 vessel diameters downstream. Moreover, a direct correlation between the size of the region of disturbed flow and the irregularity of the stenotic plaque surface within the stenosis could be demonstrated. Distal to the stenosis there was an inverse relationship between the extension of disturbed flow and the length of the stenosis and a direct relationship to the grade of the stenosis and the irregularity of the plaque surface. In patient group 2 (n = 36) with less than 50% diameter reduction, a local flow disturbance near the atheromatous plaque was shown in 27 patients. In eighteen of these patients the region of disturbed flow could be revealed only by using the velocity variance programme. The importance of this non-invasive in-vivo visualisation of flow disturbances in the carotid bifurcation is discussed.

MR imaging of vertebrobasilar vascular disease.

Sixteen patients with vascular lesions of the vertebral and basilar arteries were studied with magnetic resonance imaging. The vascular abnormalities included seven cases of atherosclerotic disease with partial or complete thrombosis, six aneurysms, two cases of vertebrobasilar dolichoectasia, and one basilar artery dissection. Magnetic resonance effectively demonstrated vascular thrombosis with occlusion as high signal intensity on spin echo (SE) sequences with absence of flow void and no flow enhancement on gradient echo (GRE) images. Nonthrombosed aneurysms exhibited mixed signal intensity on SE images and hyperintensity on GRE images. Intraluminal thrombus also appeared heterogeneous, with variable signal intensity depending on the specific components of hemorrhage present. Correlation of the SE and GRE scans was helpful for distinguishing stasis and turbulent flow from thrombus. Compression of cranial nerves by vascular structures was clearly depicted in both cases of dolichoectasia. Basilar artery dissection was displayed as a focal area of flow void surrounded by a thrombosed false lumen. Magnetic resonance is an effective noninvasive method for evaluating vascular pathology of the vertebrobasilar system.

[Color-coded Doppler sonography of the carotid artery]. / Farbkodierte Doppler-Sonographie der Arteria carotis.

A total of 844 patients were evaluated to compare the value of ultrasonography and color-flow Doppler and to demonstrate the advantage presented by the latter method. In 89%, color-flow assessment was in complete agreement with the duplex assessment. In the remaining 11%, important additional results were discovered in the color-flow examination. Non-stenotic plaques were seen more often (43%) in the wide carotid bulb; stenotic plaques and occlusion were found more often (66% and 82%) in the internal carotid artery. Color-flow Doppler allows the sonomorphological (plaques, stenoses, occlusion) and functional parameters (turbulences, flow enhancement) to be studied at the same time.

[Flow reversal in the carotid bifurcation. Detection using color-coded Doppler sonography]. / Flussumkehr in der Karotisbifurkation. Nachweis in der farbkodierten Doppler-Sonographie.

Pulsatile blood flow within the normal carotid sinus involves at least two distinct components. Beside the laminar antegrade flow, there is a boundary layer separation zone in the posterolateral aspect with transient flow reversal. This flow reversal is well known from in vitro studies. It is now possible to document these flow velocity components using color-coded Doppler sonography. It is hypothesized that if flow separation is detected, this is indicative of a normal condition of the carotid bifurcation. When atherosclerosis develops, it involves preferentially the posterolateral bulb region, obliterating the normal configuration of the sinus with consequent loss of the flow separation. Therefore, loss of flow reversal should be indicative of atherosclerosis. We have studied this flow pattern retrospectively in 156 patients (312 arteries). In 4 patients no flow reversal could be detected although no atheromatous lesions could be found at the bifurcation, but in these cases there was no bulb formation in the common carotid artery or in the internal carotid artery. On the other hand, flow reversal was demonstrable in several pathological conditions within the carotid bifurcation. These included plaque formation after the bifurcation in 7 patients, internal carotid artery occlusion at the origin in 12, common carotid artery occlusion despite a patent bifurcation in 4, and marked dilatation of the lumen forming a pseudobulb following disocclusion of the carotid artery in 11 patients.

[Color-coded Doppler sonography of the vertebral arteries]. / Farbkodierte Doppler-Sonographie der Vertebralarterien.

Color-coded Doppler sonography of the vertebral arteries was performed in 86 patients with a history of vertebrobasilar disease. The origin of the artery was visualized in 87.2% on the right and 70.9% on the left side. The interforamen portion of the vertebral artery was visualized in 95% on the right and 97% on the left side. The atlas loop could be visualized in 88.4% on the right and 84.9% on the left side. Pathologic findings were hypoplasia (n = 4), stenosis (n = 19), dissection (n = 2), occlusion (n = 7), kinking (n = 12), and subclavian steal syndrome (n = 3). Nine postoperative patients had subclavian and vertebral artery reimplantation into the common carotid artery. The characteristic color-coded Doppler sonographic features of these findings are presented and discussed.

Renal osteodystrophy. Radiological diagnosis compared with a new radioimmunoassay method of parathyroid hormone.

The parathyroid hormone concentration in the blood measured by the 'two-site radioimmunoassay', which is specific for the biologically active parathyroid molecule (parathyrine), was compared with the radiological manifestations of secondary hyperparathyroidism (HPT) on magnification radiographs of the phalanges in patients undergoing maintenance hemodialysis and in patients with renal allografts. Sensitivity of radiology for the diagnosis of HPT proved to be high (88%), whereas specificity was low (30%). Statistical analysis showed that there was a good correlation between the parathyrine levels and the intensity of radiological changes in the phalanges in patients with renal allografts (coefficient of Krueger-Spearman = 0.65). In patients undergoing hemodialysis the correlation between laboratory parameters and radiological changes was poor.

[Color-coded Doppler sonography in the diagnosis of carotid artery diseases]. / Farbkodierte Dopplersonographie in der Karotisdiagnostik.

Color-flow Doppler is a new development of duplex sonography of the peripheral vessels. In this study 844 consecutive patients were evaluated (a) to assess the comparative value of these two methods, (b) to see if there is a correlation between the degree of stenosis and the incidence of neurological symptoms and (c) to find a possible relationship between the plaque structure and the incidence of neurological deficits. (a) In 89%, the color-flow assessment was in complete agreement with the duplex assessment. In the remaining 11%, important additional results were discovered in the color flow examination. (b) Non-stenotic plaques were seen more often (43%) in the wide carotic bulb, stenotic plaques and occlusion were found more often (66 and 82%) in the internal carotic artery. Vessel occlusion was found most often in patients with cerebral ischemia. Color-flow Doppler demonstrated a higher incidence of hemodynamic stenosis in patients with peripheral vascular disease, hypertension and bruits. (c) Patients with heterogeneous plaques demonstrated a significantly higher risk of neurological deficits than those with homogeneous plaques. The great advantage of color-flow Doppler is that it enables sonomorphological (plaques, stenoses, occlusion) and functional parameters (turbulences, flow enhancement) to be studied during the same procedure.

Jogging causes acute changes in the knee joint: an MR study in normal volunteers.

As MR imaging allows evaluation of soft-tissue structures not previously possible with imaging techniques, we undertook a preliminary study to evaluate the effects of a popular form of exercise (jogging) on the knee. The specific question prompting our investigation was, does repetitive impulse loading produced by jogging cause acute structural changes within the knee that are visible by MR imaging? The knees of 10 healthy subjects were examined on a 1.5-T MR system before and immediately after 30 min of continuous jogging. The same extremity was examined each time, and the imaging sequences and photographic technique (meniscal windows) were identical for both examinations. Effusions developed in five of 10 subjects after exercise. In addition, five of 10 subjects had subtle increased signal intensity within their menisci. These results suggest that jogging frequently leads to acute changes in the knee that are visible on MR imaging. The significance of these changes is unknown.