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Biomedical subjects

I W McCall

Publications and source records attributed to I W McCall.

At least 19 recordsLinked to original sources
PubMed2006

Cauda equina syndrome presentation of sacral insufficiency fractures.

INTRODUCTION: Sacral insufficiency fractures are a well recognised cause for low back, buttock and groin pain in the elderly. However, over a 4 year period, four patients have presented with symptoms of cauda equina syndrome, who were found on investigation to have acute sacral insufficiency fracture without any other aetiological spinal abnormality. PATIENTS AND METHOD: Four patients who presented to the spinal surgeons of our institution with symptoms of cauda equina syndrome were referred for spinal MR. Sagittal and axial T1 and T2 weighted turbo spin echo sequences of the lower thoracic and lumbar spine were performed on all patients. Subsequent studies included MR of the sacrum supplemented where appropriate by CT and technetium MDP bone scintigraphy. RESULTS: No evidence of a compressive lesion of the lower thoracic or lumbar spine was present in any of the four patients. Dedicated MR examination of the sacrum in these patients revealed unilateral acute insufficiency fractures involving zone 1 from S1 to S3 extending from the sacro-iliac joint to the lateral margin of the sacral foramen. There was no evidence of compression of the sacral nerve roots. The possible mechanism for the symptomatic presentation is discussed. CONCLUSION: Sacral insufficiency fractures should be excluded in elderly or osteoporotic patients presenting with cauda equina syndrome who have no evidence of compression in the thoraco-lumbar MR studies.

Aged↗
PubMed2004

Longitudinal study of vertebral type-1 end-plate changes on MR of the lumbar spine.

The purpose of this study was to investigate the temporal evolution of type-1 end-plate changes on MRI in patients with degenerative disease of the lumbar spine and to evaluate whether any correlation exists between such evolution and the change in patients' symptoms. Forty-four patients with 48 Modic type-1 end-plate changes (low TI signal and high T2 signal) were studied. All patients had an initial and a follow-up non-contrast lumbar MRI with variable intervals between the studies (12-72 months). Severity of the end-plate changes was assessed by eyeball estimation. Correlation with patients' symptoms was studied with the help of the Visual Analogue Score (VAS), Oswestry Questionnaire Score (OQS) and patients' subjective assessment. Of the 48 disc levels with type-1 changes, 18 (37.5%) converted fully to type 2 (high T1 signal and intermediate to high T2 signal), 7 (14.6%) partially converted to type 2, 19 (39.6%) became worse (i.e. type 1 changes became more extensive) and 4 (8.3%) showed no change. Higher average VAS (5.7) and OQS (42.3) scores were noted in patients where there was worsening type-1 change and lower scores (3.8 and 27, respectively) were seen in those where there was conversion to type-2 change. These trends, however, did not reach statistical significance (P values 0.16 and 0.09 for VAS and OQS, respectively). The statistical relationship was stronger after exclusion of patients with confounding factors (i.e. changes in lumbar MRI other than end-plate changes that could independently explain the evolution of patients' symptoms) with P-values of 0.08 and 0.07 for VAS and OQS, respectively. Type-1 end-plate change represents a dynamic process and in a large majority of cases either converts to type-2 change or becomes more extensive. The evolution of type-1 change relates to change in patient's symptoms, but not to a statistically significant level.

Adult↗
PubMed2004

Longitudinal study of high intensity zones on MR of lumbar intervertebral discs.

AIM: To study the temporal evolution of high intensity zones (HIZ) on MRI in patients with degenerative disease of the lumbar spine, and to evaluate whether any correlation exist between such evolution and in patient's symptoms. MATERIALS AND METHODS: HIZs in the MRI of 56 patients were included in the study. Each Patient had an initial and a follow-up scan performed at various time intervals. Scans were assessed for any change in HIZs by two observers (D. M. and I. W. M.). Patients' symptoms were assessed for by visual analogue score (VAS), the Oswestry Questionnaire Score (OQS) and patients' subjective assessment of change in symptoms. Any MRI feature, apart from HIZs, which could independently explain a patient's change in symptoms, was considered to be a confounding factor. Data were analysed separately in the whole group as well as in the group without confounding factors. RESULTS: On follow-up MRI, HIZs were found to have resolved in 17 lumbar disc levels (26.6%), improved in 9 (14%), worsened in 12 (18.8%) and remained unchanged in 26 (40.6%) at lumbar disc levels. Chi-square testing did not demonstrate any correlation between HIZ changes and evolution of patients' subjective symptoms (p = 0.26 for the whole group; p = 0.07 for the group without confounding factors). Similar lack of meaningful relationship was noted between HIZ changes and the VAS and OQS scores. CONCLUSION: We conclude that HIZs either do not change or improve spontaneously in a large proportion of cases over a period of time. Furthermore, there is no statistical correlation between HIZ changes and change in a patient's symptoms.

Adult↗
PubMed2004

Ultrasound measured renal length versus low dose CT volume in predicting single kidney glomerular filtration rate.

Ultrasound measured renal length and CT measured renal volume are potential surrogate markers for single kidney glomerular filtration rate (SKGFR). The aims of this study are to determine: (1) the repeatability of ultrasound measured length and low radiation dose spiral CT measured volume; (2) the relationship between renal length and volume; and (3) whether length and/or volume is a predictor of SKGFR. 69 patients with suspected renal artery stenosis underwent ultrasound renal length measurement, CT evaluation of renal volume and assessment of SKGFR. 40 patients had ultrasound measurement of length and CT evaluation of volume performed twice on two separate visits. 25 patients also had ultrasound measured renal parenchymal thickness and area. The region of interest was drawn around the kidneys and a threshold set to subtract renal peripelvic fat and renal pelvis. The volume from each slice was summed to obtain the total volume for each kidney. The limits of agreement for ultrasound measured renal length were -1.6 cm to 1.52 cm and that for CT renal volume were -33 ml to 32 ml. There was significant correlation between ultrasound measured length and CT volume (r=0.74, p<0.01). Volume was a better predictor of SKGFR (r(2)=0.57) than length (r(2)=0.48). The combined parameters of ultrasound measured length, area and parenchymal thickness were a better predictor of volume (r(2)=0.81) and SKGFR (r(2)=0.58) than ultrasound measured length on its own. The low dose CT technique was reasonably reproducible and renal volume measurements correlate better with SKGFR than length. Ultrasound predictions of renal volume and SKGFR can be improved by incorporating cross-sectional area and parenchymal thickness. Further investigation is required to refine our low dose CT technique.

Glomerular Filtration Rate↗
PubMed2001

MRI detection of unsuspected vertebral injury in acute spinal trauma: incidence and significance.

OBJECTIVE: Multilevel spinal injury is well recognised. Previous studies reviewing the radiographs of spinal injury patients have shown an incidence of 15.2% of unsuspected spinal injury. It is recognised that magnetic resonance imaging (MRI) can identify injuries that are not demonstrated on radiographs. The objective of this study was to determine the incidence and significance of spinal injuries using MRI in comparison with radiographs. DESIGN AND PATIENTS: The radiographs and MR images of 110 acute spinal injury patients were reviewed independently of each other and the findings were then correlated to determine any unsuspected injury. RESULTS: MRI detected vertebral body bone bruises (microtrabecular bone injury) in 41.8% of spinal injury patients which were not seen on radiographs. These bone bruises were best appreciated on sagittal short tau inversion recovery MR sequences and seen at contiguous and non-contiguous levels in relation to the primary injury. CONCLUSION: This level of incidence of bone bruises has not previously been appreciated. We recommend that patients undergoing MRI for an injured segment of the spine are better assessed by MRI of the entire spine at the same time to exclude further injury.

Humans↗
PubMed2000

Intra-articular ganglion cysts of the cruciate ligaments.

Intra-articular ganglion cysts of the cruciate ligaments are associated with non-specific clinical signs and symptoms. Familiarity with the MR appearances in particular is important to make an accurate diagnosis, exclude associated abnormalities, and avoid misdiagnosis.

Anterior Cruciate Ligament↗
PubMed2000

Lumbar herniated disks.

Patients with low back and leg pain require careful evaluation and it is essential that there is correlation between the symptoms and signs of sciatica and the imaging demonstration of nerve root compression or displacement by a disk herniation before invasive therapy is undertaken. The natural history of herniations of the nucleus pulposus is complex and the relationship between the appearances on imaging and low back and radicular pain still has to be completely resolved. Considerable experimental work has been undertaken on the relationship between nerve compression, inflammation, and pain and recent studies on cytokines may lead to more precise pharmacologic therapies. The prime value of MR imaging may be in monitoring disk and nerve root changes in longitudinal studies of patients randomized to different therapeutic programs.

Contrast Media↗
PubMed2000

Effect of Paget's disease of bone on areal lumbar spine bone mineral density measured by DXA, and density of cortical and trabecular bone measured by quantitative CT.

Although bone density may be increased in bone that is affected by Paget's disease, density changes in cortical and trabecular bone and the effect on bone that is apparently unaffected by Paget's disease are relatively unexplored. We have investigated 81 vertebrae (28 affected, 53 unaffected) in 27 patients with Paget's disease, by dual X-ray absorptiometry (DXA) and by quantitative CT (QCT) bone density measurements of trabecular and cortical bone. DXA bone density was high (mean z-score = 1.62, p < 0.001) in vertebrae affected by Paget's disease, but not significantly different from normal in unaffected vertebrae (mean z-score = 0.07, ns). Mean QCT z-score in Paget's vertebrae was 2.07 (p = 0.009) for cortical bone and 1.37 (p = 0.008) for trabecular bone. DXA correlated with QCT cortical values in affected and unaffected bone (r = 0.8 and 0.56, respectively), and with QCT trabecular values (r = 0.72 and 0.48, respectively). There was no significant difference in the slopes for the correlations in affected or unaffected bone. Cortical QCT values are underestimated in Paget's disease compared with physical measurements of density, owing to the computer algorithm used. High DXA values may alert to the possibility of Paget's disease, especially if the value deviates from the expected normal sequence in lumbar vertebrae. Osteoporotic vertebrae may be overlooked if the average value of bone mineral density is taken in the lumbar spine without reviewing each vertebra.

Absorptiometry, Photon↗
PubMed1999

Vertebral intra-osseous chordoma or giant notochordal rest?

Chordomas of the lumbar vertebral bodies are rare. We report an unusual case of an entirely intraosseous chordoma of the fifth lumbar vertebra treated by vertebrectomy. Conventional radiographs and scintigraphy were normal. The lesion was well visualised by MR imaging, but showed only slight sclerosis on CT. We give our reasons for making a diagnosis of chordoma rather than giant notochordal rest and discuss the problems of management resulting from this diagnostic dilemma.

Adult↗
PubMed1999

Spinal infection.

Spinal infection is a significant cause of morbidity. Despite advances in antibiotic treatment regimens, the incidence is not decreasing due at least in part to an increase in 'at-risk' populations, namely the elderly and the immunocompromised. Prompt diagnosis is greatly facilitated by early and appropriate imaging techniques together with microbiological assessment following culture from blood, needle aspirate and biopsy material. This article gives an overview of imaging of spinal infection with an emphasis on MR imaging, which has greatly contributed to early diagnosis, thus allowing implementation of timely appropriate treatment.

Adult↗
PubMed1999

MRI appearances of the infrapatellar fat pad in occult traumatic patellar dislocation.

AIM: A study was undertaken to determine the status of Hoffa's infrapatellar fat pad in instances of acutely dislocated patellae. MATERIALS AND METHODS: The study consisted of MR examinations performed on 18 consecutive patients with acutely dislocated and relocated patellae with a mean interval between injury and MR examination date of 14.8 days (range 1-60 days). An analysis of the attachments and intrinsic signal characteristics of the fat pad was performed for each individual case. RESULTS: Hoffa's fat pad was abnormal in all cases. Shear injury from the inferior pole of the patella was present in 16 cases. Intrasubstance disruption with fluid filled clefts were noted in 12 cases. In 17 cases diffuse oedema of Hoffa's fat pad had occurred. In nine cases the damaged fat pad mimicked a loose body, while in five cases an intra-articular post-traumatic loose body was identified. CONCLUSION: Post-traumatic change in Hoffa's fat pad is a constant secondary MR feature not previously reported, that can be added to the spectrum of indirect findings in cases of occult patellar dislocation. In addition, the MRI distinction between post-traumatic changes in Hoffa's infrapatellar fat pad from loose osteo-chondral bodies can be difficult, requiring further correlative imaging.

Adipose Tissue↗
PubMed1998

Gadolinium-DTPA enhancement of symptomatic nerve roots in MRI of the lumbar spine.

Disc prolapse presenting with sciatica may be associated with enhancement of the symptomatic nerve root following magnetic resonance imaging (MRI) with intravenous gadolinium (Gd)-DTPA. Previous studies have shown, however, that this does not occur in all cases. The aim of this study was to assess the incidence of nerve root enhancement in patients with sciatica and disc prolapse and to try to identify any specific features that might be associated with the phenomenon. A total of 227 patients presenting with low back pain and/or sciatica underwent a MRI study of the lumbar spine with intravenous contrast enhancement. Nineteen of 81 (23.5 %) patients with disc prolapse demonstrated nerve root enhancement. Nerve root enhancement had a highly significant association with sequestrated disc lesions (13/19, 68 %; P < 0.0005), and was primarily seen in the symptomatic ipsilateral nerve root (16/19, 84 %). The sensitivity of nerve root enhancement associated with disc prolapse was 23.5 % with a specificity of 95.9 %, a positive predictive value of 76 % and a negative predictive value of 69.3 %. Nerve root enhancement may be indicative of the symptomatic level but its poor sensitivity negates the routine use of Gd-DTPA in MRI for sciatica.

Contrast Media↗
PubMed1998

Ossification of the posterior longitudinal ligament in Down's syndrome.

Cervical myelopathy in patients with Down's syndrome is not uncommonly the result of atlanto-axial instability, a condition that is caused by ligamentous laxity and which may be associated with congenital osseous anomalies at the occipito-atlanto-axial axis. Ossification of the posterior longitudinal ligament (OPLL) is well described, particularly in the Japanese population, and may be associated with diffuse idiopathic skeletal hyperostosis. This is the first case, to our knowledge, of OPLL occurring in a person with Down's syndrome presenting with myelopathy.

Down Syndrome↗
PubMed1998

Dose-area product readings for fluoroscopic and plain film examinations, including an analysis of the source of variation for barium enema examinations.

This paper contains the results of an investigation undertaken between 1994 and 1996 using dose-area product (DAP) meters for monitoring radiation doses from six types of simple examinations and seven types of complex examinations. Mean hospital DAP levels have been compared with National Reference Levels (NRL), with most departments producing levels lower than NRLs. DAP readings have allowed the proposal of provisional Reference Levels (RL) to be set for simple and complex examinations. The results were also compared with recently published data from the National Radiological Protection Board (NRPB), highlighting those hospitals which need to make changes in radiographic technique. The study of DAP reference doses also confirms that dose levels for complex investigations are clearly related to technique, in terms of screening time and number of films. Although the use of increased screening tube kilovoltage may be relevant, the overall effect is small. The results suggest that there is still a need to optimize the protocols for these examinations. The use of digital equipment has been shown to have a complex effect on dose, particularly in the case of investigations involving both films and fluoroscopy.

Barium↗
PubMed1997

Does the thickness of the vertebral subchondral bone reflect the composition of the intervertebral disc?

Degeneration of the intervertebral disc, seen radiologically as loss of disc height, is often associated with apparent remodelling in the adjacent vertebral body. In contrast, maintenance or apparent increase in disc height is a common finding in osteoporosis, suggesting the properties of the intervertebral disc may be dependent on those of the vertebral body or vice versa. We have investigated this relationship by measuring the radiological thickness of the subchondral bone and comparing it to the chemical composition of the adjacent disc. Sagittal slabs were sampled from lumbar spines obtained at autopsy and X-rayed microfocally. The thickness of the subchondral bone was measured and correlated with the composition of the adjacent intervertebral disc. Eighty-three cadaveric endplates were studied from individuals aged 17-85 years. There was regional variation in thickness of the subchondral bone, being greater adjacent to the annulus than the nucleus, and the endplates cranial to the disc were thicker than those caudal. There was a positive correlation between the thickness of the subchondral bone and the proteoglycan content of the adjacent disc, particularly in the region of the nucleus. A weaker correlation was seen here between water content and thickness, whilst there was no significant correlation at the annulus or between the bone thickness and collagen content. The positive relationship between the radiographic thickness of vertebral subchondral bone and the proteoglycan content of the adjacent disc seen in human cadaveric material could be due to the bone responding to a greater hydrostatic pressure being exerted by discs with higher proteoglycan content than by those with less proteoglycan present. It is suggested that while this is true in "normal" specimens, the relationship becomes altered in disease states, possibly because of changes to the nutritional pathway of the disc, with resultant endplate-bone remodelling affecting the flow of solutes to and from the intervertebral disc.

Adolescent↗
PubMed1996

Neurologic outcome in conservatively treated patients with incomplete closed traumatic cervical spinal cord injuries.

STUDY DESIGN: The neurologic outcomes in patients with conservatively managed incomplete closed traumatic cervical spinal cord injuries was evaluated using the motor scoring system and the Frankel classification. OBJECTIVES: To show that the motor scoring of recovery system combined with functional Frankel grading will make the documentation of final neurologic outcome more accurate for future comparisons of various methods of treatment. SUMMARY OF BACKGROUND DATA: The influence of surgical and pharmacologic methods of treatment on recovery remains debatable. METHODS: Sixty-three consecutive patients with incomplete cervical injuries who were admitted to the hospital within 2 days after injury were included. All patients were treated conservatively with 6 weeks of bedrest and 6 weeks of mobilization with neck support. RESULTS: Five patients had neurologic deterioration, and all but one patient recovered without surgery. The evaluation of 44 patients who were observed for more than 12 months showed that the preservation of sharp sensation below the level of injury was an indicator of a good prognosis in patients whose injuries were classified as Frankel B, and the degree of recovery of these patients according to the motor score system was comparable with that of patients who were classified as Frankel C. All patients classified as Frankel C who did not deteriorate recovered in Frankel grade. All but one of the patients in the Frankel D group recovered full motor power. The degrees of motor deficit and recovery did not correlate with the mechanism or the degree of the injury of the spinal axis. CONCLUSION: Conservative treatment remains a good option for patients with incomplete cervical cord injuries. It is hoped the current study will be a good basis for comparison of the neurologic outcomes of different treatment modalities.

Adolescent↗
PubMed1996

The relative contribution of disc and vertebral morphometry to the angle of kyphosis in asymptomatic subjects.

In order to investigate the relative contributions of vertebra and inter-vertebral disk to kyphosis, a series of 100 asymptomatic healthy women (age range 39-91 years) were studied to evaluate lateral dorsal appearances and possible related parameters of bone loss. Subjects underwent lateral dorsal spine radiography and single photon absorptiometry of the radius. There was a significant decrease in physical height in relation to age (P < 0.001) and this was directly related to an increasing thoracic kyphosis (P < 0.005). The angle of kyphosis was better related to the average anterior disc height (P < 0.001) than to average anterior vertebral height. The vertebral body ratio, however (anterior/posterior height), was more strongly related to angle of kyphosis than was disk ratio. The results also showed a fall in the proximal and distal radial bone mineral content with age (P < 0.001). These findings suggest that dorsal kyphosis as part of the ageing process may be as closely related to the physical integrity of the disc as to the vertebral body. Hence, therapy for age related bone mineral loss may have limited effect on a kyphotic deformity of the dorsal spine in otherwise asymptomatic patients.

Absorptiometry, Photon↗