PubMed Health⌕ Search

Biomedical subjects

G M Bydder

Publications and source records attributed to G M Bydder.

At least 109 records · Page 6Linked to original sources
PubMed1985

Nuclear magnetic resonance imaging in the diagnosis and follow-up of neonatal cerebral injury.

NMR scanning is feasible in the newborn period, and is capable of diagnosing most of the problems in this age group, but its general application presents a number of difficulties at present. It cannot be transported to the bedside. Adequate monitoring of ill patients is difficult, and scanning takes a relatively long time. The neonatal brain has an extremely high water content, and NMR scanning procedures require adaptation to apply to these conditions. NMR imaging, however, has already proved extremely useful in the follow-up of neonatal insults. Repeated scanning is possible after closure of the fontanelle without subjecting the infant to ionizing radiation. The scans are able to demonstrate not only the anatomic changes associated with the various lesions, but also how these might affect myelination. Development of better coils and more suitable scanning sequences for neonates and infants are needed to improve image quality and establish the normal range of T1 and T2 values and the normal range of myelination at various ages. Further studies will also establish whether the changes in myelination primarily reflect the pathologic processes occurring in the tissues, such as the amount of gliosis, or are a marker of functional involvement.

Brain↗
PubMed1984

Intravenous chelated gadolinium as a contrast agent in NMR imaging of cerebral tumours.

NMR imaging was performed on 12 patients with cerebral tumour before and after administration of intravenous gadolinium diethylene triamine penta-acetic acid (DTPA) (0.1 mmol/kg). Contrast enhancement was seen in all cases. Ring enhancement was most frequent (7 cases) but central, linear, patchy, and diffuse enhancement were also seen with both inversion-recovery and spin-echo sequences. The degree of enhancement was greater than that seen with X-ray computed tomography (CT) in 8 cases, equal to it in 3 cases, and less in 1 case. NMR distinguished between tumour and peritumoral oedema to the same extent as did CT. No side-effects were encountered and there was no significant change in urea, creatinine and electrolytes, liver function tests, blood coagulation, or urine testing after administration of gadolinium-DTPA. Gadolinium-DTPA is likely to be of considerable value in NMR imaging of the brain.

Adult↗
PubMed1984

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.

Brain Neoplasms↗
PubMed1984

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.

Abdomen↗
PubMed1984

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.

Adolescent↗
PubMed1984

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.

Budd-Chiari Syndrome↗
PubMed1984

Magnetic resonance imaging of the brain.

The brain has been the principal area of clinical interest in proton MR imaging since the first clinical scans in 1980. The technique has evolved rapidly and promises to supplement x-ray CT in a number of clinical applications. Recent research advances, such as the development of paramagnetic contrast agents, are now being applied in clinical practice and show considerable promise.

Adult↗
PubMed1984

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.

Brain↗