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Biomedical subjects

J P Stack

Publications and source records attributed to J P Stack.

34 records · Page 2Linked to original sources
PubMed1991

Imaging of intramedullary tumour spread in osteosarcoma. A comparison of techniques.

The level of bone resection for osteosarcoma depends on the pre-operative evaluation of the extent of intramedullary tumour. We compared the accuracy of magnetic resonance imaging (MRI), computerised tomography (CT), and isotope bone scanning with the actual extent of the tumour in the resected specimens from 34 patients with primary osteosarcoma of a long bone. The extent of medullary tumour was defined accurately in 23 of 24 MRI scans (96%) and 24 of 32 CT scans (75%). A flexion contracture of a joint close to the tumour was an important cause for inaccurate measurements from both MRI and CT scans. Isotope bone scanning was inaccurate: its role is now confined to detecting skeletal metastases and skip lesions.

Adolescent↗
PubMed1990

A comparison of modern imaging modalities in osteonecrosis of the femoral head.

Eleven symptomatic and seven asymptomatic patients, considered to be at high risk of osteonecrosis of the hip, were studied using plain radiography, scintigraphy, computed tomography (CT) with multiplanar reconstruction (MPR), and magnetic resonance imaging (MRI), to determine the precise roles of the various imaging modalities in detecting and staging femoral head osteonecrosis, and to evaluate the incidence in an asymptomatic high-risk patient group. Osteonecrosis was best detected by MRI and was particularly useful for the diagnosis of early disease when other imaging modalities were negative. It is recommended that MRI be performed for the detection of early osteonecrosis, while CT/MPR be used for accurate staging and treatment planning in the established disease.

Adult↗
PubMed1990

Moyamoya disease--imaging with magnetic resonance.

We report a case of moyamoya disease in a young adult female, in whom the initial clinical and radiological features were considered to be compatible with multiple sclerosis. The subsequent development of cerebral infarction led to the typical moyamoya features being found on carotid angiography. Magnetic resonance imaging (MRI) features of dilated collateral arteries were then recognized, and the initial MRI findings considered to represent demyelination were reinterpreted as areas of infarction. Although rare, moyamoya disease should be considered in the differential diagnosis in young patients presenting with symptoms and signs suggestive of multiple sclerosis. The diagnosis may be suggested by typical MRI findings.

Adult↗
PubMed1990

The role of discography in lumbar disc disease: a comparative study of magnetic resonance imaging and discography.

This study reviews prospectively a series of 29 patients who were examined by magnetic resonance imaging (MRI) and discography for degenerative disc disease. All had persistent low-back pain and non-diagnostic initial investigations, including plain films, myelography and/or computed tomography (CT). The imaging characteristics for degenerative disc disease correlated in 65 out of 73 intervertebral levels. All symptomatic discs were degenerate on both MRI and discography. Features of degenerative disc disease on MRI were assessed retrospectively, with a view to identifying the symptomatic level as defined by discography. MRI could not reliably detect this level, particularly in those with multi-level degenerative disc disease. Positive reproduction of symptoms at discography was the criteria used for surgery. All 12 patients in this group had posterior spinal fusion performed. Nine improved and three were unchanged. Of the ancillary features associated with disc degeneration, only a bulging annulus fibrosis proved to be of any value on MRI. Nonetheless, MRI should be used as the primary investigation in this patient group as it can lead to a marked reduction in the number of disc levels requiring injection.

Adult↗
PubMed1990

Breast disease: tissue characterization with Gd-DTPA enhancement profiles.

Magnetic resonance (MR) imaging of the breast is currently of limited value because of lack of specificity. Enhanced MR imaging with gadolinium diethylenetriaminepentaacetic acid (DTPA) has been shown to be helpful in the further characterization of breast tissue. This prospective study attempted to differentiate benign and malignant breast disease with a dynamic enhancement technique. Bolus injection of Gd-DTPA and a short MR imaging time were used to examine 18 patients with a palpable breast mass. Construction of enhancement profiles helped effectively differentiate benign and malignant lesion (P less than .001). Dynamic MR imaging shows promise for the further characterization of breast tissue and, particularly, identification of breast carcinoma.

Adult↗
PubMed1989

Osteosarcoma: use of MR imaging and MR spectroscopy in clinical decision making.

Magnetic resonance (MR) imaging was performed on 14 patients with histologically proved osteosarcoma (mean age, 14.4 years). There was excellent correlation of intramedullary tumor extent as determined with MR imaging and pathologic examination (r = 99%). This was facilitated by the presence of a chemical shift artifact at the tumor-marrow interface on the T1-weighted images. The correlation between CT and pathologic findings was not as good (r = 84%). In a single patient, however, a 10-cm length of sclerotic bone was incorrectly interpreted as being tumor. If this case is excluded, the correlation between CT and pathologic findings improves significantly (r = 96%). T2-weighted images were optimal in demonstrating soft-tissue bulk and breach of the epiphysis or cortex. Vascular involvement was also readily defined. The T2 value of the tumor soft-tissue component decreased in patients who were deemed to have responded well to therapy. Two patients with very high T2 values after chemotherapy developed wide-spread metastatic disease and died. Phosphorus-31 MR spectroscopy of five patients with osteosarcoma showed elevated levels of phosphomonoesters (PMEs), inorganic phosphate (Pi), and phosphodiesters (PDEs). PME and PDE peak areas decreased in three patients after chemotherapy, while Pi peak areas increased.

Adolescent↗
PubMed1988

Gadolinium-DTPA as a contrast agent in magnetic resonance imaging of the brain.

One hundred patients with CT-proven intracranial disease have been studied by magnetic resonance imaging (MRI) before and after intravenous injection with Gadolinium-DTPA (Gd-DTPA), in order to assess the role and clinical efficacy of Gd-DTPA. T2-weighted spin echo sequences, although sensitive to the detection of intracranial disease, in general fail to differentiate macroscopic tumor from oedema. Following Gd-DTPA, T1-weighted spin echo sequences in primary tumours demonstrated a variable degree of contrast enhancement unrelated to histological type. Small tumours, especially acoustic neuromas and meningiomas in the posterior fossa, were rendered more conspicuous. Optimum time for scanning was between five and 25 min following injection for all lesions except those adjacent to normal enhancing structures such as nasal/sinus mucosa and pituitary gland when delayed scans up to 45 min were necessary. No differences were observed between the 0.1 and 0.2 mmol/kg Gd-DTPA concentrations used and no complications attributable to Gd-DTPA were detected. Clinical advantages of Gd-DTPA include shorter scan times, macroscopic tumour/oedema separation and improved detection of certain tumours, particularly acoustic neuromas.

Adolescent↗
PubMed1988

Plexiform trigeminal neurofibroma.

Neurofibromas of the trigeminal nerve are uncommon tumours which usually present in patients in the third or fourth decade of life as a localised mass in the posterior or middle cranial fossa. A case is described of a plexiform neurofibroma of this nerve with unusual clinical and radiological features.

Adult↗
PubMed1988

Magnetic resonance imaging of the mini-pig heart: the effect of gadolinium-DTPA on normal myocardium.

The effect of gadolinium-diethylene-triamine-penta-acetic acid (Gd-DTPA) on normal, mini-pig myocardium was investigated with magnetic resonance imaging. Results indicate that intravenous administration of Gd-DTPA produces a significant enhancement of mini-pig myocardial signal intensity, which in all cases was maintained in excess of 50 min. No significant enhancement was demonstrated in skeletal muscle.

Animals↗
PubMed1988

Magnetic resonance imaging of acoustic neuromas: the role of gadolinium-DTPA.

Magnetic resonance imaging (MRI) was performed in 20 patients with evidence on computed tomography (CT) of 21 acoustic neuromas before and after intravenous administration (0.1-0.2 mmol/kg body weight) of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA). Multi-section spin-echo (SE) sequences of varying repetition (TR) and echo (TE) times were performed in the transverse and coronal planes with a section thickness of 10 mm. All acoustic neuromas displayed marked enhancement on the T1-weighted (short TR/TE) SE sequence post-Gd-DTPA. The intrameatal component was particularly well demonstrated compared with non-enhanced magnetic resonance (MR) images and contrast-enhanced CT. Identification of intrameatal tumour was difficult on T2-weighted SE images and one tumour was not identified on the T1-weighted SE sequence prior to Gd-DTPA. Four of five intrameatal tumours measuring less than 8 mm could only be demonstrated on CT by using CT air meatography. Extrameatal tumour extension was demonstrated on contrast-enhanced CT, although the assessment of brain-stem involvement and displacement was not as clearly seen as on coronal MR images. In two patients with large acoustic neuromas and a cyst, the true relationship of the cyst to the tumour could only be identified on the post-Gd-DTPA scan. Magnetic resonance imaging with gadolinium-DTPA is a relatively quick, safe, well tolerated and effective method for the diagnosis of acoustic neuroma.

Adolescent↗
PubMed1987

Trigeminal nerve tumor: comparison of CT and MRI. Case report.

Benign tumors of the middle fossa components of the trigeminal nerve are rare. The authors describe the case history, radiological investigation, and operative findings of a patient with a large trigeminal neurofibroma of the middle fossa. The unusual mode of presentation is discussed. Valuable information was provided by magnetic resonance imaging prior to successful removal of this tumor.

Adult↗
PubMedDate not supplied

Congenital absence of extraocular muscles: MR demonstration.

We describe a case of an infant with complete congenital absence of the extraocular muscles, noted at surgery and confirmed by multiplane MR, which found no evidence of extraocular muscle tissue. This almost certainly represents an extreme form of bilateral congenital fibrosis syndrome.

Humans↗
PubMedDate not supplied

MR diagnosis of haemorrhagic cystic renal cell carcinoma.

OBJECTIVE: We report two cases of cystic renal masses considered indeterminate on sonography and CT, in which haemorrhagic contents were demonstrated on MRI. MATERIALS AND METHODS: Spin echo T1-weighted axial and coronal (TR 700 ms; TE 17 ms) and T2-weighted axial (TR 3,000 ms; TE 90 ms) upper abdominal scans were obtained on a 1.5 T MR machine. RESULTS: Cyst contents were of high signal on both T1- and T2-weighted sequences, indicating internal haemorrhage, which was confirmed at surgery. CONCLUSION: There is a high propensity for haemorrhagic renal masses to mask carcinoma. By distinguishing blood from other contents, MRI had a noninvasive role in diagnosis and further management.

Carcinoma, Renal Cell↗
PubMedDate not supplied

Magnetic resonance imaging in the pre-operative assessment of closed spinal dysraphism in children.

Magnetic resonance imaging (MRI) was used in the pre-operative assessment of closed spinal dysraphism in 61 paediatric patients. There were 25 cases of tethered cord, 6 of retethering at the site of myelomeningocele repair, 15 cases of diastematomyelia, 12 cases of lipomyelomeningocele, and 1 case each of dermal sinus, dermoid cyst and neurenteric cyst. MRI was found to have accurate correlation with surgical findings in all cases of tethered cord, and diastematomyelia. In cases of re-tethering at the site of previous myelomeningocele repair, while it was a significant advance on previous imaging techniques precise delineation of neural tissue and discrimination from post-operative fibrosis was frequently not possible. Imaging of dorsal lipomyelomeningoceles also correlated with surgical findings and provided accurate pre-operative information. However, the accuracy and pre-operative detail in cases of transitional and terminal lipomyelomeningoceles was disappointing.

Adolescent↗
PubMedDate not supplied

A magnetic resonance imaging study of centric maxillomandibular relation.

The authors conducted research to determine the structural relationships of the craniomandibular articulation that resulted when a mandibular reference position was established. A noninvasive clinical method was used to identify and record centric maxillomandibular relation in normal subjects and a suitable reference position in subjects with derangements of the craniomandibular articulation. The reference positions were checked for repeatability. Magnetic resonance imaging was used to determine the intraarticular relationships resulting from application of the clinical techniques. The normal subjects conformed well to the 1987 "Glossary of Prosthodontic Terms" definition, with the mandible close to first-tooth contact. In subjects with deranged articulations, the condyle was always in an abnormal relationship on the affected side in the reference position, and there were many intersubject variations.

Adolescent↗