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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.

In 36 patients with intracranial tumors, gadolinium (Gd)-DTPA-enhanced SE 400/35, SE 800/35 and IR 1500/400/35 sequences were intraindividually compared. Contrast enhancement usually was shown to better advantage with the IR sequence. Post-contrast SI of tumor tissue was isointense with white matter on IR images in many cases whereas SE sequences displayed enhancing tumor with high contrast versus brain. Post-contrast tumor delineation, therefore, was better with the SE sequences especially in white matter lesions without perifocal edema. The SE 400/35 sequence which allows for contrast-enhanced MRI within a relatively short time is suggested for Gd-DTPA studies of brain tumors.

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.

Quantitative sacroiliac scintigraphy was performed in 33 patients with ankylosing spondylitis (AS), 34 patients with nonspecific low back pain, and 30 control subjects. Significantly increased uptakes over the sacroiliac joints (SIJ) were found in patients with AS and in patients with degenerative changes of the SIJ. No significant differences were found between patients with mechanical low back pain by lumbar strain or by degenerative changes of the lumbar spine and the control subjects. But there were 2 of 13 patients with low back pain by lumbar strain with pathologic uptakes over the ISG. Since the scintigraphic technique is not specific, it is necessary to compare the scintigraphic results with clinical and radiological findings in each patient. On this condition sacroiliac scintigraphy is useful in early diagnosis of AS.

The electroencephalograms of 40 patients with acute symptoms of multiple sclerosis, 10 of whom presented with primary manifestation, were compared with the findings in cerebral nuclear magnetic resonance imaging. 32.5% of the patients EEGs showed abnormalities. Considering borderline findings the percentage of remarkable EEGs mounted to 60%. All of the patients presented periventricular lesions in NMR. In addition to the periventricular abnormalities between 1 and 26 district lesions per patient were found (mean = 6.5; Median = 5). In the patients group with five and more non-periventricular lesions, there were significantly more pathologic EEG-findings (p less than 0.05) than in the group with fewer lesions. Statistical correlations between EEG-abnormalities and the extent of functional deficit could not be substantiated. Neither could type and locality of EEG-changes be correlated to non-periventricular lesions in NMR.

The dimeglumine salt of the Gd-DTPA complex has a strong paramagnetic effect and a very low toxicity in animals. This report of its use in human volunteers confirms its low toxicity and indicates its usefulness in the enhancement of signal intensity of the kidney and bladder.

61 patients with suggested pancreatic disease were examined by Hypotonic Duodenography (HD) and Computed Tomography (CT). After all examinations had been carried out, 45 patients were found to have an abnormal pancreas, and 16 patients had a normal pancreas. HD had a sensitivity of 60%, and a specificity of 94%, whereas CT had a sensitivity of 78% and a specificity of 100%. - HD is more sensitive than CT in detecting lesions originating from pancreatico-duodenal structures. In patients with uncertain clinical symptoms of the upper gastrointestinal tract HD is still a valuable basic examination. Only in patients with strongly suspected pancreatic carcinoma radiologic examination should start with CT because CT is more sensitive in detecting a pancreatic lesion and is helpful in assessing its extension and defining its etiology.

Time-dependent changes in the contrast enhancement of tumor tissue, tumor necrosis, perifocal edema, and normal brain tissue after IV injection of 0.1 mmol gadolinium-DTPA/kg body weight were studied with spin-echo technique (SE 800/35) in 15 patients with intracranial tumors. Using a region of interest technique, we determined the signal-intensity values of these tissues before and at fixed times up to 68.5 min after administration of the contrast agent. In tumor tissue, the 8.5 min postinjection (p.i.) scan showed a significant increase in signal intensity. The signal intensity of the tumor tissue remained significantly higher than precontrast levels throughout the entire period of observation, decreasing only slightly toward the end of the examination (48.5 and 68.5 min p.i.). Central tumor necrosis exhibited a delayed uptake of the contrast agent, with a maximum signal intensity between 48.5 and 68.5 min p.i. In perifocal edema and normal brain tissue, slight increases in signal intensity after injection of gadolinium-DTPA were measured (statistically significant in the case of edema). This effect, however, was not visually detectable. The present study shows that after one injection, scans with excellent tumor visualization can be obtained between 8.5 and 38.5 min p.i. and with diagnostically valid enhancement at least up to 68.5 min p.i.

Nuclear magnetic resonance tomography was performed on 38 patients with intracranial tumours, before and after the administration of contrast, using a 0.35 T Magnetom. The MR examinations included various plain spin-echo sequences (SE 400/35, 800/35, 1600/35, 1600/70, 1600/105, 1600/120) as well as examinations after the iv-administration of gadolinium-DTPA (SE 800/35). On all occasions, the abnormalities were visible without contrast. Differentiation of tumour and its surroundings was possible in 19 out of 38 cases without contrast. Delineation of expansively growing tumours (eg. meningiomas) was possible in twelve out of 14 cases, but in only seven out of 24 cases with infiltrating tumours (eg. glioblastomas). On the other hand, clear differentiation between tumour and adjacent edema and normal brain, respectively, was possible in 35 out of 38 cases after Gadolinium-DTPA.

The present study provides an introduction to the clinical diagnosis of intracranial lesions by means of magnetic resonance tomography (MRT). The demonstration of different tissue qualities (bone and bone marrow, cerebral cortex and medulla, ventricular system (CSF), blood, tumour and perifocal oedema) in the MR tomogram is explained. The principles of specific MRT contrast media and their clinical application in brain tumours are discussed in detail.

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.

23 out of 24 patients with multiple sclerosis showed multiple, distinct lesions on investigation with cerebral nuclear magnetic resonance imaging (NMR). Arguments for the specific relationship of these lesions to demyelinating foci are: 1. Morphology and pattern of distribution agree to the known pathological observations. 2. Single lesions shown by computerized tomography (CT) were similarly located to lesions shown by NMR. The morphology and distribution of the lesions in the NMR show a common pattern largely independent of the individual neurological deficits. The nuclear magnetic resonance imaging is a method of high sensitivity and specificity for the diagnosis of multiple sclerosis. It offers valuable additional information in particular for early diagnosis and in cases of diagnostic uncertainty.

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.

40 patients with a definite diagnosis and 16 patients with an initial manifestation of multiple sclerosis were investigated by cerebral nuclear magnetic resonance imaging (NMR) and compared. The initial manifestation is predominantly characterized in the NMR by significantly less periventricular involvement, especially within the region of the occipital horns, by significantly rarer appearance of confluent, periventricular lesions within the region of the pars centralis and the temporal horns of the lateral ventricles and by significantly rarer appearance of circumscribed non-periventricular lesions. Unlike those in definite multiple sclerosis, the morphology and distribution of the initial lesions do not show a stereotypical and diagnostically characteristic pattern. The importance of the cerebral NMR for the early diagnosis of multiple sclerosis lies primarily in the indication of disseminated lesions.

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 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.

We performed magnetic resonance tomography (MRT) on 22 patients with multiple sclerosis (MS) using varying scan sequences. In 21 patients MRT produced abnormal findings demonstrating multiple lesions, giving varying signals. The MRT appearances of MS have the following characteristics: circular configuration and homogeneous structure of individual lesions, multiple foci, with involvement of all parts of the brain, but with preference for the periventricular region and white matter. This constellation of MRT features is characteristic for MS, but is largely independent of the varying clinical symptoms. The appearance of the individual lesions and the distribution pattern of the foci is sufficiently characteristic to support the clinical diagnosis of MS in younger patients.

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.

In 14 patients with the diagnosis of glioblastoma (n = 7) or intracranial metastases (n = 7), magnetic resonance (MR) imaging was performed using a variety of spin-echo (SE) pulse sequences before and after intravenous injection of 0.1 mmol gadolinium-DTPA (Gd-DTPA) per kilogram of body weight. In 10 patients, tumor tissue could not be adequately differentiated from perifocal edema on unenhanced scans with any of the applied pulse sequences. In four cases of intracranial metastases, poor differentiation between tumor and perifocal edema was possible in T2-weighted (SE 1600/70 and SE 1600/105) unenhanced scans. After administration of Gd-DTPA, tumor tissue showed marked contrast enhancement, and tumor delineation was consistently possible on SE 800/35 images. Tumor tissue could be differentiated from perifocal edema on SE 800/70 scans. Gd-DTPA is likely to increase the potential of MR imaging and refine the evaluation of glioblastomas and intracerebral metastases.

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.

Heterotopic grey matter is a rare cause of seizures. While lesions appear suspicious on CT because of equidensity to cortex, MR imaging can establish the diagnosis by demonstrating same signal intensity of heterotopia and grey matter on T1- and T2-weighted as well as inversion-recovery sequences.

After in-vivo labeling of red blood cells with 99mTc, the radioactivity of different parts of the body is proportional to the regional blood volume. The pharmacologically caused changes of the local blood volume can be examined simultaneously in different regions of interest by functional whole-body scanning. By this technique the effect of nitroglycerin on the distribution of blood volume was investigated in 10 patients with coronary artery disease. After nitroglycerin administration we found a statistically significant diminution of blood volume over the heart, the great intrathoracal vessels, and the liver. Furthermore, there was a distinct increase of local blood volume in th legs and the arms.

Since ankylosing spondylitis (S.a.) tends to be milder and less progressive in women than in men, there are great difficulties in diagnosing S.a. in female patients. The role of scintiscanning for investigation of S.a. in women is discussed by few examiners only, especially there are no investigations of quantitative sacroiliac scintigraphy in large groups of female patients. Quantitative sacroiliac scintigraphy was performed in 19 female patients with S.a. and in 30 control subjects. The sacroiliac/sacrum ratio (Index ISG/sacrum) was calculated. Significantly increased uptakes were found in the patient group compared with the controls. Especially in the early periods of S.a. the activity index was highest. When history and physical examination lead to a suspicion of S.a. and there is no verification by roentgenographic studies, sacroiliac joint scintigraphy is indicated. If clinical and laboratory findings are respected in each patient, quantitative sacroiliac scintigraphy is useful for the early diagnosis of S.a. in female patients.

Comparative studies were made of 47 patients suffering from histologically and cytologically confirmed bronchial carcinoma, using CT and MRT respectively. CT examinations were performed before and after intravenous administration of contrast medium, whereas the MR examinations were conducted via EEG-triggered T1 and T2 marked SE sequences in the axial and coronary planes. Both methods were assessed in respect of tumour visualisation and documentation of tumour spread. Staging of tumour and lymph nodes yielded largely concurring results for CT and MRT. Exceptions were seen in 7 of 10 patients with malignant involvement of the pericardium and in 3 of 27 patients with lymph node metastases located mediastinally and subcarinally where only MRT showed a positive involvement of the pericardium or lymph nodes (with possible consequences for the staging of the tumour or lymph nodes). Decisive advantages of MRT compared with CT were seen in the identification of infiltration of the aortic-wall, in the differentiation of the poststenotic syndrome, in the visualisation of the thoracic wall infiltration and functional information on blood flow rate in upper venolus obstruction caused by a carcinoma.

Eleven patients with intracranial tumors were investigated with MR imaging at different dose levels of gadolinium-DTPA to determine a safe and effective dose for imaging intracranial tumors. The patients were divided into two groups. Baseline spin-echo images were obtained with a repetition time of 800 msec and an echo time of 35 msec, and a total of 0.1 mmol of gadolinium-DTPA/kg (six patients) or 0.2 mmol gadolinium-DTPA/kg (five patients) was injected according to a fractionated incremental dose regime (0.025, 0.025, and 0.05 mmol/kg and 0.05, 0.05, and 0.1 mmol/kg, respectively). Postcontrast MR was performed after each injection. In group 1 the best visualization was achieved after the third injection in four cases. In one glioblastoma and in a pituitary adenoma tumor margins were well defined at lower dose levels. In group 2, with five patients, the total dose of 0.2 mmol of gadolinium-DTPA/kg (0.05, 0.05, and 0.1) significantly improved tumor visualization after the third injection in only one patient with multiple metastases. No short-term side effects were encountered. In a range of parameters measured in both serum and whole blood, slight transient elevation of serum iron levels was the only appreciable change. As a result of our investigation we conclude that 0.1 mmol of gadolinium-DTPA/kg is a safe and suitable dose for brain-tumor imaging. In selected cases of 0.2 mmol/kg may increase the diagnostic yield.

47 patients with histologic/cytologic confirmed bronchogenic carcinoma were examined with CT and MRI. Negative and contrast enhanced CT examinations were performed, MR images were obtained with ECG gated T1- and T2-weighted SE sequences in axial and coronal planes. Both methods were evaluated with respect to tumor imaging and delineating of tumor extensions. CT and MRI were generally in agreement for primary tumor and lymph node staging. 7 out of 10 patients with malignant pericardial involvement and 3 out of 27 patients with mediastinal subcarinal lymph node metastases were identified only in MR images. MRI was superior to CT in demonstration of aortic involvement, poststenotic syndrome and extension of chest wall invasion. Additionally MRI gave functional informations about blood flow in case of superior vena cava obstruction.

Venous digital subtraction angiography was performed in 248 patients for the diagnosis of renal arterial stenosis. In 88% of the investigations the digital subtraction angiograms were of diagnostic value. Comparison of digital angiography and conventional angiography was made for 57 renal arteries (25 investigations). In 52 renal arteries we found the same results with both methods, in 5 renal arteries the digital angiography showed false positive results. The spatial resolution of digital subtraction angiography is sufficient for the correct diagnosis of significant renal arterial stenosis. With regard to the lower invasion of digital subtraction angiography compared to conventional angiography the first method should be used for clarification of renal arterial hypertension.

The value of T1 and T2-weighted spin echo sequences for making a specific diagnosis of focal renal disease was evaluated in 105 MR examinations. Typically, hypernephromas are characterised by a reduced or only slightly increased T1 or T2 signal, whereas previous bleeding and long-standing abscesses result in increased signal strength, particularly with T2-weighted sequences. In this way, hypernephromas can be characterised; this is not always possible with CT. Angiomyolipomas also have characteristic signals. MR has no advantages in the diagnosis of recent bleeding, acute focal inflammatory lesions, metastases, carcinoma of the renal pelvis or atypical cysts.

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.

52 patients with cerebral tumours were examined by both CT and MR. Contrast media containing iodine were used in CT, whereas in MR a paramagnetic contrast medium (gadolinium-DTPA) was applied by IV injection. A comparison of CT and MR findings showed that with both methods it was often not possible to achieve sufficient visualization and delineation of tumour tissue without employing a contrast medium. After application of the contrast medium, the shape and size contrast enhancement in the tumour tissue in both CT and MR was practically identical. This enables direct visualization of the tumour, superior delineation from the adjacent tissue, and differentiation between oedema and tumour, resulting in effective treatment planning which would otherwise not be possible.

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.

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%.

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.

Gd-DTPA-dimeglumine is a new contrast agent for magnetic resonance imaging. Its safety and efficacy in man were evaluated in 20 volunteers and 60 patients. For determination of tolerance of Gd-DTPA, blood and urine samples were taken and blood pressure, pulse rate, and ECG were recorded before and after injection. The results of these analyses showed no clinically relevant changes. In MR imaging of intracranial lesions Gd-DTPA serves as an indicator of function or disfunction of the blood-brain-barrier, because its pharmacokinetic behavior is very similar to that of urographic iodinated contrast media used now for X-ray CT. And so by using Gd-DTPA it is possible to differentiate between neoplastic tissue and perifocal edema, to determine the extension of tumor infiltration, and to detect tumor recurrence.

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.

Gated magnetic resonance tomography (MRT) was conducted in 40 patients (13 normal volunteers, 9 hypertensives and 18 patients with hypertrophic cardiomyopathy) using a 0.35 Tesla superconducting magnet. Multisectional spin echo imaging (35/400 msec) was obtained in coronal, transversal and sagittal planes. Myocardial wall thickness was measured in different segments and the three groups were compared to each other. 15/18 patients with hypertrophic cardiomyopathy (HCM) had asymmetrical regional thickening involving the septum and the anterior wall, in 8/15 the lateral wall was also hypertrophic. The distribution pattern in 3/15 patients with HCM was symmetric. Involvement of the right ventricle was found in 14/18 patients with HCM. There were significant differences (p less than 0.001) in wall thickness for the septal segment in all three groups and for the ratio septal to posterior wall between the HCM and the hypertensives and the normal volunteers. We conclude that MRT can differentiate HCM from hypertensives and normals, and is superior to echocardiographic imaging in the evaluation of the distribution of left ventricular hypertrophy in hypertrophic cardiomyopathy.

The effectiveness of ultrasound, computed tomography, hepatobiliary scintigraphy and nuclear magnetic resonance in diseases of the biliary tract is described. Ultrasound should be the first examination in clinical suspicion of cholelithiasis and has a higher accuracy than oral cholecystography. Computed tomography is very expensive and should be carried out in suspected gallbladder carcinoma, cholecystitis with abscess formation, tumour in the porta hepatis and pancreatic head and in sonographically unclear cases. Nuclear magnetic resonance can determine the ability of the gallbladder to concentrate bile. Ultrasound can distinguish with high accuracy between obstructive and inflammatory jaundice. In clinical suspicion of bile duct lesions an infusion cholangiogram must be carried out, if bilirubin is lower than 5 mg%; if bilirubin is higher, an ERC or PTC should be performed. If in biliary obstruction a suspicion of tumour in porta hepatis or head of the pancreas is present, computed tomography should be effected.

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.

In 50 patients with temporal-lobe epilepsy, CT and MR findings were compared. Axial CT scans were obtained before and after administration of contrast material. Coronal MR imaging was carried out with two spin-echo (SE) sequences with a repetition time of 1600 msec and echo times of 35 or 70 msec (SE 1600/35, SE 1600/70). A focal lesion was detected by CT in 12 cases and by MR in 16 cases. If discrete attenuation or signal abnormalities are also taken into account, CT provided a positive finding in 13 cases and MR imaging in 20 cases. With the exception of a small calcification, all the lesions revealed on the CT scans were also detected on the MR images. Among the examinations assessable for temporal-lobe asymmetry, signs of a unilateral reduction in temporal-lobe size were seen on two of 35 CT scans and on 15 of 38 MR images. In three patients who had temporal-lobe resection, a subsequent comparison was made between CT, MR imaging, and pathology. Histologically proven glial reactions that could not be detected on CT were demonstrated as high-signal-intensity lesions on the SE 1600/70 image. We conclude that MR scanning, with its higher sensitivity, superior image quality, and ability of multiplanar imaging, should be the imaging technique of choice in the diagnosis of temporal-lobe epilepsy.

Twenty-five patients with clinical and CT findings indicating supratentorial cerebral infarct were prospectively studied with MR. MR examinations were performed between the 3rd and 150th day after stroke. T2-weighted axial images were compared with T1-weighted sequences after i.v. administration of Gd-DTPA. T2-weighted images demonstrated parenchymal lesions in all 25 patients. Postcontrast T1-weighted images, however, displayed pathologic contrast enhancement in only 19 areas of infarction. In 5 of the 25 patients, the use of Gd-DTPA provided additional diagnostic information by demonstrating gyral contrast enhancement as a pattern typical for ischemia. In 2 of the 25 patients, pathologic contrast enhancement was observed in an area that was isointense to the surrounding brain tissue on the T2-weighted images. In one patient, Gd-DTPA improved differentiation between areas of subacute and chronic infarction. At present, in the patient with suspected cerebral infarction, MR imaging after i.v. administration of Gd-DTPA appears recommended when clinical findings and CT are equivocal.

Cortical somatosensory evoked potentials following median and tibial nerve stimulation were compared with the findings in nuclear magnetic resonance imaging in 23 patients with multiple sclerosis, 11 of whom presented with their first disease manifestation. Pathological SEP's were found in 55 percent of patients presenting with first manifestation and in 83 percent of those with a longer duration of illness. Except for one patient with spinal cord involvement only, in whom no cerebral lesions were seen, all patients showed periventricular lesions in NMR. Between 1 and 16 (4.7 +/- 3.5) non-periventricular isolated lesions were found per patient. Cortical SEP's are affected differently by lesions within the thalamocortical system: Plaques within the internal capsule may result in SEP-changes as seen in other causes of damage to this region. However, lesions in this strategic area may also remain clinically and electrophysiologically silent. Nevertheless, the size of the lesion seen in NMR is not relevant, as observed in one case of an extensive plaque within the centrum semiovale. Correlations between the lesions near the parietal cortex or within the parietal white matter and SEP-component alterations of intermediate latency (N55, N75) remained insignificant.

Magnetic resonance imaging of normal and pathological kidneys and the method of examination are demonstrated. The anatomy of the kidneys is excellently displayed by means of magnetic resonance imaging which can also distinguish between the renal cortex and renal medulla. Renal tumors and cysts can easily be recognized and differentiated by means of magnetic resonance imaging and the extension of the tumor (staging) can be defined. The principles of magnetic resonance imaging contrast media are described as well as the primary results obtained from administration of contrast media in volunteers. At the present time, ultrasound and computed tomography are the first imaging methods in recognition and differentiation of space occupying lesions of the kidneys. Magnetic resonance imaging should only be utilised in complicated cases, e.g. haemorrhagic cysts or when computed tomographic results show a suspected tumor invasion of the renal vein or tumor thrombus in the vena cava.