A magnetic resonance study of early schizophrenia

Patients with untreated first schizophrenic episodes and others who had made varying degrees of recovery from such episodes were blindly compared with normal volunteers in terms of the periventricular appearances on spin echo magnetic resonance scans. Significant differences were not found.

MRI in acoustic neuroma: a review of 35 patients

This retrospective study is aimed to assess the diagnostic efficacy of MRI in relation to contrast enhanced CT and air-CT-cisternography. MRI examinations were performed in 35 patients with suspected neurosensorial damage and suggestive of acoustic neuroma: 27 presented on MRI with unilateral tumors, 3 patients had a bilateral tumor and 5 patients were negative on all imaging modalities. The total number of acoustic neuromas detected was therefore 33. To date microscopic analysis has been performed on 12 tumors and histological data based on type Antoni A and Antoni B classification is available. Contrast enhanced CT detected 19 tumors, yielding an overall sensitivity rate of 58%. Air-CT cisternography identified an additional 5 tumors with a sensitivity rate of 100%. MRI identified 33 acoustic neuromas in 30 patients and was negative in 5 patients (sensitivity and accuracy 100%). Considering sensitivity in relation to location, MRI was much better than contrast enhanced CT for internal auditory canal (IAC) tumors (100% versus 36%) and better for cerebello-pontine angle tumors (CPA) tumors (100% versus 68%). The evolution of MRI technique, the various pulse sequences used and their actual selection is discussed. Seven patients received a paramagnetic contrast agent (Gadolinium-DTPA) with the additional benefit of a better demonstration of the tumor. The results suggest that MRI is the best non invasive technique for demonstrating acoustic neuromas.

MR imaging in progressive multifocal leukoencephalopathy

The MR imaging appearance of progressive multifocal leukoencephalopathy is described in four cases that were confirmed by brain biopsy. Characteristic aspects are long T1 and long T2 lesions limited to white matter. At first the lesions are round or oval, then confluent and large. There is no mass effect. The involvement is most often asymmetric and distant from the periventricular region. The differential diagnosis includes other diseases affecting white matter: demyelination, infarction, infection, and tumors.

MRI of the abdomen

Clinical MRI of the body has not so far produced results consistently comparable with X-ray CT or high-resolution real-time ultrasound. Present development in MRI technology (new sequences, respiratory gating) and the application of paramagnetic contrast agents are however promising features. MRI might play a useful rôle also in abdominal examination.

MR imaging of the liver using short TI inversion recovery sequences

Use of the short inversion time inversion recovery (STIR) sequence in magnetic resonance (MR) imaging of the liver is illustrated in 20 patients. The sequence provides high contrast images of the liver with relatively little degradation due to motion. Lesions appeared more extensive than with X-ray CT in 14 cases and equal in six. Additional areas of presumed atrophy, fatty infiltration, edema, or vascular insufficiency were only seen with MR. The STIR sequence may be valuable in screening of the liver for metastatic disease.

NMR imaging of congenital intracranial germinal layer neoplasms

NMR images in five patients with surgically proved, congenital germinal layer intracranial neoplasms (two dermoid and three epidermoid tumors) were reviewed. The dermoids were typically midline (suprasellar or parapineal) masses with sharply-defined margins. Relaxation times were variable, but if fat was present, T1 was decreased, and T2 was increased. The epidermoids were off the midline (cerebellopontine angle, temporal lobe, frontal lobe) masses with generally long T1 and T2 relaxation times. Obstructive hydrocephaly was noted in one patient, and tumor to ventricular communication was demonstrated in another.

Agenesis of the corpus callosum: magnetic resonance imaging

Three patients who had complete agenesis and two patients who had partial agenesis of the corpus callosum (ACC) underwent magnetic resonance (MR) imaging. In addition to excellent visualization of the indirect signs of ACC, direct vivid display (short T1) of the corpus callosum on sagittal images allowed better evaluation of subtle abnormalities than has been possible with other modalities. Associated abnormalities were also well-displayed. MR is the initial procedure of choice in evaluation of the corpus callosum.

Magnetic resonance imaging in infections of the central nervous system

The magnetic resonance (MR) images in 24 patients with infections of the central nervous system (CNS) were reviewed, and the use of a paramagnetic contrast agent (Gd-DTPA) in two cases is reported. The clinical diagnoses in the patients, aged neonate to 71 years old, comprised meningitis, meningitis and subdural empyema, meningoencephalitis, encephalitis, and single or multiple cerebral abscesses. A new sign of CNS infection, the pial-ependymal line, is described. Other consequences of infection, such as atrophy, delayed myelination, periventricular cerebrospinal fluid extravasation, changes in T1 and T2, and mass effect, are reported and discussed. MR imaging may have a significant application in the study of CNS infections because of the importance of early diagnosis in instituting effective treatment.

The short TI inversion recovery sequence--an approach to MR imaging of the abdomen

Initial clinical experience with magnetic resonance imaging (MRI) of the abdomen using short TI inversion-recovery (STIR) pulse sequences is described and compared with X-ray CT in a variety of abdominal disease. The extent of abnormality shown with MRI was greater than that with CT in 21 of 30 cases and equal in 9 cases. Lesion contrast was greater with MRI in 15 cases, equal in 14 and less in 1. The level of artefact was equal in 27 cases and greater with MRI in 3 cases. The STIR pulse sequence has significant advantages in producing high soft-tissue contrast, controlling respiratory artefact, avoiding confusion with intra-abdominal fat and identifying bowel loops.

Contrast-enhanced MR imaging of malignant brain tumors

Magnetic resonance (MR) imaging was performed before and serially after intravenous injection of 1 mmol/kg gadolinium-DTPA (Schering) in 17 patients with clinical and histologic diagnosis of malignant cerebral tumors. There was a decrease of 1% in T1 and 10% in T2 in normal white matter and a decrease of 8% in T1 and 14% in T2 in normal gray matter. Contrast enhancement was observed in 16 of the 17 tumors. In the region of maximal enhancement a mean decrease of 16% in T1 was observed in low-grade gliomas, a mean decrease in T1 of 29% was seen in high-malignancy gliomas, and a mean decrease in T1 of 33% was observed in metastases. The decreases in T1 persisted for at least 50 min. In one case the central cystic region of the tumor displayed a decrease in T1 and T2. Measurements of signal intensity displayed maximal contrast enhancement with an IR 1500/500/44 sequence, much less with SE 1500/44, and least with SE 1500/80. Edema was observed on precontrast images in 14 cases, but satisfactory definition of the tumor-edema margin was only possible in four cases. After contrast enhancement this margin was defined in 10 cases. In four of the 17 cases areas of apparent "edema" seen before administration of Gd-DTPA displayed significant contrast enhancement and probably represented tumor infiltration. Comparison with CT showed a greater degree of contrast enhancement on MR images in eight cases, an equal degree in eight cases, and greater enhancement on CT in one case.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance imaging of the kidneys

A study of the magnetic resonance imaging (MRI) appearances of the kidneys in six normal volunteers and 52 patients is reported. Corticomedullary differentiation was seen with the inversion-recovery (IR 1400/400) sequence in the normal volunteers and in patients with functioning transplanted kidneys and acute tubular necrosis. Partial or total loss of corticomedullary differentiation was seen in glomerulonephritis, acute and chronic renal failure, renal artery stenosis, and transplant rejection. The T1 of the kidneys was increased in glomerulonephritis with nephrotic syndrome, but the T1 was within the normal range for renal medulla in glomerulonephritis without nephrotic syndrome, renal artery stenosis, and chronic renal failure. A large staghorn calculus was demonstrated with MRI, but small calculi were not seen. Fluid within the hydronephrosis, simple renal cysts, and polycystic kidneys displayed very low signal intensity and long T1 values. Evidence of recent hemorrhage into cysts was seen in polycystic kidneys. Tumors displayed varied appearances. Hypernephromas were shown to be hypo- or hyperintense with the renal medulla on the IR 1400/400 sequence. After intravenous injection of gadolinium-DTPA, there was marked decrease in the tumor T1.

Gadolinium-DTPA as a contrast agent in MRI: initial clinical experience in 20 patients

Magnetic resonance imaging (MRI) was performed in 20 patients before and after intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) in a dose of 0.1 mmol/kg. Twelve of the patients had clinical and histologic diagnoses of cerebral tumor, six had hepatic tumors, one had hepatic cysts, and one had transitional cell carcinoma of the bladder. Contrast enhancement was seen with all tumors, but not with the hepatic cysts. The degree of enhancement was greater than that seen with computed tomography (CT) in 13 cases, equal to it in six, and less in one. Contrast enhancement was detectable as long as 18 hr after injection of Gd-DTPA in one case of cerebral tumor. The margin between cerebral tumor and peritumoral edema could be delineated with contrast-enhanced MRI to the degree possible with contrast-enhanced CT. In the liver isointense enhancement was seen with saturation-recovery (SR), inversion-recovery (IR), and spin-echo (SE) sequences although not with all three sequences simultaneously. In general IR sequences were most sensitive for display of the contrast agent, but the enhancement often decreased the difference between abnormal and normal tissue. No short-term side effects were encountered and no significant change was seen in urea, creatinine, electrolytes, liver function tests, blood coagulation, or urine testing after injection of Gd-DTPA. Although much more work will be required to evaluate this contrast agent, these initial experiences are very promising.

NMR imaging of the liver in two cases of iron overload

Two cases of iron overload in the liver are presented--one of hemochromatosis with associated hepatoma and one of hemosiderosis with probable androgen dependent multicentric hepatic adenomas. Nuclear magnetic resonance scans displayed the tumours as well as low liver parenchymal signal intensity on the saturation-recovery, inversion-recovery, and spin-echo pulse sequences probably as a result of decreased tissue T1 and T2.

Effect of oxygen tension on NMR spin-lattice relaxation rate of blood in vivo

Spin-lattice relaxation rate (1/T1) was measured in the left (LV) and right (RV) ventricular cavities in four conscious normal humans and four anesthetized greyhound dogs breathing spontaneously. Inspired oxygen concentration (FIO2) was varied in five steps from 21 to 100%. In dogs, blood was sampled from indwelling catheters in the pulmonary artery and aorta for measurement of PO2. Saturation-recovery and inversion-recovery tomographic images of the ventricular cavities were obtained supine during quiet breathing using a whole-body NMR scanner operating at a static magnetic field strength of 0.15 Tesla. From FIO2 21 to 100%, 1/T1 of LV increased by 11.6% in humans and 9.6% in dogs. In dogs, 1/T1 increased by 2.8% per 100 mm Hg increase in aortic PO2 (r greater than 0.87). There was no correlation in dogs between 1/T1 in RV and pulmonary artery PO2. The LV/RV 1/T1 ratio in dogs increased by 4% per 100 mm Hg increase in the LV-RV PO2 difference, and by 8% in humans as FIO2 increased from 21 to 100%. A rise in dissolved oxygen concentration increases NMR spin-lattice relaxation rates of blood in vivo to a small but significant extent.

The NMR diagnosis of cerebral tumors

The results of NMR examinations in 52 patients with histological or clinical diagnoses of cerebral tumor are reviewed. An increase in relaxation time was recognized in all tumors but problems were experienced in distinguishing the margin of tumors from surrounding edema. Mass effects were well demonstrated as a result of the high level of gray-white matter contrast available with inversion-recovery sequences and the use of coronal and sagittal imaging planes. In general repeated FID sequences were less sensitive in detecting tumors than inversion-recovery or spin-echo sequences. Periventricular edema was well demonstrated with spin-echo sequences and was of importance in recognizing acute or subacute hydrocephalus. Radiation therapy was associated with increased relaxation times particularly within white matter. Problems in the recognition of tumor recurrence following treatment are outlined. The opportunities and challenges that NMR imaging is now providing for physicists and radiologists are discussed.

NMR imaging of central nervous system diseases before and after radiotherapy

Two brain tumors, a foramen magnum tumor and an arterio-venous malformation (AVM) were treated with radiation but without chemotherapy or surgical removal. These cases were monitored by NMR imaging for a period of 16 months after radiotherapy to detect the response of the tumors and brain tissue to radiation. The T1 and T2 of the tumors behaved independently. T1 decreased after radiation related to clinical improvement. T2 did not change to the same degree as T1. An increased T2 area around the tumors and along the lateral ventricle developed about six months in one case and 16 months in the other case after radiotherapy, without associated clinical change in either case.

Magnetic resonance imaging of intracranial tumors in children and adolescents

Magnetic resonance (MR) scans were reviewed of 25 children and adolescents from the age of 9 months to 18 years referred with a suspected or proven diagnosis of intracranial tumor. Twenty-one of these children had MR scans positive for tumor. Histology was available in 14. The other seven patients were managed clinically as cases of cerebral tumor, although histologic confirmation was lacking. Seventeen tumors displayed an increase in both T1 and T2. One dermoid tumor and part of another displayed a very short T1 (less than that of white matter). Two hamartomas had T1s similar to that of gray matter and a small increase in T2. Four of the children did not show MR or computed tomographic (CT) evidence of intracranial tumors. Follow-up of these cases for 1-23 months after the MR and CT studies revealed no subsequent clinical evidence of tumor. MR scans showed more extensive abnormality than did third-generation CT scans in eight of 10 cases and more extensive abnormality than EMI CT 1010 scans in 10 of 11 cases. Mass effects were better demonstrated in 14 of the 16 patients in whom they were seen. CT demonstrated calcification better than did MR in all four cases in which it was identified. The tumor-edema interface was shown better on CT in each of the three cases with contrast enhancement on CT. MR is a sensitive method of evaluating intracranial tumors in children and adolescents.

Clinical NMR imaging of the brain and cord

After a short explanation of the NMR imaging technique the normal appearances of the brain are described. Subsequently the paper deals with the NMR images of vascular disease, white matter disease, tumors of the brain and paediatric neurological disease. The conclusion is that NMR has advantages over CT of the brain in certain fields, but that exploration of its full potential has hardly yet begun.

Nuclear magnetic resonance in gastroenterology

Insufficient clinical results are yet available to determine the likely clinical role of NMR in gastroenterology. In some instances unique information is available from NMR imaging but ultrasound and CT also provide valuable information in a wide variety of diseases. Many of the organs and tissues within the abdomen are accessible to biopsy, and a variety of other biochemical tests have specific roles in assessing disease within the abdomen and pelvis. Virtually all NMR machines in current use are research prototypes rather than clinical instruments designed for routine use. Major questions about design are unresolved, such as whether resistive, permanent or cryogenic magnets should be used. There is also little agreement about the optimum field for imaging. The value of spectroscopy in research and clinical use is another unknown factor and it is probable that this will provide useful information in research applications at least. At the present time it is important to note the developments occurring in NMR imaging and the potential of this technique, although it is not yet possible to predict what value it may have in clinical practice. There are many current research developments, such as flow imaging and the imaging of 23Na which have been demonstrated in the laboratory but have not yet been applied in clinical practice. It is also possible that respiratory gating may result in considerable improvement in image quality. The use of paramagnetic contrast agents is another developing field. These agents, including molecular O2, iron, manganese and gadolinium, have the effect of decreasing T1 and T2. Gadolinium chelates have been used in animals and will soon be evaluated in humans. Not only do these materials act as contrast agents in their own right but they may be linked as markers to metabolites, antibodies and other compounds. Direct measurements of T1 and T2 may prove to be of value although initial results indicate that they are rather non-specific. Whether NMR will remain largely of research interest or will play a useful role in clinical practice remains to be seen but will certainly be the subject of intense investigation over the next few years.