Nuclear Magnetic Resonance Scans Research Articles

Proportional localization system for anatomical interpretation of cerebral computed tomograms.

The existence of individual variations in size and shape of the human brain constitutes a problem for the anatomical interpretation of brain reconstructed images obtained from scanning devices; it is, for example, responsible for most of the inaccuracies in reading CT scans. One way to account for these variations is to use a proportional localization system. In the 1960s a group of neurosurgeons developed such a system based on two pivotal intracerebral structures, the anterior and the posterior commissures; they published an atlas consisting of horizontal, coronal, and sagittal brain sections interpreted in the proportional system. The atlas also included standard proportional brain schemes based on anatomical and radiological studies on large numbers of individuals. In this article we report a target localization experiment that we carried out to determine if this atlas could be used as a reference for a more accurate interpretation of CT and, eventually, of positron emission tomography (PET) and nuclear magnetic resonance (NMR) scans. Ten radiopaque small targets were inserted through the skull in the cortex of three cadavers; head CT was performed, and the atlas was used for predicting the cortical location of the targets seen on the CT images: The predictions were confirmed. These results strongly support the use of the proportional atlas for the interpretation of CT as well as of PET and NMR scans.

Unilateral hydrocephalus combined with occlusion of the ipsilateral internal carotid artery

The authors encountered a rare case of a patient who developed a mild hemiparesis on the right side at age 8 months with marked enlargement of the left lateral ventricle and occlusion of the ipsilateral internal carotid artery. In computed tomography scans and nuclear magnetic resonance scans 8 years after an operation to install a ventricular shunt, there was marked enlargement of the left lateral ventricle and almost no left basal ganglion. In this case, the differentiation between hydranencephaly and severe hydrocephalus presented a problem because no biopsy had been performed. Diagnosis was difficult, but it appeared that conclusion of the ipsilateral internal carotid artery played a major role.

Magnetic Resonance Imaging:Overview of the Technology and Medical Applications

The physical phenomenon of nuclear magnetic resonance (NMR) was first characterized almost forty years ago in 1946 by the simultaneous but independent experimental successes of American scientists Felix Bloch and Edward Purcell. Their discoveries prompted development of conventional NMR spectroscopy. a technique used to describe the molecular composition and behavior of chemical compounds. Twenty-five years later, in 1971, Damadian used NMR to demonstrate differences in the behavior of water in malignant and benign tissues, and he suggested that NMR possessed “many of the desirable features of an external probe for the detection of internal cancer” (7). In the same year, Lauterbur produced the first two-dimensional NMR image, a cross-sectional portrait of two tubes of water (25). The potential utility of this technique to medical imaging was obvious, and soon afterwards multiple researchers began development of clinical NMR imaging systems. The first human whole-body NMR scan was accomplished by 1977. Improvements in the scanning process and image quality continue with, as yet, no limits in sight. In this clinical context, NMR techniques have experienced a name change to the current prevailing appellation, magnetic resonance imaging (MRI).

A case of 'essential' hypernatraemia due to resetting of the osmostat.

We describe a 24-year-old short, obese girl who has bizarre episodic neurological abnormalities related to hyperosmolality due to hypernatraemia. Investigation of osmoregulation by water loading and infusion of hypertonic saline revealed (i) hypodipsia with thirst onset raised to plasma osmolality of 332 mmol/kg and (ii) elevation of the threshold for vasopressin release (plasma osmolality 320 mmol/kg) but normal slope of the plasma vasopressin-plasma osmolality curve. Baroregulated vasopressin release was also grossly subnormal. Other hypothalamo-pituitary investigations showed deficiencies of releasing hormones for gonadotrophins and growth hormone, but prolactin response to combined hypoglycaemia and TRH was blunted She demonstrated other anomalies including hyperlipoproteinaemia and defective lymph drainage of the legs. Skull X-rays, together with computerized tomography and nuclear magnetic resonance scans of the hypothalamo-pituitary region and the rest of the brain were normal. We believe that this is the first case of essential hypernatraemia documented with direct evidence of resetting of the osmostat.

Nuclear magnetic resonance scans: Imaging assisted by the computer

Nuclear magnetic resonance scans: Imaging assisted by the computer

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Nuclear magnetic resonance scans (NMR-CT) were performed on patients with posterior fossa disorders such as acoustic neurinoma, cerebellar tumour (gangliocytoma), epidermoid tumour and spinocerebellar degeneration, and compared with X-ray computed tomography (CT) scans.The advantages of NMR-CT include lack of bone artifact, variety of image planes, transverse, sagital and coronal imaging, and high ability to differentiate tissues. The disadvantages include prolonged data accumulation time, lack of bone detail and calcification, limited spatial resolution and suitability of patients.

Nuclear magnetic resonance in schizophrenia: A preliminary study

Nuclear magnetic resonance (NMR) scans were performed in nine patients with schizophrenia and five control subjects. NMR scans allowed multiple-plane views of the brains of schizophrenic patients and demonstrated much greater detail of morphological structure than computed tomographic (CT) scans. This small sample of subjects,however,showed no significant differences in several quantitative measurements betweeen schizophrenic patients and control subjects. Problems in the interpretation of image intensity measures of NMR scans are discussed.

Nuclear magnetic resonance imaging of the liver: Initial experience

Nuclear magnetic resonance (NMR) scans of the liver were obtained in 12 normal volunteers and 32 patients using a whole-body machine developed by Thorn-EMI Ltd., and the results were compared with x-ray computed tomography (CT). Two types of NMR scan, saturation-recovery and inversion-recovery, were performed in order to obtain values for the spin-lattice relaxation time, T1. Although the saturation-recovery scans show little soft-tissue detail, the inversion-recovery scans demonstrated the interlobar fissure, hepatic veins, portal veins, bile ducts, and gallbladder. In comparison with CT (Siemens Somatom 2), both types of NMR scan showed some blurring due to respiratory movement but much less linear artifact across the liver from the air-fluid interface in the stomach. Focal disease within the liver was demonstrated by both CT and NMR, although an area of focal atrophy and another of hepatic infarction were only recognized with NMR. In diffuse disease the pattern varied. In steatosis CT was virtually diagnostic, while NMR showed no specific features. In hemochromatosis, hepatitis, eight cases of cirrhosis, and one of Wilson disease, both techniques showed abnormalities of varying specificity. In two cases of cirrhosis and one of primary biliary cirrhosis, only the NMR scan was abnormal. Nuclear magnetic resonance images are now sufficiently anatomically detailed to permit serious comparisons with technically advanced computed tomography. The information revealed is fundamentally different and can be expected to have some diagnostic utility.

Recognition of lumbar disk herniation with NMR

Fifteen nuclear magnetic resonance (NMR) studies of 14 patients with herniated lumbar intervertebral disks were performed on the UCSF NMR imager. Computed tomographic (CT) scans done on a GE CT/T 8800 or comparable scanner were available at the time of NMR scan interpretation. Of the 16 posterior disk ruptures seen at CT, 12 were recognized on NMR. Diminished nucleus pulposus signal intensity was present in all ruptured disks. In one patient, NMR scans before and after chymopapain injection showed retraction of the protruding part of the disk and loss of signal intensity after chemonucleolysis. Postoperative fibrosis demonstrated by CT in one patient and at surgery in another showed intermediate to high signal intensity on NMR, easily distinguishing it from nearby thecal sac and disk. While CT remains the method of choice for evaluation of the patient with suspected lumbar disk rupture, the results of this study suggest that NMR may play a role in evaluating this common clinical problem.

Nuclear magnetic resonance imaging of the mediastinum and hili: Early impressions of its efficacy

Nuclear magnetic resonance (NMR) scans of the mediastinum and/or hili were obtained in 22 of 25 patients selected on the basis of an abnormal CT scan. All patients had proven disease; 19 malignant and four benign processes were studied successfully. The high contrast resolution of NMR in the mediastinum allowed clear definition of disease in all cases. In six, NMR showed a greater extent of disease than CT. The ability of NMR to perform sagittal and coronal images also aided in disease analysis. In this preliminary study, NMR proved to be as useful as CT, or more so, in the evaluation of malignant disease of the hili and mediastinum.

Recognition of lumbar disk herniation with NMR.

Fifteen nuclear magnetic resonance (NMR) studies of 14 patients with herniated lumbar intervertebral disks were performed on the UCSF NMR imager. Computed tomographic (CT) scans done on a GE CT/T 8800 or comparable scanner were available at the time of NMR scan interpretation. Of the 16 posterior disk ruptures seen at CT, 12 were recognized on NMR. Diminished nucleus pulposus signal intensity was present in all ruptured disks. In one patient, NMR scans before and after chymopapain injection showed retraction of the protruding part of the disk and loss of signal intensity after chemonucleolysis. Postoperative fibrosis demonstrated by CT in one patient and at surgery in another showed intermediate to high signal intensity on NMR, easily distinguishing it from nearby thecal sac and disk. While CT remains the method of choice for evaluation of the patient with suspected lumbar disk rupture, the results of this study suggest that NMR may play a role in evaluating this common clinical problem.

Nuclear magnetic resonance imaging of the mediastinum and hili: early impressions of its efficacy.

Nuclear magnetic resonance (NMR) scans of the mediastinum and/or hili were obtained in 22 of 25 patients selected on the basis of an abnormal CT scan. All patients had proven disease; 19 malignant and four benign processes were studied successfully. The high contrast resolution of NMR in the mediastinum allowed clear definition of disease in all cases. In six, NMR showed a greater extent of disease than CT. The ability of NMR to perform sagittal and coronal images also aided in disease analysis. In this preliminary study, NMR proved to be as useful as CT, or more so, in the evaluation of malignant disease of the hili and mediastinum.

Nuclear magnetic resonance evaluation of stroke. A preliminary report.

Nine patients who had acute and subacute stroke were examined by nuclear magnetic resonance (NMR) using a 6-MHz Bruker Instruments proton scanner. A modified Carr-Purcell-Meiboom-Gill pulse sequence was used for signal detection. The resultant string of spin-echoes was Fourier transformed into projections that were subsequently back-projected to a series of spin-echo images. From these images, spin density and T2 were calculated for each pixel. The NMR scans revealed stroke in each of the patients, while CT demonstrated only eight of the lesions. T2 was prolonged in all of the ischemic regions and is the most sensitive NMR parameter in detecting stroke. These preliminary results suggest that NMR scanning of patients who have acute stroke may be clinically useful, and that the T2 component of the NMR signal is most important.

The application of nuclear magnetic resonance data to radiation therapy

The appropriate therapeutic modality for a patient with a malignancy depends on knowledge of the extent of the disease. If the disease is localized and suited for a course of conventional radiotherapy, delineation of the borders of the gross tumor is necessary for treatment planning. The proton nuclear magnetic resonance scan may be useful in precisely delineating the extent of the tumor due to large differences in the spin-lattice relaxation times between normal and malignant tissues. Proton NMR scanning can also be used to provide information on the relative hydrogen concentration of various tissues in situ. Knowledge of the hydrogen concentration is required to calculate the dose to an organ irradiated with a fast neutron beam.

NUCLEAR MAGNETIC RESONANCE IMAGING OF THE BRAIN IN MULTIPLE SCLEROSIS

Ten patients with multiple sclerosis (MS) were scanned by means of cranial X-ray computed tomography (CT) with and without intravenous contrast enhancement, and by nuclear magnetic resonance (NMR) using an inversion-recovery sequence. Altogether 19 lesions varying in size between about 7 mm X 5 mm and 13 mm X 8 mm were demonstrated by CT. They were all situated in the periventricular region. Two patients also showed moderate ventricular enlargement. In addition to these abnormalities 112 further lesions were demonstrated on the NMR scans. These lesions varied in size from 4 mm X 3 mm to 12 mm X 7 mm and were particularly well seen in the periventricular region and brainstem. Care is required in the assessment of NMR scans to exclude artefacts, background noise, and mottle as well as normally situated grey matter and partial volume effects from cerebral sulci. NMR nevertheless demonstrates abnormalities in MS on a scale not previously seen except at necropsy.

Clinical NMR imaging of the brain: 140 cases

Cranial nuclear magnetic resonance (NMR) scans were performed on 13 healthy volunteers and 140 patients with a broad spectrum of neurologic disease and compared with x-ray computed tomography (CT) scans. The NMR scans included a variety of sequences reflecting proton density, blood flow, T1, and T2 as well as transverse, sagittal, and coronal images. White matter, gray matter, and cerebrospinal fluid were clearly distinguished in the normal brain with inversion-recovery (IR) sequences, and normal progressive myelination was demonstrated in infants and children. Acute hemorrhages displayed short T1 values, but other pathologic processes such as infarction, infection, demyelination, edema, and malignancy were associated with long T1 values. Cysts had very long T1 values (about that of cerebrospinal fluid). Spinecho (SE) sequences showed increased values of T2 in a variety of conditions and highlighted lesions against the relatively featureless background of the remaining brain. With inversion-recovery scans, different stages of infarction were recognized in the hemispheres. NMR was more useful than CT in demonstrating brainstem infarction. The white matter lesions in demyelinating diseases were well demonstrated with NMR scans. Many more lesions were observed in multiple sclerosis with NMR than with CT. Benign tumors were well seen and usually had shorter T1 values than malignant tumors. Mass effects from tumors were generally better demonstrated with NMR than with CT, including more subtle mass effects such as displacement of the external capsule. Abnormalities were seen in diseases of the basal ganglia, including marked atrophy of the head of the caudate nucleus in Huntington chorea. Advantages of NMR imaging include the high level of gray–white matter contrast, lack of bone artifact, variety of possible sequences, transverse, sagittal, and coronal imaging, sensitivity to pathologic change, and lack of known hazard. Disadvantages include lack of bone detail, limited spatial resolution, lack of contrast agent s, and cost. Promising directions for future clinical research include developmental neurology, tissue characterization with T1 and T2, assessment of blood flow, and the development of contrast agents. Much more detailed evaluation will be required, but NMR seems to be a potentially important addition to existing techniques of neurologic diagnosis.

NMR imaging of the brain using spin-echo sequences

Eight normal volunteers and 32 patients with a variety of neurological disease were studied with a nuclear magnetic resonance (NMR) scanner using repeated free induction decay (RFID), inversion-recovery (IR) and spin-echo (SE) sequences. The results were compared with X-ray computed tomography (CT). RFID sequences which produce images that reflect changes in proton density displayed very little grey-white matter contrast and relatively small changes in disease. IR sequences which produce images that are dependent on T1 showed a high level of grey-white matter contrast and demonstrated changes in a variety of pathological processes. Although SE scans, which have a strong T2 dependence, had shown no abnormality in previous studies of patients with neurological disease, sequences of this type with longer values of tau displayed abnormalities in cerebral infarction, haemorrhage, herpes encephalitis, multiple sclerosis, cerebral oedema, hydrocephalus, tumours and Wilson's disease. All of these conditions were associated with an increase in T2. Abnormalities were demonstrated in cases of multiple sclerosis and brainstem infarction with NMR scans where no abnormality was seen with CT. More extensive changes were seen with NMR in cases of hemisphere infarction, systemic lupus erythematosis, herpes encephalitis, hydrocephalus (periventricular oedema) and Sturge-Weber disease. The margin between malignant tumour and surrounding oedema was better defined with contrast enhanced CT in four of eight malignant tumours, equally well defined in one, and better defined with NMR in three cases. NMR spin-echo sequences provide a sensitive technique for detecting abnormalities in a variety of neurological disease.

NUCLEAR MAGNETIC RESONANCE IMAGING OF THE BRAIN IN MULTIPLE SCLEROSIS

Ten patients with multiple sclerosis (MS) were scanned by means of cranial X-ray computed tomography (CT) with and without intravenous contrast enhancement, and by nuclear magnetic resonance (NMR) using an inversion-recovery sequence. Altogether 19 lesions varying in size between about 7 mm x 5 mm and 13 mm × 8 mm were demonstrated by CT. They were all situated in the periventricular region. Two patients also showed moderate ventricular enlargement. In addition to these abnormalities 112 further lesions were demonstrated on the NMR scans. These lesions varied in size from 4 mm x 3 mm to 12 mm x 7 mm and were particularly well seen in the periventricular region and brainstem. Care is required in the assessment of NMR scans to exclude artefacts, background noise, and mottle as well as normally situated grey matter and partial volume effects from cerebral sulci. NMR nevertheless demonstrates abnormalities in MS on a scale not previously seen except at necropsy.

Nuclear magnetic resonance (NMR) tomography of the normal abdomen.

Abstract:A series of axial transverse and sagittal nuclear magnetic resonance scans through the abdomen are presented demonstrating both solid viscera and blood vessels. The anatomical substrate of the section is explained, and the potential application of these preliminary results in clinical pract

Nuclear magnetic resonance (NMR) tomography of the normal heart.

A series of axial transverse proton nuclear magnetic resonance scans through the heart are presented that demonstrate clear delineation of both the wall and cavity of the constituent chambers. The anatomical substrate of the sections is explained, and the potential applications of these preliminary results in clinical practice are discussed.