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Biomedical subjects

I W McCall

Publications and source records attributed to I W McCall.

At least 37 records · Page 2Linked to original sources
PubMed1996

Influence of dose reduction recommendations on changes in chest radiography techniques.

A previous dosimetric study on chest radiography identified ways to reduce patient entrance surface dose (ESD). This present study was designed to monitor changes that had occurred in the use of applied potential and film-screen sensitivity, after a series of recommendations were issued. The study falls into two parts: (1) an assessment of the impact of the recommendations and (2) what factors were responsible for change. Where changes had occurred, exposure factors were collected for 30 patients per tube and the mean ESD was calculated for each tube. Intercomparison (r = 0.93, p < 0.001) was made between calculated and measured (TLDs) values of mean ESD for 10 X-ray units, to ensure that the calculated values provided accurate estimates of the new mean ESDs. 89% of units previously monitored for patient ESD now use average applied potentials greater than 90 kVp and 51% are using film-screen sensitivities of 400. The mean ESD has been reduced on average by 47%, from 0.15 mGy to 0.08 mGy. It has been estimated that the annual collective dose from diagnostic radiology procedures in 30 hospitals in the West Midlands has been reduced by a value in excess of 40 man Sv. Reasons for change could be attributed to some of the following factors: (a) a knowledge of dose levels in comparison with other centres; (b) personal contact with departments; (c) feedback in terms of results and dose savings and (d) positive encouragement to make changes.

Humans↗
PubMed1995

Hemodynamic alterations in the paravertebral venous plexus after spinal injury.

PURPOSE: To assess the prevalence of altered venous hemodynamics after spinal cord injury. MATERIALS AND METHODS: The authors performed venography in 200 ambulant patients and 107 patients with spinal injury. The hemodynamic characteristics of the paravertebral venous plexus were documented after pedal injection of contrast material. The hemodynamic and clinical data were correlated in patients with spinal cord injury. RESULTS: Abnormal venous return via the paravertebral venous plexus in the absence of iliac or inferior vena caval occlusion was shown in 73 (68%) of the 107 patients with spinal injury. This paravertebral venous flow route is not related to the time between injury and examination. It was demonstrable in the early as well as late post-traumatic period and was reproducible at subsequent examinations. The paravertebral venous flow route was more commonly seen in cervical than thoracolumbar injuries and was closely related to the severity of neurologic deficit (P = .0012). CONCLUSION: Abnormal vertebral venous hemodynamics occur in most patients with spinal cord injury and are more likely to occur in patients with complete neurologic deficit and cervical injury.

Case-Control Studies↗
PubMed1995

Short communication: a lateral will do?

Efforts to reduce the dose of diagnostic medical irradiation by applying selective criteria for radiographic examinations have been addressed by the Royal College of Radiologists in their Guidelines. Reduction of the number of views of an area has also been suggested by some authors. Deviating from one of the fundamentals of skeletal radiology which requires at least two views of any part of the skeleton may lead to misdiagnosis. This concept is considered in relation to the lumbar spine. Continued routine acquisition of at least two views for the radiographic examination of the lumbar spine is stressed.

Humans↗
PubMed1994

MRI of the knee following prosthetic anterior cruciate ligament reconstruction.

The MRI appearances of the knee in 30 patients with residual symptoms following active biocomposite (ABC) reconstruction of the anterior cruciate ligament were prospectively correlated with the clinical and arthroscopic findings. The variable MR features of the neo-ligament depend on the integrity of the prosthesis, the degree and extent of tissue ingrowth, and the time delay between surgical placement and MRI. The ABC ligament gives a uniform low signal when freshly placed, which is slowly lost by the incorporation of tissue ingrowth and therefore the loss of MR visualization of the ABC ligament is not synonymous with failure. Analysis of the imaging features suggests that a neo-ligament emerging through the tibial tunnel either at or posterior to the mid point of the AP diameter of the tibia is likely to be intact (P = 0.008) compared with one placed anteriorly. The presence of an effusion (64%) indicates that symptoms are more likely to be due to other internal mechanical derangement rather than failure of the neo-ligament. Meniscal tears were seen in 67% while osteo-chondral defects were noted in 30% of all patients. Excellent correlation with arthroscopic findings was established confirming intact neo-ligaments in 16 replacements. MRI in the post-operative period detects rectifiable problems before the development of irreversible mechanical damage and re-rupture of the neo-ligament, but a thorough MRI technique needs to be utilized in examining the entire knee.

Adult↗
PubMed1993

Sonographic diagnosis of heterotopic bone formation in spinal injury patients.

A variety of stimuli including neurological insult may provoke primitive mesenchymal cells to differentiate into bone forming cells. Such a sequel following spinal cord injury can delay rehabilitation, enhance the spasticity and reduce the range of movement in the affected joint. It is characterised by an initial inflammatory phase followed by heterotopic bone formation. The early inflammatory lesion clinically mimics deep vein thrombosis, a developing pressure sore, infection, and tumour. An early diagnosis at a time of clinical uncertainty, before the plain radiographic features develop, has distinct advantages and therapeutic implications. The unique pathological evolution and maturation of the lesion is clearly demonstrated by sequential sonographic (ultrasonic) assessment with depiction of the 'zone phenomena' seen on histology. Sonographic scans in 7 spinal injury patients proved diagnostic, before there was radiographic evidence of bone formation, and confidently excluded HBF in a further 18 patients without any false negative results.

Adult↗
PubMed1993

The patello-femoral joint--a critical appraisal of its geometric assessment utilizing conventional axial radiography and computed arthro-tomography.

In the quest for treatable causes of anterior knee pain, plain film skyline views of the patello-femoral joint are requested, often in 30 degrees, 60 degrees and 90 degrees of flexion, to assess the functional relationships of the joint. Patello-femoral malalignment predisposes to recurrent subluxation and dislocation, articular cartilage damage and premature degenerative change. The aim of this study is to evaluate critically, by comparative assessment, the information provided by skyline views and axial computed arthro-tomography (CTA). Measurements of the patello-femoral angle (assesses patellar tilt), the congruence angle (assesses patellar lateralization) and the trochlear depth were made on Merchant's skyline views and on axial CTA on each of 50 symptomatic knees. Results are presented in graphic form with visual examples indicating a poor correlation between the two imaging methods. We conclude that skyline views are inaccurate and unsuitable primarily because they cannot be obtained in less than 30 degrees of flexion. We suggest that skyline views have no role to play in screening for maltracking as even florid examples must be missed, and would strongly urge that no surgery be performed on their basis alone as this would result in inappropriate operations. Although computed tomography is the preferred mode of assessing patello-femoral geometry, difficulties are still encountered and the ways of circumventing them are discussed.

Femur↗
PubMed1992

Gas-containing ganglia of the hip.

Three cases of ganglia related to the hip containing gas are presented. Gas may be shown by conventional radiography, linear tomography or computed tomography. All three cases had advanced degenerative disease of the joint. In degenerative disease, ganglia form through a pathway which allows the transfer of intra-articular gas into the ganglion. It is important to differentiate this phenomenon from overlying bowel gas and other causes of gas within soft tissues. It is the most specific radiological feature of ganglia around the hip.

Aged↗
PubMed1992

Intra-articular osteoid osteoma.

Osteoid osteomas located within the capsule of a joint are uncommon and present challenging diagnostic difficulties. Twelve patients with an intra-articular osteoid osteoma were studied retrospectively to determine the spectrum of clinical and radiological findings. The features differ significantly from the well known classical hallmarks of the extra-articular lesion. The symptoms are non-specific with pain similar to other common joint disorders and the response to salicylate less precise. On plain radiography intra-articular lesions are difficult to identify, lacking the florid periosteal new bone and intense perifocal sclerotic reaction. A detectable focal lesion is commonly absent with considerable delay between the onset of symptoms and radiological detection of the tumour nidus. Bone scintigraphy and computed tomography (CT) are essential for an accurate and early diagnosis. These imaging techniques reveal abnormalities in bone and cartilage growth, new bone formation and sclerosis distant from the tumour on either side of the joint, and disruption of the articular surface. Radiological follow up after surgery shows that these changes can be reversible, especially when the diagnosis is made early.

Adolescent↗
PubMed1992

Ilio-psoas bursa enlargement.

The clinical and radiological features of 14 patients with ilio-psoas bursal enlargement associated with articular disease of the hip are presented. The condition primarily affects patients over the range of 50 years with pre-existing hip disease, usually of long duration. A clinical diagnosis before investigation was never made in our series as the symptoms were non-specific and varied, consisting of pain (40%), a palpable groin mass (40%) and lower limb swelling (28%). The diagnosis can be made pre-operatively and the extent along the path of the ilio-psoas accurately delineated. The bursal contents, although predominantly fluid in nature, do include a varying proportion of solid components. Ultrasound is the simplest, quickest and most cost effective means of demonstrating the hip effusion, the bursa, its contents and extent. Although the compressive effects are well seen sonographically, computed tomography (CT) and magnetic resonance imaging (MRI) provide a better appreciation of the regional anatomy and hip joint disease.

Adult↗
PubMed1992

Bone mineral density in healthy normal women and reproducibility of measurements in spine and hip using dual-energy X-ray absorptiometry.

Bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA) has been measured in 394 healthy normal women. BMD is highest at the end of the 3rd decade and declines from 45 to 75 years by 0.0095 g/cm2/year in the lumbar spine and by 0.0052-0.0078 g/cm2/year in the upper femur depending on the site. BMD appears to increase in the 8th decade. Reproducibility (coefficient of variation (CV) of repeated measurements) was lowest in the lumbar spine (1.45%) and highest in Ward's triangle (4.29%). CV was not influenced by age at any site and by osteoporosis only in the femoral neck. BMD increased from L2 to L4 but the increase could not wholly be accounted for by the size of the vertebra, suggesting that the posterior elements were contributing to the observed increase of bone density.

Absorptiometry, Photon↗
PubMed1991

The role of ultrasound in the early diagnosis and management of heterotopic bone formation.

Heterotopic bone formation (HBF) is one of the many causes of painful limb swelling and is well recognized as posing clinical, radiological, and pathological diagnostic difficulties. We have evaluated the use of sonography to determine its role in reaching a diagnosis at a time when symptoms are maximal and the radiological diagnostic features absent. Serial ultrasound examination identified unique 'zone phenomea' in a heterogeneous group of eight patients before the classic radiological features appeared. The zone transformation matches the evolution and maturation process described pathologically and forms the basis of an early definitive diagnosis in all cases. The sonographic features are specific for the condition, unlike the scintigraphic appearances. Although CT confirms the peripheral location of the calcification, the low cost, safety, and general availability of ultrasound scanning make it the optimum imaging method for diagnosing and monitoring heterotopic bone formation.

Adult↗
PubMed1988

Provocation discography as a guide to planning operations on the spine.

In a prospective study we attempted to define the role of lumbar discography in the investigation of patients with low back pain with or without non-dermatomal pain in the lower limb. The records of 195 patients were studied at least two years after a technically successful operation. Of 137 patients in whom discography had revealed disc disease and provoked symptoms, 89% derived significant and sustained clinical benefit from operation. Of 25 patients whose discs showed morphological abnormality but had no provocation of symptoms on discography only 52% had clinical success. These findings support the continued use of lumbar discography for the investigation of this particular group of patients.

Adolescent↗
PubMed1987

99mTc-MDP retention in osteoporosis: relationship to other indices of bone cell activity and response to calcium and vitamin D therapy.

Serum calcium, albumin, phosphorus, and alkaline phosphatase, urinary creatinine and retention of 99mTc-methylene bisphosphonate (99mTc-MDP) were measured in 61 subjects with osteoporosis and the values compared with those obtained in normal subjects. 99mTc-MDP retention was inversely related with urinary creatinine output in normal subjects. In osteoporotic subjects urinary creatinine output was lower and 99mTc-MDP retention higher even when urinary creatinine output was taken into account. Other measurements were similar. In 21 subjects these measurements together with urinary hydroxyproline were performed before and after treatment with calcium and vitamin D. 99mTc-MDP and alkaline phosphatase fell; urinary hydroxyproline was unchanged. A single 24 h urine measurement after 99mTc-MDP injection is a valuable method of predicting whether calcium and vitamin D therapy will be useful in a particular case of osteoporosis.

Adult↗
PubMed1987

Disc damage above a spondylolisthesis.

Fifty-two patients with low back pain and spondylolisthesis at L5/S1 had discograms performed at the L4/L5 level. Retrolisthesis at L4/L5 occurred in 44%, but no direct relationship was demonstrated between the extent of retrolisthesis and either the grade of spondylolisthesis or the presence of disc damage. There was an inverse relationship between the degree of spondylolisthesis and L4/L5 disc damage. Thirty-six patients were assessed for symptomatic pain reproduction during discography. Fourteen (39%) had normal nuclear morphology and no pain induction on injection. Twenty-two patients had disc damage and 11 (50%) had symptomatic pain induced by injection. These results were correlated with the discographic appearances.

Adolescent↗