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Biomedical subjects

C E Freer

Publications and source records attributed to C E Freer.

At least 19 recordsLinked to original sources
PubMed1998

Evaluation of carotid endarterectomy with sequential MR perfusion imaging: a preliminary report.

BACKGROUND AND PURPOSE: Current indications for carotid endarterectomy are determined by balancing the relative risks of surgery with the benefits of reduced risk of subsequent stroke. Our purpose was to use MR perfusion imaging to assess patients being considered for carotid endarterectomy and to monitor sequential changes in MR perfusion characteristics after surgery. In particular, we wished to determine whether this technique could be used to detect changes that might be related to post-carotid endarterectomy hyperemia. METHODS: We used a single-section gradient-recalled echo sequence to investigate 14 patients being examined before possible surgery for carotid artery disease. In the 12 patients in whom carotid endarterectomy was performed, sequential studies were performed 3 to 5 days after surgery and at 3 months. Analysis of bolus-arrival-time (BAT) images was performed. RESULTS: Significant delays in preoperative BAT images of 0.89 seconds (range, 0.05 to 3.22 seconds) were apparent between hemispheres. Excluding the two patients with contralateral internal carotid artery (ICA) occlusion, early arrival, possibly indicating postoperative hyperemia, was seen in five patients immediately after carotid endarterectomy but resolved within 3 to 5 months after surgery. CONCLUSION: MR perfusion imaging shows differences in BAT between hemispheres in patients with ICA stenosis. Changes in perfusion characteristics after carotid endarterectomy are complex, and early BAT on the operative side can occur soon after endarterectomy in over half those patients without an occluded contralateral vessel. The significance of these findings with regard to patient outcome and risk of postoperative hyperemia requires further investigation.

Aged↗
PubMed1996

Neuroradiological findings in primary progressive aphasia: CT MRI and cerebral perfusion SPECT.

Primary progressive aphasia (PPA) is defined as progressive decline in language for 2 or more years with preservation of activities of daily living and general cognitive functions. Whereas the clinical features of this syndrome have been well documented, the neuroradiological findings have not been studied systematically. We studied 13 patients with PPA retrospectively: 10 underwent CT, 12 MRI and 12 cerebral perfusion studies using 99mTc-HMPAO SPECT.CT and MR images were scored for focal atrophy by two independent assessors. Initial qualitative assessment of SPECT images was confirmed by quantitative analysis. CT was normal in 5 patients. Focal atrophy, affecting predominantly the left temporal lobe, was seen in 4 of 10 patients on CT, and 10 of 12 on MRI. Atrophy was localised primarily to the superior and middle temporal gyri on MRI. All 12 patients who underwent SPECT had unilateral temporal lobe perfusion defects, in 2 patients of whom MRI was normal. CT is relatively insensitive to focal abnormalities in PPA; MRI and SPECT are the imaging modalities of choice. MRI allows accurate, specific localisation of atrophy within the temporal neocortex. SPECT may reveal a functional decrease in cerebral perfusion prior to establishment of structural change.

Adult↗
PubMed1996

MR sialography. Work in progress.

PURPOSE: To develop a noninvasive method for demonstrating the main salivary gland duct systems. MATERIALS AND METHODS: The authors developed a magnetic resonance (MR) imaging protocol that uses a heavily T2-weighted (echo time, 750 msec), fat-suppressed pulse sequence and rapid acquisition with relaxation enhancement. The technique was optimized to depict fluid within a two-dimensional thick slab. A preliminary evaluation was performed by examining the major salivary gland ducts in 10 asymptomatic volunteers and three symptomatic patients with known salivary duct abnormalities. RESULTS: The main parotid gland ducts were clearly demonstrated in all volunteers. The submandibular ducts were visible in all cases, although not always on projection images. In the three patients, the MR technique clearly demonstrated bilateral sialectasis, a calculus obstructing the left submandibular duct, and a fluid-filled ranula, respectively. CONCLUSION: Preliminary work indicates that this MR technique can successfully demonstrate both normal and abnormal parotid and submandibular gland duct systems and has several advantages over conventional x-ray sialography.

Adolescent↗
PubMed1995

CT of a peripatetic intracranial foreign body.

We report the CT appearances of a low-velocity missile that lodged within the brain and which subsequently migrated spontaneously back along the entry path. We review the literature of similar instances of migration and draw conclusions about the presurgical radiological management.

Adolescent↗
PubMed1993

Pictorial review: benign and malignant enlargement of the pterygo-masseteric muscle complex.

Seven cases of unilateral enlargement of the pterygoid and/or masseter muscles due to haemangioma (1), benign masseteric hypertrophy (2), rhabdomyosarcoma (2), leukaemic infiltration (1) and non-Hodgkin's lymphoma (1) are presented. The differential diagnosis of pterygo-masseteric muscle enlargement is outlined and the usefulness of computed tomography (CT) discussed.

Adolescent↗
PubMed1991

Magnetic resonance imaging of the head and spine: effective for the clinician or the patient?

OBJECTIVES: To test how the results of magnetic resonance imaging influence clinicians' diagnoses and management plans for patients with cranial and spinal problems and to assess changes in the quality of life of these patients. DESIGN: Survey of patients undergoing cranial and spinal magnetic resonance imaging with questionnaires about diagnoses and intended management plans before and after imaging and quality of life questionnaires at the time of imaging and again four months later. SETTING: Regional magnetic resonance imaging and spectroscopy unit. SUBJECTS: 100 consecutive patients referred for cranial imaging in early 1989; 100 similar patients referred for spinal imaging. MAIN OUTCOME MEASURES: Changes in clinicians' leading diagnoses after magnetic resonance imaging and their confidence in these diagnoses; changes in intended management plans; assessment of the contribution to the future management of the patient; changes in patients' quality of life. RESULTS: Magnetic resonance imaging altered the clinicians' leading diagnoses in 35 of 169 (21%) cases. The clinicians became more confident about their leading diagnoses in 90 of 167 (54%). There was a change in management plan in 113 of 182 (62%). The clinicians considered that magnetic resonance imaging made an important contribution to management in 119 of 162 (73%) patients. Overall, the patients' quality of life was unchanged at the four month assessment. CONCLUSIONS: Magnetic resonance imaging of patients with cranial and spinal problems influences clinicians' diagnoses and management plans, but the quality of life of these patients remains unchanged.

Adolescent↗
PubMed1991

Localized in vivo proton spectroscopy of the human kidney.

In vivo 1H spectroscopy using the STEAM sequence for localization has been applied to the human kidney in normal volunteers and subjects with successful renal transplants. We show that, within the resolution of our measurements, trimethylamines are present in the spectra from some of the subjects and absent from others. The prominent peak seen at 5.8 ppm in the spectrum is identified as that from urea and not lipid, as previously suggested.

Humans↗
PubMed1991

Magnetic resonance imaging: when is one sequence sufficient?

We have studied 100 patients undergoing magnetic resonance imaging (MRI) in eight well-defined clinical problems. The relative values of the clinical details and the initial imaging sequence in reaching the final MR diagnoses were assessed. For each patient, two radiologists independently predicted the likely radiological findings from the clinical details. They then assessed the radiological appearances shown by the initial imaging sequence (which was chosen according to the clinical problem). Lastly, they made a final interpretation using all the available information. Prediction of likely radiological abnormalities from the clinical details proved unreliable. However, the radiological assessment of the initial imaging sequence was reliable for clinical problems related to the pituitary fossa, posterior fossa, internal auditory meatus and for suspected multiple sclerosis. In these patient groups additional sequences might be reserved for those with equivocal findings. Conversely, assessment of the initial imaging sequence proved unreliable compared with the full radiological assessment for clinical problems in the lumbar spine, the axilla and the knee. This study has led us to reduce the number of sequences performed for some clinical problems, with a commensurate increase in the throughput of patients.

Clinical Competence↗
PubMed1991

Radiology for cochlear implants.

One fifth of patients selected for cochlear implants have such bony irregularities in the cochlear duct that full insertion of a multichannel electrode array is impossible. Three cases of cochlear deafness are presented where pre- and post-operative radiology played an important part in the management. Standard CT at 2 mm cuts is compared with ultra high resolution CT at 1 mm cuts. The pitfall of poor definition is that the inexperienced surgeon may find himself unexpectedly drilling out an obliterated cochlear duct. Sections 30 degrees caudal to Reid's infra orbito-meatal base line at 1 mm intervals give maximum information for minimum radiation. Plain films show the placement of individual platinum electrode contacts in relation to the spiral 'frequency map' of the cochlea. This is vital information for the audiologist who has to route specific frequencies to specific sites within the ear for a good hearing result.

Adult↗
PubMed1991

Measurement of regional left ventricular function using labelled magnetic resonance imaging.

A technique for assessing regional left ventricular function using magnetic resonance imaging is described. Spatial modulation of magnetization (SPAMM) is effected immediately before images are obtained at various intervals during the cardiac cycle using a modified field echo even rephasing technique (FEER). By performing such modulation in two planes, a grid pattern of labelling can be produced across the image. On the resulting labelled short axis images of the left ventricle, the systolic increase in thickness (thickening) and decrease in length (shortening) of different regions of myocardium can then be measured. The findings in five normal volunteers are presented. Radial shortening was twice as great in the endocardium (mean 20.4%, standard deviation (SD) 5.7) than in the epicardium (mean 10.2%, SD 5.5) and appears to offer more promise as a marker of regional function than simple thickening (mean 9.8%, SD 13.6).

Adult↗
PubMed1990

Pituitary computed tomography: is contrast enhancement necessary?

Direct coronal computed tomography of the pituitary fossa, before and after enhancement with intravenous contrast medium, was performed on 25 consecutive patients with hyperprolactinaemia. The images were viewed separately by two independent observers and the pituitary height, width and contour, and the visibility of the infundibulum, optic chiasm and hypothalamus were assessed. The presence and size of any possible pituitary tumour was recorded. The administration of intravenous contrast medium made no significant difference to the pituitary measurements, the visibility of the infundibulum of hypothalamus, or the detection of possible pituitary tumours. There was an inconsistent improvement in the visibility of the optic chiasm following enhancement. The arguments against an unenhanced examination are discussed and refuted. It is proposed that routine administration of intravenous contrast medium is unnecessary when investigating moderate hyperprolactinaemia.

Contrast Media↗
PubMed1990

Axillary fibrosis or recurrent tumour. An MRI study in breast cancer.

Magnetic resonance imaging was performed in 35 patients with breast carcinoma in an attempt to elucidate the cause for arm oedema or neurological symptoms. In each patient the clinician was asked to predict at the outset whether tumour recurrence or radiation fibrosis was more likely on clinical grounds. MRI demonstrated features compatible with fibrosis in 21 and tumour recurrence in 10; the MRI findings were equivocal in four patients. The range of these appearances is described and demonstrated. The MRI findings were at gross variance with the clinical opinion in 10 patients, upgrading eight patients to tumour recurrence and downgrading two to radiation fibrosis. Although histological confirmation is only available in three patients, corroborative evidence (that is repeat MRI, clinical follow up) is presented which suggests that the MRI interpretation was correct in the remaining patients. MRI can provide a working diagnosis in these patients; this allows a more rational approach to treatment than a diagnosis based on clinical examination alone.

Adult↗
PubMed1990

Magnetic resonance imaging of the brain and brain-stem in elderly patients with dizziness.

Twenty elderly patients (mean age 82 years) with dizziness were examined by magnetic resonance imaging (MRI). The findings have been compared with those from nine healthy subjects of similar age who acted as a control group. The technique proved acceptable to all these patients, and in the majority (65%) the overall radiographic quality of the resulting images was adequate, good or excellent. Nineteen of the 20 patients showed evidence of abnormal high signal intensity within white matter, often close to the frontal horns but also more widely scattered within the cerebral hemispheres; similar lesions were seen in the brain-stem in eight of the patients. However these white matter changes were equally prevalent in the control group. No cause for dizziness has been shown by MRI.

Aged↗
PubMed1989

Computed tomography in the diagnosis of malignant brain tumours: do all patients require biopsy?

A proportion of patients with computed tomographic (CT) scan appearances of malignant brain tumour undergo conservative management, despite the absence of histological confirmation of the diagnosis. Concern that this policy risked misdiagnosing a benign tumour prompted us to examine the accuracy of CT scanning in diagnosing malignant lesions. The study was designed to determine whether within a group of 300 patients with intracerebral mass lesions of known pathology, two sub-groups existed: one with appearances so specific for malignant glioma that biopsy was unnecessary, and the other in which the appearances were characteristic of malignancy, though not specific for glioma. Three neuroradiologists independently reviewed the CT scans, together with brief clinical details. When diagnosing malignant tumours, all made errors: nine benign lesions were considered to be malignant. When diagnosing malignant glioma, one neuroradiologist made errors, but the other two adopted a more cautious approach and were accurate. The restricted a "certain" diagnosis to about one in five scans considered to show malignant tumour. Those diagnosed specifically as malignant glioma were intrinsic, irregular, mixed density lesions, exhibiting variable enhancement and infiltrating the peri-ventricular tissues, especially the corpus callosum. Using these criteria, they could correctly identify a small proportion of patients with malignant gliomas. In all other patients, biopsy remains the only means of obtaining a definitive diagnosis.

Biopsy↗
PubMed1989

The anatomy of the first sacral nerve root sheath shown by computed tomography.

Analysis of 25 patients with normal computed tomographic appearances at the lumbosacral junction revealed wide variation in the anatomical level at which the first sacral nerve root sheaths were seen emerging from the theca. In nine patients (36%), the S1 nerve root sheaths were first recognized at the level of the lumbosacral disc. In 14 patients (56%), the sheaths emerged cranial to the disc; it is possible that these patients may be more prone to neurological complications related to disc or facet joint disease, especially if the sheath is laterally sited within the lateral recess. Conversely, that minority of patients (two, 8%) in whom the root sheaths emerge caudal to the disc level may be relatively protected from neurological complications.

Adolescent↗
PubMed1988

Primary lymphoma of the central nervous system: experience at Addenbrooke's Hospital, Cambridge.

A series of 22 cases of primary intercerebral lymphoma are reported. The clinical presentation and natural history were similar to high grade glioma in adults. There was a male to female ratio of 2.7:1, and a mean age at presentation of 63 years (range 47-72 years). Single masses were present in 77%, and the frontal lobe was the most frequently involved (64%). Treatment regimes included varying combinations of surgical resection and cranial irradiation. Sixteen patients have died, twelve due to recurrent or persistent intracerebral disease. The median survival was ten months. Six patients are still alive at 52, 12, 10, 9, 6 and 4 months. Failure to control the intracranial tumours was the main cause of death. Significant debulking of the tumour was the single most important prognostic factor, although a good initial response to steroids was also favourable. No patient developed spinal deposits. Even when there is a good response to radiation and prolonged survival, the quality of life may be poor: in this series only five out of 22 patients (23%) returned to a normal life. Radiation dosage and the indications for spinal treatment are discussed.

Aged↗
PubMed1988

Ultrasound in the diagnosis and management of spinal and sacral tumours.

Spinal and sacral tumours present not only a challenge in their initial diagnosis but also in their subsequent progress. Imaging of these tumours usually requires intrathecal contrast medium but where an acoustic window is present ultrasound may be used. The ability and clinical value of ultrasound has been assessed in 13 examinations on 10 patients. Although there was no clinical advantage in three and only equivocal advantage in one, ultrasound provided unequivocal benefit in five examinations and was synergistic in four. The technique is simple, quick and well tolerated.

Adult↗