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Biomedical subjects

V R McCready

Publications and source records attributed to V R McCready.

At least 37 records · Page 2Linked to original sources
PubMed1997

99Tcm-MDP blood-pool phase in the assessment of repetitive strain injury.

We reviewed three-phase bone scans of the limbs of 7 patients suffering from limb pain suggestive of occupational repetitive strain injury (RSI) and compared them with 13 patients with limb pain due to various aetiologies. Doppler ultrasound measurement of blood flow had been performed in 13 of the 20 patients. The bone scan results showed increased blood flow and pooling (second phase) in the affected limbs of patients with RSI as compared to those with algodystrophy or non-specific limb pain (sensitivity 86%, specificity 85%). Doppler ultrasound also demonstrated increased blood flow to the affected limbs (sensitivity 83%) but failed to differentiate between the different aetiologies of pain (specificity 14%). We conclude that the blood-pool phase of three-phase bone scans can play a potential role in screening RSI patients.

Adolescent↗
PubMed1996

Thyroid cancer: a review of treatment and follow-up.

The importance of thyroid cancers far exceeds their frequency, since they are uncommon tumours accounting for only 1% of all malignancies and for even smaller proportion of cancer deaths (0.2%). A variety of distinct tumour types arise in the thyroid gland, with variable natural histories resulting from different rates of growth and biological aggressiveness. The long natural history of the majority of thyroid neoplasms imposes a commitment for long-term follow-up and stresses the importance of planning treatment so as to avoid delayed complications that impair the quality of life of patients. The management of thyroid cancer is multidisciplinary, requiring consultation and active intervention by surgeons, endocrinologists and radiotherapists. Surgery is of paramount importance in the successful eradication of the tumours while radioiodine offers a unique therapeutic approach. Treatment must be strongly influenced by consideration of prognostic variables.

Adenocarcinoma, Follicular↗
PubMed1996

Microbubble contrast agent for color Doppler US: effect on breast masses. Work in progress.

PURPOSE: To evaluate the effects of a new microbubble contrast agent for ultrasound (US) on breast masses. MATERIALS AND METHODS: Thirty-four patients underwent color Doppler US before and after intravenous injection of a "contrast agent" containing microbubbles. The authors subjectively evaluated the increase in intensity of the Doppler signals, the changes in the vascular patterns, and the timing of the transit of the microbubble bolus. The diagnostic confidence was assessed before and after administration of contrast material. RESULTS: After contrast material injection, there was greater and longer signal enhancement in the cancers than in the benign lesions. The cancers displayed characteristic vascular morphologic features, with more additional vessels visualized in relation to the lesion and a greater increase in vascular tortuousity. Shunts between vessels were demonstrated in all cancers but were not seen in any benign lesion. The diagnostic confidence increased with use of the contrast agent. The appearance at contrast-enhanced US led to a change in the US diagnosis in four patients. This increased both sensitivity and specificity to 100%. CONCLUSION: Injection of a microbubble agent enabled accurate differentiation of benign masses from carcinomas.

Adult↗
PubMed1996

Focal areas of increased renal tracer uptake on bone scans can mimic metastases in the lower ribs.

Focal renal concentration of radioactivity can simulate metastatic deposits in the lower ribs on bone scintigrams. 400 consecutive bone scintigrams were reviewed for focal areas of increased tracer activity in the kidneys. 62 patients (15.5%) had at least one renal hot spot. In 42 of these 62 patients (67.7%) there was an increased focal uptake in the left kidney (18 upper pole, 18 middle pole and six lower pole). 50 out of 62 bone scans (80.7%) showed increased activity in the right kidney (14 upper pole, 32 middle pole and four lower pole). With the incidence of focal areas of activity in the upper poles of the kidneys being 8%, the interpretation of a single focal abnormality projected over the lower ribs should be made with particular care, especially in cancer patients.

Adolescent↗
PubMed1995

Imaging metastatic testicular germ cell tumours with 18FDG positron emission tomography: prospects for detection and management.

The aim of this study was to investigate the role of positron emission tomography (PET) with [18F]fluoro-2-deoxyglucose (18FDG) in metastatic testicular germ cell tumours. Twenty-one patients with stage II-IV testicular germ cell tumours were imaged by PET with a multiwire proportional chamber PET system and 18FDG. Avid 18FDG uptake was seen in metastatic disease from primary seminoma and malignant teratoma. Normal tissue uptake was seen in differentiated teratoma or necrotic, fibrotic tissue. 18FDG standard uptake values and tumour to normal tissue ratios were 6.0 +/- 1.4 and 1.7 +/- 0.4 (mean +/- 1SD), respectively, for malignant tissue. Reduction of 18FDG tumour to normal tissue ratios from pre-treatment to on-treatment scans was predictive of response (n = 3). No significant reduction in 18FDG uptake was seen in patients not responding to therapy (n = 2). These results suggest a role for 18FDG PET in the detection and management of metastatic testicular germ cell tumours.

Abdominal Neoplasms↗
PubMed1995

Clinical significance of technetium-99m methylene diphosphonate myocardial uptake: association with carcinoma of the prostate.

Benign myocardial uptake of technetium-99m labelled phosphates, not related to cardiac or metabolic disorders, has been documented except in the case of 99mTc-methylene diphosphonate (MDP). The aim of this study was to assess the frequency of myocardial uptake and its possible association with malignant tumours in general and prostatic carcinoma in particular. We reviewed bone scintigrams performed with either 99mTc-hydroxydiphosphonate (HDP) or 99mTc-MDP over a period of more than 2 years for all patients with prostatic carcinoma and a matching group of patients suffering from other malignant and non-malignant disorders. A total of 965 scintigrams of 812 patients (males = 559, females = 253; age range 50-91 years, average age 69.2 years) were reviewed. Increased myocardial uptake was detected in 19 scintigrams (MDP = 13, HDP = 6) of 18 patients (17 males, one female). Most of the male patients with increased myocardial uptake had prostatic carcinoma (13/17) and were over 80 years of age (12/17). All patients were free of any cardiac or noncardiac disorder that might account for such uptake. When scintigraphy was repeated in the same patient, the uptake of 99mTc-HDP was more diffuse and of higher grade than that of 99mTc-MDP. "Benign" myocardial uptake of 99mTc-MDP is more common than previously thought. Although uptake of radiophosphates is attributed to asymptomatic atherosclerotic changes associated with old age, a strong association with prostatic carcinoma exists which may indicate variations in the bone: soft tissue affinity of different MDP complexes.

Aged↗
PubMed1995

Uptake of technetium-99m hexamethylpropylene amine oxime labelled white cells in lymph nodes involved in non-Hodgkin's lymphoma.

Radiolabelled white cell scanning is widely used to detect the presence of infection. We present a case of non-Hodgkin s lymphoma manifesting with signs and symptoms suggestive of infection, in which a technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) white cell scan demonstrated high uptake in lymph nodes involved by lymphoma. Differential cell analysis showed preferential lymphocyte labelling. The classification and management of the disease were changed accordingly. Our findings suggest that a future role for 99mTc-HMPAO labelled white cells in the assessment of disease activity of lymphoma should be investigated.

Diagnosis, Differential↗
PubMed1995

Colour DOPPLER image analysis for tissue vascularity and perfusion: a preliminary clinical evaluation.

An automated system for measuring features of colour Doppler (CD) images has been examined for its ability to measure tissue perfusion in vivo under conditions of diffuse vascularity. Seven statistical features were extracted from CD images of human calf muscle and compared with the arterial input measured by plethysmography. It was found that, when appropriate scanning procedures are employed, good correlation is achieved with arterial input (r = 0.96 to 0.99). Ultrasound beam angle was important, even for the assessment of "colour area." A sensitive velocity scale was ideal for "percentage colour" (r = 0.979). "Mean colour velocity" correlates well with arterial input (r = 0.979) when the volocity scale was optimised for each CD scan. "Integrated colour velocity per unit area" was more responsive when using a variable velocity scale (r = 0.99) than a fixed velocity scale (r = 0.98), but was less responsive to low flow. Automated CD analysis speeds up the process of quantitative assessment of tissue vasculature and perfusion. It is therefore essential for the analysis of dynamic studies of ultrasound contrast agents and serial examinations when monitoring response to therapy.

Arteries↗
PubMed1995

Detection of increased blood flow to the affected arm in repetitive strain injury with radionuclide and Doppler ultrasound studies. A case report.

A case of clinically diagnosed repetitive strain injury was referred for investigation to rule out the possibility of an occult bone disease. The patient was a female keyboard operator who had pain and tenderness over the flexor muscles of the right hand and arm. The pain was severe and almost constant. The authors observed an increase in Tc-99m MDP delivery to the affected forearm during the dynamic sequence of a three-phase bone scintigram, indicating increased blood flow compared to the contralateral side. The same result was achieved using quantitative blood flow measurements with the Doppler technique and Tc-99m HMPAO perfusion imaging. These findings agree with recent studies that suggest increased total arm blood flow in repetitive strain injury and may provide an easy screening method.

Adult↗
PubMed1994

Blood flow measurement in extremity soft tissue sarcoma with technetium-99m hexamethyl-propyleneamineoxime and single photon emission computed tomography.

Blood flow measurements were made in 28 patients with soft tissue sarcoma of the extremities to investigate the prognostic significance of tumour vascularity. Four patients with benign tumours also underwent blood flow measurement. Mean and maximum tumour blood flow was calculated from technetium-99m hexamethyl-propyleneamineoxime uptake measured using single photon emission computed tomography (SPECT), tumour volume measured from SPECT transaxial image reconstructions and cardiac output assessed with Doppler ultrasonography. Twenty-seven malignant lesions and one benign tumour showed increased uptake of isotope relative to surrounding tissues. Mean sarcoma blood flow varied between 1 and 33 ml per 100 ml tumour per min, and maximum flow between 5 and 57 ml per 100 ml per min. Fourteen patients developed progressive disease during the first year of follow-up. Eight of 11 patients with a high isotope uptake ratio, eight of 12 with a high mean blood flow and eight of 14 with a high maximum blood flow relative to the respective medians for the series showed disease progression.

Adult↗
PubMed1994

Dose-response study on thyrotoxic patients undergoing positron emission tomography and radioiodine therapy.

With the acknowledged problems associated with assessment of functioning thyroid mass and hence radiation dose, our policy had been to give 75 MBq iodine-131 at 6-monthly intervals to patients with Graves' disease until they became euthyroid. Since positron emission tomography (PET) has been available at this hospital, the radiation dose to the thyroid has been calculated with an accuracy of approximately 20%, the thyroid mass being determined from an iodine-124 PET scan. A dose-response study has been carried out on 65 patients who have received single or cumulative radiation doses of < 80 Gy. The results show that patients who receive a low radiation dose (< 20 Gy) at their first treatment have a high probability of remaining toxic at 12 months. In contrast, patients who receive higher radiation doses (> 40 Gy) at their first treatment have a high probability of control. The probability of becoming euthyroid increases more rapidly with increasing radiation dose than the probability of becoming hypothyroid. Following this dose-response study, a new treatment protocol has been introduced. A 124I PET tracer study prior to 131I therapy will be performed to enable a prescribed thyroid dose of 50 Gy to be delivered to patients with Graves' disease. Further 131I therapy will only be considered if patients are still toxic at 12 months.

Dose-Response Relationship, Radiation↗
PubMed1994

Reversible findings of methylene diphosphonate bone scintigraphy in Raynaud's phenomenon: case report and review of the literature.

A 53-year-old woman with carcinoma of the right breast, spinal metastases and right arm lymphoedema was referred for bone scintigraphy prior to commencement of chemotherapy. The patient arrived in the department complaining of pain in the left hand, which appeared red and slightly swollen. Bone scintigraphy revealed increased tracer uptake in the first four metacarpal and all the carpal bones of the left hand. A repeat three-phase bone scintigram, performed 1 week later when the patient was asymptomatic, showed equal blood flow to both hands with normal blood pool and uptake in bone images. The case demonstrates a state of reversibly increased bone uptake in a patient injected at the time of an episode of Raynaud's phenomenon and the possible implications for scan interpretation.

Bone Neoplasms↗
PubMed1993

Quantitative single-photon emission tomography for tumour blood flow measurement in bronchial carcinoma.

A single-photon emission tomography (SPET) technique for the absolute measurement of tumour perfusion is described. Phantom studies have shown that source-background ratios are dependent upon source size and radial position within the phantom. A means of correcting source-background count ratios for these variables has been developed and used to correct tumour-lung ratios obtained in 28 patients with bronchial carcinomas who underwent technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) SPET. On SPET images, the normal lung appears as a relatively homogeneous background. The relationship between 99mTc background concentration (kBq/ml) and counts/pixel was determined from phantom studies and the tumour 99mTc concentration from the background 99mTc concentration and corrected tumour-lung ratio. The total activity of the lipophilic 99mTc-HMPAO species injected was measured. The activity reaching the systemic circulation (Asys) was obtained by subtracting the activity trapped in the pulmonary circulation (obtained from background 99mTc concentration and lung volume). Tumour blood flow may then be calculated from fraction of Asys contained in the tumour provided cardiac output and extraction fraction are known. Blood flow through the central region of tumours ranged from zero to 59.0 (mean 14.1) ml min-1 100 g-1 and through the whole tumour from 0.6 to 68.0 (mean 20.6) ml min-1 100 g-1.

Blood Flow Velocity↗
PubMed1993

Radiation dose assessment in radioiodine therapy. Dose-response relationships in differentiated thyroid carcinoma using quantitative scanning and PET.

Dose-response charts have been constructed to determine the tumouricidal dose for differentiated thyroid carcinoma metastases and thus enable precise activities of radioiodine to be prescribed in order to maximise tumour kill and minimise morbidity. Tumour and normal residual thyroid absorbed doses from radioiodine-131 have been determined with increased precision using a dual-headed whole-body rectilinear scanner with special high-resolution low-sensitivity collimators. Improved accuracy in the estimation of functioning tumour mass has been achieved using positron emission tomography (PET) with a low-cost large area PET camera. Dose-response data have been obtained for 33 patients. Following near-total thyroidectomy and 3.0 GBq 131I, a mean absorbed dose of 410 Gy achieved complete ablation of thyroid remnants in 75% of patients. Patients who had persistent uptake in the thyroid region on subsequent radioiodine scanning had received a mean dose of only 83 Gy. Cumulative absorbed doses in excess of 100 Gy were found to eradicate cervical node metastases. Patients with bone metastases, who generally have a poor prognosis, were found to have received doses of the order of only 20 Gy to the tumour deposits. The dose-response data explain the spectrum of clinical responses to fixed activities of radioiodine. In future, they will enable precise prescription of radioiodine to achieve tumouricidal doses whilst avoiding the morbidity and expense of ineffective therapy.

Adenocarcinoma, Follicular↗