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Aim of this study was to assess the value of Gd-DTPA administration in MRI of cervical disk herniations. In 34 patients, showing 40 cervical disk herniations, plain proton density- and T1-weighted as well as contrast-enhanced T1-weighted 2D-FLASH images were generated. Contrast between the herniated material and the CSF already was sufficient without administration of Gd-DTPA in all cases. Sufficient contrast between the herniations and the intraforaminal structures was obtained in 13/40 cases and 40/40 cases on plain and contrast-enhanced images, respectively. Definition of the herniated disks was judged to be sufficient in 30/40 cases on plain images and 40/40 cases on contrast-enhanced images. The diagnostic value of the images was improved in 3/12 lateral and 7/8 intraforaminal herniations by contrast administration, whereas there was no significant increase in diagnostic value in posterior or posterolateral herniations. As a result, Gd-DTPA administration is recommended if definition of lateral and intraforaminal disk herniations in MRI is poor.

MR images of 48 patients with histologically confirmed benign and malignant diseases of the pleura were retrospectively compared with CT and bioptically/surgically obtained findings. In 47/48 patients pathological changes of the pleura were visualized by increased signal intensities on T2-weighted and contrast enhanced T1-weighted MR images. This lead to a slightly improved sensitivity compared to CT, where pathological pleura findings were confirmed in 45/48 patients. MRI was able to identify 24/28 confirmed pleural effusions, whereas CT was successful in 26/28 patients. In two cases effusions not identified on CT were visible on T2-weighted MRI. 4 pleural effusions were missed with MRI.. On CT images differentiation of pleural changes vs effusions or adjacent lesions of lung parenchyma was successful in 20/28 and in 17/23 cases, respectively. Contrast enhanced T1-weighted images achieved the highest diagnostic accuracy with 22/28 and 20/23 cases, respectively. Signal intensities on MRI were unsuitable as sole criterion for the differentiation of benign and malignant diseases of the pleura. Contour and pattern of spreading of pleural changes were helpful in differential diagnosis. Nodular changes, thickening of more than 10 mm and mediastinal, circumferential and entire hemithoracic affection of the pleura were suggestive for malignant pleural disease. Infiltration of the diaphragm and the chest wall were most indicative for malignancy; here MRI (2/2 resp. 18/19 cases) was superior to CT (0/2 resp. 14/19 cases). CT was superior in the detection of pleural calcifications and osseous destruction.(ABSTRACT TRUNCATED AT 250 WORDS)

We compared the value of gadolinium-enhanced first-pass MRI perfusion studies and HMPAO-SPECT for the assessment of regional cerebral blood flow in a prospective study of 23 intracranial tumour patients. In five tumours with homogeneous hypoperfusion and eight tumours with homogeneous hyperperfusion, tumour blood flow patterns in MRI and HMPAO-SPECT were similar. By contrast, in ten patients with inhomogeneous tumour blood flow pattern only MRI was able to differentiate between tumour areas with no or low flow, tumour tissue with high flow, and perifocal oedema with reduced flow. In HMPAO-SPECT, these inhomogeneous tumours were represented as areas of homogeneously reduced tracer retention corresponding to different tumour constituents and perifocal oedema. In conclusion, the high spatial resolution of MRI enables a detailed analysis of tumour blood flow.

A prospective study was carried out involving 27 patients to determine whether MRT can distinguish between lymph node metastases and reactive lymph node enlargement. The results of MRT were compared with the pathological findings. Using T1 and T2 weighted sequences and proton density sequences it was not possible to differentiate between reactively enlarged lymph nodes and lymph node metastases. Following the administration of Gd-DTPA the observation of central hypo-intensity with marginal hyper-intensity is a reliable sign of a lymph node metastasis. Using the criterion of length greater than 10 mm for lymph node metastases results in a specificity of 32% and sensitivity of 75%. The use of the sonographic maximal/cross measurement quotient > 2 in the axial/coronary/sagittal dimension improves specificity and sensitivity to 94%.

MR imaging of the orbits was performed in 59 patients with untreated Graves' ophthalmopathy (follow-up exams were performed in 11 patients). T2-relaxation times of eye muscles were calculated and correlated with duration of disease. Elevated T2 times indicating eye muscle edema were found even if ophthalmopathy had been existing for more than one year. MRI documented specific eye muscle changes and transformation of oedema to fibrosis and fatty degeneration. MRI thus allows for standardized planning of therapy and follow-up in patients with Graves' ophthalmopathy.

The MRI and CT appearances in 48 patients with histologically confirmed benign and malignant pleural abnormalities were compared retrospectively. Abnormal pleural changes were shown in 47 out of the 48 patients by high signal intensity of the pleura in T2-weighted sequences and in contrast enhanced T1-weighted sequences on MRI. CT showed abnormalities in 45 out of 48 patients. Delineation of pleural and pulmonary changes by CT was possible in 13 out of 23 cases, and pleural disease from effusions in 15 out of 28 cases. T2-weighted MRI was successful in 14 out of 23 and 4 out of 28 cases, respectively. T1-weighted images after contrast were successful in 20 out of 23 and 22 out of 28 cases, respectively. Indications of malignant pleural disease were the presence of mediastinal or circumferential involvement or involvement of the entire pleura, thickness of more than 10 mm and nodular changes. The most reliable sign of malignancy was infiltration of the thoracic wall and the diaphragm; this was better demonstrated by MRI (18 out of 19 and 2 out of 2 cases) than by CT (14 out of 19 and 0 out of 2 cases).

The MRT and CT images of histologically confirmed intracranial ependymomas in 10 patients have been compared. All tumours were demonstrated by CT and MRT. The solid portions of the tumours showed variation in density on CT (hypodense, isodense, hyperdense, or mixed), whereas there was uniform signal intensity on MRT (T1 weighted: hypointense, T2 weighted: hyperintense). Cystic portions of the tumours (6 patients) were shown equally well by both procedures, calcifications were only shown by CT. All ependymomas were related to the ventricles. On unenhanced CT only 3 tumours were clearly delineated, whereas MRT defined all tumours satisfactorily. The significant advantage of MRT is better topographic demonstration of the tumour.

MR imaging was performed in 19 patients with proven multiple myeloma. Both plain and Gd-DTPA enhanced in-phase and opposed-phase gradient-echo techniques were used (0.1 mmol Magnevist/kg body weight). Plain, opposed-phase imaging demonstrated more lesions than plain in-phase imaging (35 vs. 16); enhanced opposed-phase imaging demonstrated more lesions than plain opposed-phase and enhanced in-phase imaging (47 vs. 35 and 17 lesions). These results suggest that enhanced opposed-phase images which have a high contrast between normal and infiltrated bone marrow are especially suited for MR screening in multiple myeloma.

The aim was to validate the MRI assessment of regional cerebral blood flow. Measurements were performed on a 1.5 T imaging system using a fast T2*-weighted gradient-echo sequence. After intravenous injection of gadolinium-DTPA 30 images were acquired in the same slice position during 84 seconds. In 12 volunteers we observed a symmetrical cortical decrease of signal intensity during the passage of the contrast medium. In 9/23 patients with impairment of cerebral blood flow a circumscribed area of reduced signal intensity decrease (hypoperfusion) was found. In 4/23 patients the decrease of signal intensity was more pronounced than in normals (hyperfusion). In 9/23 patients signal intensity changes were normal. HMPAO-SPECT confirmed successful MRI assessment of cerebral blood flow in 22/23 patients.

In a group of 25 patients the coronal views of plain and Gd-DTPA-enhanced MRI studies were correlated with CT and operative findings. All series included sagittal, transverse and coronal FLASH sequences (GE 500/6, flip angle 70 degrees), sagittal proton density-(SE 2500/15) and T2-(SE 2500/70) weighted images. MR diagnosis proved to be correct in all cases. Compared to CT and axial MRI herniated disk material in the lateral intravertebral space and its relationship to nerve roots was demonstrated more clearly on coronal views.

MR and CT examinations of 16 patients with lymphoma, pseudolymphoma and inflammatory pseudotumours were analysed to describe morphologic features of lymphocytic infiltration. Density and signal did not allow for differentiation, but localisation was the most important criterion: lymphoma and pseudolymphoma were located in the anterior superior orbit, inflammatory pseudotumours being retrobulbar lesions. Differentiation is of clinical importance, since both lymphoma and pseudolymphoma are accompanied by generalised malignant lymphoma while inflammatory pseudotumours are localised. Imaging of topographic relations of lens, optic nerve and lesion on sagittal MR images was found helpful for radiation therapy planning.

In the present study the influence of the flip angle on image contrast in spin echo imaging was investigated. It was evaluated, whether variation of the flip angle allows for shorter repetition and imaging times in T2-weighted spin echo sequences. 10 patients with cerebral white matter lesions were investigated with an 1.5 Tesla whole body tomograph using a conventional double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and time-optimized double-spin echo sequences (TR = 1900 ms, TE 15 and 70 ms) at flip angles of 90, 80, 70, 60 and 50 degrees. A reduction of the flip angles resulted in a decrease of T1-weighting and a relative increase of T2-weighting of the images. Despite the reduced repetition time at a flip angle of 70 degrees visually and quantitatively assessed contrast between lesions and brain as well as image artifacts of the time-optimized sequence were comparable to the conventional spin echo sequence; however, imaging time was shortened about 25%.

We studied first-pass MRI contrast dilution to compute flow and volume of distribution in a realistic flow phantom. Pulsatile flow was provided by a one-chamber artificial heart. Physiological stroke volume, rate, pressure, and flow were adjustable. An elastic tube with dimensions similar to that of the human aorta was imaged at a rate of 2.4 Hz. After contrast injection, an initial increase in signal intensity was followed by a decrease. Signal-intensity time plots demonstrated slightly skewed curves as expected from dispersion theory. After calibration at different gadolinium-DTPA concentrations, signal intensities were converted into true gadolinium concentrations, and flow was calculated from the concentration-time curves. Flow was varied between 2.5 and 10.0 l/min and a significant correlation was found between the MRI estimate and true flow. Volume of distribution between injection and detection site was reliably estimated. This study demonstrates rapid 2-D imaging of a paramagnetic contrast bolus in a realistic flow phantom. Reliable estimates of flow and volume are obtained.

Anatomical specimens and normal persons were studied by gradient echo MR imaging to determine the influence of different echo times (TE) on bone marrow contrast. First of all, six normal persons were studied to determine specific echo times for in-phase and opposed-phase states. Using different sequences bone marrow contrast in isolated femoral bones was determined and compared to results of pathological exams. Red bone marrow had no signal on opposed-phase images; contrast between red and yellow marrow was higher on opposed-phase than on in-phase images. Bone marrow lesions can be expected to be visualised with high signal on opposed-phase images; this technique should be especially suited for MR imaging of bone marrow.

Differentiation between liver metastases and local fat deposition may be difficult when using CT; the value of MRI was therefore investigated in 18 patients with metastases and ten patients with fat deposits. CT shows both lesions as similar hypodense areas. MRI, however, produces different appearances: T1- and 2-weighted images show marked differences in the signal arising from metastases, whereas local fat collections in both sequences differ little in their signal from normal liver. Quantitative MRI signal intensity of the two types of lesion were also different. Where the differentiation by CT may be difficult, it may be made with certainty by means of MRI.

The effect of various factors on the demonstration of calcified lesions was studied in 131 areas of calcification which had been demonstrated by CT. By means of MRI (SE 400/30 or GE315/14, 90 degrees and SE 1600/30 + 70; 0.5T) 117 of the 131 calcified lesions (89%) produced a signal difference. Of these 117 lesions, 80 (61%) were recognised as calcification by MRI. Large areas of calcification (more than 5 mm) and high density calcification (more than 100 Hu) were recognised significantly more often than small or low density calcifications. T2-weighted images demonstrated calcification more often than other sequences. With conventional pulse sequences, calcified lesions were frequently recognised as abnormalities on MRI, but their recognition as calcified lesions is unreliable.

Coronal T2-weighted MRI is the most sensitive imaging modality to detect temporal lobe pathology. However, prepontine artifacts resulting from pulsation of cerebrospinal fluid occasionally simulate temporal lobe lesion. To characterize this artifact we studied 30 patients without temporal lobe pathology in conventional T2-weighted spin-echo technique (0.5 T, SE 1600/70, coronal, horizontal phase encoding). Visual analysis revealed high-intensity artifacts simulating a lesion in five of 30 cases. The present study shows that prepontine artifacts due to pulsation of cerebrospinal fluid are quite frequent (17%) and that these artifacts may result in misinterpretation in the evaluation of temporal lobe epilepsy. By a repeat examination in identical methodology while using vertical phase encoding, all artifacts could be identified and an artifact-free representation of the temporal lobes was achieved.

A study has been carried out to evaluate contrast and image quality of cervical structures using multislice 2D-flash sequences with long repetition times (TR = 400 ms.) and short echo delay times (TE = 5.8 ms.). The examinations were carried out using ten normals with an MRI of 1.5 Tesla and flip angles of 10, 20, 30, 50, 70 and 90 degrees. The best contrast between intervertebral disc and surrounding tissue was obtained between 50 and 70 degrees, best contrast between compact bone and CSF with 10 degrees. In order to demonstrate degenerative changes of the cervical spine, it appears sensible to use a combination of these angles. The described sequences produce good images of the cervical structures with little image degradation. Compared to T1-weighted spin-echo sequences, the method has a number of significant advantages, such as variations in image contrast, higher maximal number of slices, contiguous imaging and less imaging time.

Sensitivity and specificity of plain T2-WI and Gd-DTPA enhanced T1-WI were compared by evaluating MR exams of 30 patients with brain metastases. Large lesions with high signal on T2-WI always enhanced (43/43) when a structure (perifocal edema, tumor tissue, central necrosis) was found. Large lesions nearly always enhanced (53/55) even if no such structure was found. 65% of small unstructured white matter lesions with high signal on T2-WI, which are generally considered vascular, did not enhance. Surprisingly, 35% did enhance. Demonstration of blood brain barrier disturbance in these lesions suggested a metastatic origin. In 3 patients with multiple metastases, Gd-DTPA enhanced T1-WI disclosed more than 140 lesions not seen on T2-WI. All of them were located in or adjacent to grey matter. Our results indicate that enhanced T1-WI should be obtained even if T1-WI are normal or show only small white matter lesions.

We studied 129 AIDS patients with suspected or proved intracranial manifestations of the disease. The purpose of this study was to compare the diagnostic sensitivity of unenhanced and contrast enhanced CT and unenhanced T2-weighted MR. In 35/129 patients CT and MR findings were normal. In 37/129 patients equivalent findings were obtained with both methods. Although CT and MR demonstrated intracranial pathology in 25 cases, MR was clearly superior. Six of these cases had solitary lesions in CT, while MR demonstrated multiple lesions. MR detected more foci than CT. In 24 patients with normal CT, MR detected intracranial manifestations of AIDS, namely solitary lesions in 8, multiple lesions in 12 and meningeal alterations in 4 patients. In only 8 patients with normal MR findings, CT revealed pathological contrast enhancement in 2 and parenchymal calcifications in 6 patients. Thus, in 20% of our patients MR but not CT was diagnostic. In another 20% MR provided additional diagnostic information. In conclusion, MR is recommended as the imaging modality of choice in AIDS patients with non-conclusive cranial CT.

The diagnostic value of various doses of Gd-DTPA was compared intra-individually. Thirty-three patients with cerebral tumours were randomly allocated to three groups. Group 1 was given a dose of 0.025, group 2 a dose of 0.05 and group 3 a dose of 0.1 mmol GD-DTPA/kg body weight. Following administration of Gd-DTPA the average tumor/brain contrast in group 1 was -4.5%, in group 2 +8.4% and in group 3 +43.0%. Diagnostically useful tumour delineation was obtained in two out of 11 in group 1, in seven out of 11 in group 2 and in 10 out of 11 in group 3. A further increase in the dose to 0.2 mmol/kg body weight in group 3 resulted in a further increase in tumour/brain contrast of +62.5% and improved tumour delineation in one case. As a result of these findings a dose of 0.1 mmol Gd-DTPA/kg body weight is recommended for the routine investigation of intracranial tumours.

In 50 patients with Graves' Ophthalmopathy and 9 controls both orbits were examined by MR Imaging at 0.5 Tesla using a surface coil. T1-weighted spin-echo images were obtained in transverse and coronal orientation; additionally, a T2-image was calculated from a multi-echo sequence (8 echoes). Signal intensity of eye muscles on both T1-weighted and T2-weighted MR images was evaluated qualitatively. T2-times were then calculated for all inferior rectus muscles. Eye muscle enlargement was found in 28 out of 50 patients. T2-times of inferior rectus muscles in stage III and IV patients were evaluated significantly (p less than 0.05). Areas of high signal intensity were accordingly found in enlarged eye muscles in 19 out of 50 patients; they were interpreted as edematous tissue changes. Areas of low signal intensity were found in enlarged eye muscles of 5 out of 50 patients; these eye muscles were considered fibrotic. Differentiation of eye muscle changes by MR imaging might help to decide between antiinflammatory medication and surgical therapy in patients with Graves' Ophthalmopathy.

Twenty-two patients with intrathoracic malignancies and suspected Pancoast and "break-out" tumours were submitted to a comparative investigation using CT scanning and MRI to detect infiltration of the chest-wall. In the patients, the lesion had been confirmed at surgery, which revealed malignant infiltration in 19 cases, and excluded in filtration in 3 cases. In 14 out of 19 patients, the CT scan revealed tumourous involvement of the chest-wall, while in five out of 19 patients, no such involvement was detected. Using MR imaging, tumour infiltration was detected in all 19 patients. A reliable MR sign of tumour involvement was the detection of signal-intensive lesions within the chest-wall in T1-weighted images following the administration of Gd-DTPA, and in the T2-weighted images. In contrast, signal enhancement of the pleura was found both in tumour involvement and in inflammation. In suspected tumorous chest-wall invasion MR imaging can demonstrate tumour involvement of the chest-wall when CT is equivocal.

A comparative study between magnetic resonance tomography (MRT) and CT was carried out in 16 patients with temporal lobe epilepsy. The MRT studies were performed on a 0.35 T Magnetom with T.1 modes in a coronal plane. MRT proved to the superior to CT. CT demonstrated a discreet temporal lobe lesion in three patients and MRT in four patients. In addition, unilateral atrophy of the temporal lobe was demonstrated by MRT in six cases; these could not be diagnosed by CT. The lack of artifacts near the skull base, the possibility of producing coronal sections and the excellent tissue differential of MRT provide the basis for improved diagnosis of lesions in the temporal lobes.

Intravenous digital subtraction angiography has been employed to examine arteries in 600 patients. Conventional angiography was used in 41 cases where insufficient DSA was made, or as definitive preoperative investigation. In 88% the digital subtraction angiogram is diagnostic, and conventional angiography then shows little more additional information.

The value of CT and MR was studied in 100 patients with temporal lobe epilepsy. Axial CT scans were obtained before and after contrast injection. Coronary MR scans were carried out with T1-(SE 400/30, GE 315/14) and T2-weighted sequences (SE 1600/30 + 70). A circumscribed lesion was demonstrated in fifteen patients by CT and in 25 patients by MR. With the exception of a small area of calcification, all lesions seen on CT could also be recognized on MR. In four patients CT, MR and pathologic specimen could be compared following partial resection of temporal lobe. Localized glial reactions, which were not seen on CT, produced a signal difference on MR. Better sensitivity and improved demonstration of the temporal lobes makes MR the method of choice in the diagnosis of temporal lobe epilepsy.

The MRI findings in 26 patients with primary syringomyelia and eight patients with a syrinx due to an intramedullary tumour were studied retrospectively. In general, the syrinx in the tumour cases resembled the appearance of primary syringomyelia. However, a specific and sensitive sign of tumour-induced syringomyelia was irregularity of the spinal cord close to the tumour (eight cases of eight), eccentric position of the lumen (seven of eight), and a diffuse increase of signal intensity on T2-weighted images (eight of eight). Primary syringomyelia also showed increased signal intensity on T2-weighted images outside the lumen, but this was closely related to the cavity. The use of Gd-DTPA improved demarcation of the tumour from the syrinx in all cases. Widening of the spinal canal and ectopia of cerebellar tonsils was a typical finding in primary syringomyelia. MRI proved a reliable method for distinguishing between a tumour-induced syrinx and primary syringomyelia.

The MR appearance of normal and pathological meninges was studied in 23 patients. Amongst twelve normals, T1-weighted images demonstrated the meninges as slightly hyperintense density structures (compared with CSF) which increased in signal intensity somewhat after the administration of gadolinium-DTPA. On T2-weighted images, the subarachnoid space and meninges were isointense. In eleven patients with inflammatory disease or tumourous infiltration of the meninges, abnormal findings were evident in the unenhanced images as well as after administration of gadolinium-DTPA. Compared with CT, MR proved greatly superior in the diagnosis of meningeal abnormalities.

Bone scintigraphy of the sacroiliac joints and the lumbar spine was performed in 35 patients with ankylosing spondylitis and 30 control subjects. The scans were evaluated by qualitative and quantitative assessment. The sacroiliac/sacrum ratio (index ISG/sacrum), the sacroiliac/lumbar spine ratio (index ISG/LWS), and the left sacroiliac joint/right sacroiliac joint ratio (index li. ISG/re. ISG) were calculated. The visual interpretation of colour scans proved to be unreliable. The index ISG/sacrum was more sensitive than the index ISG/LWS. The index li. ISG/re ISG was helpful as an additional criterion. When digital sacroiliac joint scintigraphy is well standardized it can be considered as a useful technique in early diagnosis of ankylosing spondylitis.

In an initial clinical trial we examined the tolerance and the influence exercised on signals in nuclear magnetic resonance tomography by gadolinium-DTPA. In an open study, 4 dosages between 0.005 and 0.25 mmol Gd-DTPA/kg body-weight were tested on 5 healthy volunteers each. To ensure renal elimination of Gd-DTPA, NMR images were produced (0.35 T Magnetom) visualising the kidneys and urinary bladder before and more than 60 minutes after application of the contrast medium. The article shows in what manner the image is influenced by the dosage of the contrast medium and also by the time interval elapsing between injection of the contrast medium and production of the NMR tomogram. - Finally, first clinical results of NMR tomography contrast medium application are demonstrated in the case of 5 patients with cerebral tumours.

The principles underlying contrast media for MR tomography are totally different from those for conventional contrast media. Substances suitable for MR tomography are paramagnetic complexes which alter the relaxation times of the tissues. Signal intensity on the MR images are influenced correspondingly. The mode of action of MR contrast media is explained. Gadolinium-DTPA, the first MR contrast medium in clinical use by means of intravenous injection, is described. Its tolerance has been investigated by animal experiments and its effectiveness as an contrast agent has been studied in normal individuals. In the second part of the paper, early results from the use of gadolinium DTPA are given. The additional information which can be obtained by using MR contrast media is discussed.

The association between acute iridocyclitis (a.i.) and sacroiliitis/ankylosing spondylitis is well known. Since bone scintigraphy is a sensitive method of detecting sacroiliitis before radiologic evidence of this condition appears, we examined the role of scintiscanning in the investigation of sacroiliitis in patients with a.i. The sacroiliac-joint/sacrum ratio was determined in 30 control subjects and in 21 patients with a.i., who showed no radiologic signs of sacroiliitis. No discrimination between patients with a.i. and control subjects was obtained by scintigraphy, neither did we find any difference in the mean sacroiliac-joint/sacrum ratios between HLA-B-27-positive and HLA-B-27-negative individuals with a.i. This study does not support the claim that patients with a.i. often suffer from clinically and radiologically silent sacroiliitis which would be detected only by scintigraphy. According to our results, regular scintigraphic examinations of the sacroiliac joint in all patients with a.i. are not indicated.

Intravenous digital subtraction angiography (DSA) was obtained in 55 cases after reconstructive procedures of the carotid arteries, the pelvic and lower limb arteries. In 48 cases (87%) the studies were of technically satisfactory or good quality. On DSA 32 vascular reconstructions were normal and 16 had typical complications like occlusions, stenoses, aneurysms and insufficient run-off. -Experience indicates that the spatial resolution of DSA is adequate for clinical purposes such as determining graft patency or the presence of postoperative complications. Because DSA is less invasive than catheter angiography, postoperative evaluation of patients having undergone peripheral surgical revascularization should start with DSA.

This study examines the effect of the NMR contrast medium gadolinium-DTPA on image contrast in cerebral tumours. Sixteen patients with space-occupying cerebral lesions were examined on a 0.35 Tesla superconducting scanner, using a T1-weighted spinecho sequence prior to and after the intravenous application of gadolinium-DTPA. In 8 patients T2-weighted spinecho-sequences were obtained before the administration of contrast. The tomograms were evaluated visually and according to quantitative criteria. The use of gadolinium-DTPA helps to evaluate the blood-brain barrier and improves diagnosis by differentiating tumour tissue from edema and from normal brain tissue.

Thirteen patients with a clinical diagnosis of syringomyelia were examined by nuclear tomography (0.35 T magnet) in the spin-echo mode. In all thirteen patients, the T1 images (SE 400/35) showed a longitudinal cavity with a signal intensity of CSF. The shape and extent of the syrinx could be adequately demonstrated in 12 of the 13 examinations. Downward displacement of the cerebellar tonsils was seen in eight cases. The examination took between half and one hour. Advantages of magnetic resonance tomography (nuclear tomography) include the absence of artifacts, images in the line of the lesion and its non-invasiveness.

Thirteen patients with aortic aneurysm (abdominal 7, thoracic 4, thoraco-abdominal 2) were evaluated by magnetic resonance tomography using a super-conducting magnet of a field strength of 0.35 tesla in transversal, coronal and sagittal planes. ECG gating was used in patients with thoracic aneurysm. The results of magnetic resonance imaging (MRI) were compared to angiography, computed tomography (CT) and intraoperative findings. MRI demonstrated in all 13 patients the extent and the localisation of the aneurysm. The presence of mural thrombus was better determined by MRI (10/10) than by angiography (6/10). The relationship of the brachiocephalic arteries in thoracic aneurysm was better evaluated by MRI compared to angiography and CT. All 3 aortic dissections could be demonstrated by MRI. These first results may suggest an important role of MRI in the diagnosis of aortic aneurysms.

CT and MRI were performed on 19 patients with pleura related thoracic tumors with respect to the detection of chest-wall invasion. All patients underwent surgery, which confirmed malignant infiltration in 16 cases, while this was excluded in three. CT showed chest-wall invasion in 12/19 patients. MRI demonstrated tumorous involvement in 16 patients. A reliable pattern of chest-wall invasion in MRI were high signal intensity lesions within the chest-wall in the T2-weighted images. However, increased signal intensity of pleural structures was found in inflammatory as well as in malignant lesions. MRI can prove the presence of chest-wall invasion when CT is equivocal.

The early results of the use of the MR specific contrast medium gadolinium-DTPA in 40 patients with intracranial tumours are reported. Optimal pulse sequences, contrast dose and timing are discussed. The relationship between the blood-brain barrier and contrast distribution within tumour tissue is elaborated. The clinical significance of the application of contrast agents in the diagnosis of brain tumours is evaluated.

Twelve patients (average age 40 +/- 15 years) with impotentia coeundi were angiographically examined under suspicion of a vasculogenic impotence. Overview angiographies of the pelvis and selective iliaca interna injections were performed. The normal anatomy of the pudendal artery and the penile branches is shown. Ten patients were suffering from a stenosis or total occlusion of the dorsal pudendal artery, the dorsal penile artery or the profound penile artery with or without filling of a peripheral segment. The role of arteriography in surgical treatment is discussed.

After in-vivo labeling of red blood cells with 99mTcO4, the radioactivity of different parts of the body is proportional to the regional blood volume. This technique allows the simultaneous registration of drug-induced changes of the local blood volume. We examined the influence of nitroglycerin on the blood volume distribution in patients with coronary artery disease (n = 10) and chronic heart failure (n = 8). Compared with the controls (n = 8) we observed in the nitroglycerin-groups a significant decrease of blood volume over the heart and the liver, whereas there was an increase of the blood volume over the extremities. It is pointed out that functional whole-body scanning is a useful radiological technique for the non-invasive study of pharmacologically caused changes of the local blood volume in man.

Quantitative sacroiliac scintigraphy was performed in 41 patients with ankylosing spondylitis (Sp.a.) and in 90 control subjects. The sacroiliac/sacrum ratio (Index ISG/sacrum) was calculated. We examined the correlation between activity ratio on the one hand and age, subjective complaints, erythrocyte sedimentation rate, and antiinflammatory therapy on the other. Significantly increased uptakes were found in the patient group as a whole compared with the controls. The activity index was highest in the early periods of the disease, so we conclude that scintigraphy is useful in the early diagnosis of Sp.a.

The MR results in 21 patients showing the initial manifestations of multiple sclerosis (MS) were compared with those in 45 patients with a long history of MS. As in the old cases, MR proved a very sensitive technique during the early manifestations, with abnormal findings in 20 out of the 21 patients. The relatively characteristic MR findings in long-standing MS (predominant peri-ventricular involvement with a relatively typical pattern) was seen in the early stages is only rare cases. The value of MR during the initial manifestations of MS is in cases where the clinical findings are not conclusive and laboratory diagnosis (evoked potentials, CSF findings) are indefinite. In these patients the findings of multiple lesions in the brain can confirm the suspected diagnosis of MS.

A comparative study, on 251 patients, between CT, Octoson and conventional ultrasound, established that CT (with angio-CT) had the highest rate of sensitivity (95.86%). The Octoson examination had a higher sensitivity (92.58%) than the conventional ultrasonic examination (82.64%). This result is achieved because superficial and subdiaphragmatic metastases, which lie in the depth of the liver, are better presented by the Octoson than with a mechanical sector scanner. Superficial metastases need to be presented with a water-path transducer for superficial lesions and subdiaphragmatic metastases with a wide range focus transducer. These areas can also be accurately shown on scanners with a dynamic transducer. The specificity of these three methods lies between 90 and 96%.

Twenty-three patients with intra cranial meningiomas were examined by means of magnetic resonance tomography (MRT). In 13 patients the paramagnetic contrast medium gadolinium DTPA was used. Meningiomas show only slight changes in signal intensity compared with brain in the spin-echo mode, the greatest contrast being found on photon density images (TR 1600 ms, TE 35 ms). In T1 images, more than 50% patients showed a low signal margin between tumour and brain, Hyperostosis of the calvarium is easily recognised, but MRT is unreliable for showing tumour calcification. After intravenous injection of gadolinium DTPA, there was marked homogeneous uptake in the meningiomas. These signs are useful for the diagnosis of a meningioma by MRT.

The current paper is a review of our experience of 1200 examinations of the brain, using magnetic resonance tomography (MRT), derived from a mixed neurological and neuro-surgical clinic. MRT has advantages in localisation and tissue characterisation. Localisation is improved by the ability to obtain coronal and sagittal images and by the absence of artifacts due to bone in lesions in the middle and posterior fossa. Some tissues and structures (blood, fat, vessels) produce relatively characteristic signals on MRT, which may be important in clinical diagnosis (eg. chronic subdural haematoma). A significant advantage of MRT is its excellent contrast resolution of soft tissues; this results in better demonstration of normal brain anatomy (eg. corticomedullary contrast), areas of demyelinisation (eg. multiple sclerosis) and certain cerebral tumours (eg. astrocytomas). On the basis of our experience, certain indications are defined, depending on the physical characteristics of the method; these are illustrated by clinical examples.

The kidneys in 15 patients (8 renal tumours, 4 cysts and 7 normal patients) were examined by means of super-conductive NMR tomography in order to assess the value of the method and its use in tumour staging. The findings were compared with computed tomography, angiography and surgery. Parenchymal tumours and cysts are easily recognised and differentiated, as they are on CT. NMR demonstrates a pseudo-capsule, which can otherwise only be seen on the angiogram, or on angio-CT. The extent in the peri- and pararenal space, infiltration into neighbouring organs and lymph nodes are equally well seen on NMR and CT. NMR equals angiography for demonstrating invasion into the renal vein and vena cava and, in this respect, is better than CT.

In 35 patients with recurrent radicular complaints which occurred 4 weeks to 38 months after operation for lumbar disc herniation, the degree of contrast enhancement of hypertrophic scar tissue was examined. All patients were scanned before and immediately after intravenous contrast application (volume: 1.5-2.0 ml/kg body weight, flow rate: 0.35 ml/sec). In 83% of the cases hypertrophic scar tissue did show definite contrast enhancement, whereas disc herniation remained unenhanced. Comparison between contrast enhancement and age of scar tissue produced poor correlation (r = 0.3012) with older scarring showing a trend towards lower enhancement levels. In cases where morphologic and topographic criteria in plain CT examination fail to yield a diagnosis, intravenous contrast application is recommended. Our data indicate that even those patients might benefit from the procedure who have been operated upon for disc herniation several months or years ago.