Biomedical subjects

M Paley

Publications and source records attributed to M Paley.

At least 19 recordsLinked to original sources

PubMed2002

Diaphragm plication following phrenic nerve injury: a comparison of paediatric and adult patients.

BACKGROUND: A study was undertaken to evaluate whether adults differ from children in the indications and outcome of diaphragmatic plication following phrenic nerve injury. METHODS: A retrospective study was performed of 21 patients, 10 below the age of 5 and 11 older than 37 years. The indication for surgery for all the children was failure to wean from ventilatory support. The indications for surgery in the adult group were ventilator dependency (n=4) and symptomatic dyspnoea (n=7). All patients had at least one imaging study confirming diaphragmatic paralysis. The American Thoracic Society (ATS) dyspnoea scale, pulmonary function tests, and quantitative pulmonary perfusion scans were used as evaluation parameters. At surgery the diaphragm was centrally plicated. RESULTS: One child died immediately after surgery due to irreversible heart failure and two children died within 2 months of surgery from ongoing complications of their original condition. These three patients were considered as selection failures. Seven children were weaned from ventilatory support within a median of 4 days (range 2-140). Only one of four ventilated adults was successfully weaned. Seven adults who underwent surgery for chronic symptoms had a marked subjective improvement of 2-3 levels in the ATS dyspnoea scale. Pulmonary function studies in the seven symptomatic adults showed a 40% improvement above baseline. Severely asymmetrical perfusion scans reverted to a normal pattern after plication. CONCLUSIONS: Diaphragmatic plication offers a significant benefit to children with diaphragmatic paralysis and should be performed early to facilitate weaning from mechanical ventilation. While plication is of limited benefit in weaning ventilated adults, it results in significant subjective and objective lifetime improvement in non-ventilated symptomatic adults.

Adult↗

PubMed2001

Hyperthermic pleural perfusion with cisplatin: early clinical experience.

BACKGROUND: The preferred treatment for patients with pleural tumors or tumors with pleural extension has not been determined. Systemic and local modalities were studied, including intrapleural chemotherapy and hyperthermia, which mainly have been investigated separately. The objective of this study was to investigate the feasibility, toxicity and early results of a multimodality treatment consisting of surgery, chemotherapy, and hyperthermia in one session for the treatment of patients with pleural malignancies. METHODS: From November 1994 to September 1998, 26 patients (7 patients with mesothelioma, 11 patients with thymic neoplasms, and 8 patients with other tumors) underwent intraoperative hyperthermic pleural perfusion (HPP). Perfusion was performed with a roller pump and a heat exchanger. Cisplatin was added when the temperature stabilized to a mean of 40.8 degrees C (range, 40.2-41.5 degrees C). Dosages of cisplatin used were 60 mg in 2 patients, 100 mg in 2 patients, 120 mg in 1 patient, 150 mg in 18 patients, and 200 mg in 3 patients. The patients underwent the following associated surgeries: extended extrapleural pneumonectomy in 8 patients, resection of tumor without pleurectomy in 4 patients, resection of tumors with pleurectomy in 10 patients, and exploration and HPP only in 4 patients (thoracotomy in 2 patients and video-assisted thoracoscopy in 2 patients). RESULTS: There were no technical problems during the perfusion period. The systemic temperature rose to a maximum of 38 degrees C. There was no renal or hematologic toxicity, except in one patient who experienced thrombocytopenia. One patient died from complications related to a technical error. Eight patients had complications; the most bothersome were in four patients with empyema (early in two patients and late in two patients). The median postoperative hospital stay was 7 days (range, 2-50 days). Ten patients were alive 28-69 months after surgery. The overall 1-year, 2-year, and 3-year survival rates were 72%, 65%, and 44%, respectively. Complete ipsilateral pleuropulmonary control was achieved in 17 patients (9 patients who are alive and 8 patients who have died). CONCLUSIONS: Intraoperative HPP with cisplatin is feasible, easy to perform, and relatively safe. This method may offer excellent local control for patients with pleural tumors.

Adult↗

PubMed2001

Design and initial evaluation of a low-cost 3-Tesla research system for combined optical and functional MR imaging with interventional capability.

A 3-Tesla research system has been developed for functional and interventional magnetic resonance imaging (MRI) procedures on animal models based on a low field niche spectrometer. Use of two stages of fourth harmonic frequency multiplication has allowed us to produce a high-frequency spectrometer with good frequency stability based on a low-frequency direct digital synthesizer. The system has been designed with the ability to introduce interventional tools such as biopsy needles, radiofrequency (RF) electrodes, and fiber optics for optical spectroscopy and thermal ablation as well as drug infusions to allow function to be studied in the presence of external challenges. Full MR-compatible physiologic support capability allows animals to be maintained in a stable condition over extended periods of study. Functional MR images have been acquired by using gradient echoes (TR/TE = 40/12 msec) from the rat whisker barrel cortex using electrical stimulation (5-V, 1.5-mA, 1-msec pulses at 5 Hz via two needle electrodes inserted into the rat whisker pad). Initial results using respiratory gas challenges of 100% N(2), 100% O(2), and 10% CO(2) have shown excellent agreement between single wavelength (633 nm) optical and functional MR time series with subsecond time resolution. The 1-mm copper electrodes for interventional radiofrequency ablation procedures were easily visualized in the superior colliculus by using gradient echo sequences. This novel, low-cost, high field system appears to be a useful research tool for functional and interventional studies of rat brain and allows concurrent optical spectroscopy. J. Magn. Reson. Imaging 2001;13:87-92.

Animals↗

PubMed2001

Resection and perfusion thermochemotherapy: a new approach for the treatment of thymic malignancies with pleural spread.

BACKGROUND: Thymoma and thymic carcinoma with pleural spread have a high rate of locoregional recurrence and poor prognosis. Maximal debulking coupled with aggressive local treatment could offer a chance for cure. This study evaluates the early and midterm results of operation and hyperthermic pleural perfusion with cisplatinum for thymic malignancies. METHODS: Fifteen patients (11 men), 20 to 67 years old (10 thymoma, 4 thymic carcinoma, 1 carcinoma in thymic cyst) underwent resection and hyperthermic pleural perfusion between 1995 to 2000. All had pleural spread proven before or intraoperatively. Six of the thymoma cases were recurrent. Current operation included resection without pleurectomy (9 patients), resection with pleurectomy (5), and extrapleural pneumonectomy (1 patient) with intraoperative hyperthermic pleural perfusion in all. Intrapleural temperature reached 40.3 degrees C to 43 degrees C. The total dose of cisplatinum was 150 mg or more in 14 patients. RESULTS: Complete resection (R0) was achieved in 10 patients, subtotal (R1) in 3, and partial (R2) in 2. There was no operative mortality, no hemodynamic or respiratory disturbances during perfusion, and no hematologic, neurologic, or renal complications. Complications consisted of significant bleeding (2 patients), fever (2), and air leak (1 patient). Two patients with thymic carcinoma died after 27 and 34 months, and 1 is alive with no evidence of disease at 54 months. Two patients with thymoma died after 7 and 36 months. Eight are alive after 9 to 70 months. Four patients (all R0) are alive without local recurrence more than 60 months after operation and hyperthermic pleural perfusion. CONCLUSIONS: Operation and thermochemotherpy is feasible and safe in patients with thymic tumors. This method seems to offer excellent local control for patients with stage IV-a thymic malignancies. Midterm results suggest that operation plus hyperthermic pleural perfusion may lengthen survival in stage IV-a thymoma.

Adult↗

PubMed2000

Pseudo-random procedures for rapid presentation rates using optical imaging and spectroscopy.

Optical imaging of rat barrel cortex has provided detailed spatio-temporal maps of functional cortical architecture. We describe an event-related procedure (ERP) for optical imaging based on selective signal averaging as reported by Burock et al., using an anti-correlative pseudo-random event sequence. The sequence used 1 s vibrissal stimulation at 5 Hz, with an interevent interval of 2 s. This rapid presentation rate allows for greater statistical power per unit time, and allows for direct comparison of event-related studies with other imaging modalities. The spatio-temporal characteristics of single wavelength and spectrographic results were found to be comparable with those obtained by standard techniques, although a general lessening of haemodynamic response function (HRF) was noted. We also describe a method of locating barrel activity by spectral analysis of summed event data. Using this technique, the power spectrum of remitted light from the barrel region was found to peak within +/- 0.12 Hz of the inter-event interval frequency.

Algorithms↗

PubMed2000

Psammomatous melanotic schwannoma: presentation of a rare primary lung tumor.

A 30-year-old nonsmoking man underwent a left lower lobectomy with bronchoplasty for an obstructing lesion of the left lower lobe. Pathology results demonstrated a psammomatous melanotic schwannoma, a rare pigmented neural tumor of which only 25 cases have been reported as originating in the respiratory tract.

Adult↗

PubMed2000

Stable periodic vortex shedding studied using computational fluid dynamics, laser sheet flow visualization, and MR imaging.

Recirculating and detached flow patterns close to the carotid bifurcation are thought to play an important role in the development of carotid stenoses by promoting atherosclerosis. The aim of this study was to investigate a flow regime with strong transient characteristics, including vortex shedding and transport to develop methodologies appropriate to the analysis of carotid stenoses. The existence of a regular periodic vortex street behind a cylindrical flow obstruction was predicted and analysed in detail by Theodore van Karman in the early 20th century. This model was chosen in our study for both ease of phantom construction and of theoretical modelling using finite element computational fluid dynamics (CFD). The results of the theoretical calculations have been compared with two methods of flow visualization-laser sheet imaging and real-time echo planar magnitude MR imaging. Flow was investigated over a range of Reynold's number from 40 through 400 through which vortex shedding is predicted. Good overall agreement was obtained between the theoretical (16 mm-CFD) and experimental (16+/-2 mm-Laser, 17+/-2 mm-MRI) estimates of the Karman Vortex street wavelength for a Reynolds number of 200.

Carotid Arteries↗

PubMed1999

In vivo MRI measurements of bone quality in the calcaneus: a comparison with DXA and ultrasound.

Magnetic resonance imaging (MRI) has shown promise in the assessment of bone architecture. The precision and feasibility of MRI measurements in osteoporosis in vivo have been assessed in this study. T2' was calculated from measurements of T2 and T2* in the calcaneus of 32 postmenopausal women using a gradient-echo sequence PRIME (Partially Refocused Interleaved Multiple Echo). This sequence allows the measurement of T2 and T2* in one acquisition. In vivo measurements of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) were made in the calcaneus, spine and femoral neck. The ultrasound parameters broadband ultrasound attenuation (BUA) and speed of sound (SOS) were also measured in the calcaneus. These three techniques have not previously been compared in the same study population. The precision of the MRI technique was poor relative to the DXA and ultrasound techniques, with a CV of 6.9% +/- 4.4% for T2' and 5.5% +/- 3.6% for T2*. Approximately 4% of this is due to system error as determined by phantom measurements. The postmenopausal women were classified as having low BMD if they had a lumbar spine (L2-4) BMD of less than 0.96 g/cm2 (more than 2 standard deviations below normal peak bone mass). Calcaneal T2' was significantly correlated with calcaneal BMD (r = -0.79, p < 0.0001), BUA (r = -0.59, p = 0.0004) and SOS (r = -0.58, p = 0.0006). T2' was significantly different in postmenopausal women with normal BMD and those with low BMD (p < 0.01). However, the difference was of only borderline significance (p < 0.06) after adjustment for age and years since menopause.

Absorptiometry, Photon↗

PubMed1999

The assessment of postmortem brain volume; a comparison of stereological and planimetric methodologies.

We compared two methods of estimating the volume of 10 formalin-fixed brains using MRI. MRI was performed and total brain volume was then assessed using two distinct techniques: a stereological point-counting technique based on the Cavalieri principle, and an edge-tracing technique. The total brain volumes obtained using these two techniques were similar and correlated closely with each other (r = 0.97). Both methods could be optimised to a similar degree while maintaining the coefficient of error at an acceptably low level. However, the stereological assessment of brain volume required between 20 min and 30 min per brain, depending on the number of points per sampling grid, compared with 1 h per brain using the planimetric method. Thus, while planimetric and stereological approaches yield very similar results, the stereological method has the advantage of greater speed and, therefore, efficiency.

Aged↗

PubMed1999

R'2 measured in trabecular bone in vitro: relationship to trabecular separation.

Measurement of key parameters of the microstructure of trabecular bone is critical to the study of osteoporosis and bone strength. Density based methods cannot provide this information, and give only the total amount of bone present, and not its arrangement. Magnetic resonance imaging has shown the potential to provide information related to the microarchitecture of the trabecular bone matrix. Twelve samples (8 x 8 x 8 mm3 bone cubes) were cut from sheep vertebrae such that the trabeculae ran either parallel or perpendicular to each face. Detailed measurements of the structure of these bone cubes were made by histomorphometry, and compared to R'2 and R*2 measured with a spin and gradient-echo sequence, Partially Refocused Interleaved Multiple Echo, at 1.5 Tesla. The precision of the R'2 measurement (% coefficient of variation) was 8.7+/-5.1, and 7.7+/-4.3 for R*2. Uncorrected values of R'2 and R*2 were significantly correlated to density measured by quantitative computed tomography (r = 0.87, p = 0.0005, and r = 0.90, p = 0.0002, respectively), and trabecular bone area measured by histomorphometry (r = 0.80, p = 0.002, and r = 0.83, p = 0.0008, respectively). Density correction was effected by imaging the same slice of bone in two orientations (90 degrees and 0 degrees ) to the main magnetic field. For both R'2 and R*2 there was a significant difference between measurements in the 90 degrees and 0 degrees orientations (p < 0.01). The difference between the two values was used, and termed R'2net or R*2net. The net parameters were independent of bone mass. R'2net and R*2net were significantly correlated to trabecular separation (p < 0.05) with r = -0.58 and r = -0.62, respectively. These results demonstrate the ability of magnetic resonance imaging to characterize a key measure of the trabecular microstucture. An increase in trabecular separation has important biomechanical consequences in osteoporosis. This result also strengthens the hypothesis that the sensitivity of R'2 to osteoporosis-related bone changes is due to magnetic susceptibility effects in which rapid transitions between bone and marrow create local magnetic field inhomogeneities that result in an increase in R'2 values.

Absorptiometry, Photon↗

PubMed1999

[Plication of diaphragm for postoperative phrenic nerve injury in infants and young children].

Paralysis of the diaphragm may cause life-threatening respiratory distress in infants and young children because of paradoxical motion of the affected diaphragm and contralateral shift of the mediastinum during expiration. Phrenic nerve injury (PNI) may follow chest operations. 10 children with diaphragmatic paralysis and severe respiratory distress underwent plication of the diaphragm. Ages ranged from 14 days to 5 years. 9 had PNI after operations for congenital heart disease and 1 after resection of an intraspinal cervical lipoma. The right side was affected in 7, the left in 3. Indication for surgery was inability to wean from mechanical ventilation, which had ranged from 11 to 152 days (median 35). 8 underwent plication via a thoracic approach and 2 via an abdominal approach. There were no complications directly related to the operation. The interval from plication to weaning from mechanical ventilation ranged from 2 to 140 days (median 4). 1 patient died 2 hours after plication due to severe heart failure and 2 after prolonged hospitalization due to sepsis and multi-organ failure. 6 were extubated 2-8 days (median 4) after plication and 1 only after 40 days. Early diaphragmatic plication is simple and avoids more serious surgery. While effective in ventilator-dependent infants and young children, it should not be used in those with multi-organ failure. Early plication may prevent the complications of prolonged mechanical ventilation.

Child, Preschool↗

PubMed1998

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study.

OBJECTIVES: To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression. METHODS: The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics. RESULTS: This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background. CONCLUSIONS: Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychological assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

AIDS Dementia Complex↗

PubMed1997

High magnetic susceptibility coatings for visualisation of optical fibres on a specialised interventional MRI system.

The aim of this study was to develop methods of visualising optical fibres on MRI scans for monitoring interstitial laser therapy. Scans were performed on a specialised MRI extremity scanner at 0.17 T. Optical fibres of 0.4 mm diameter used for delivering laser energy were coated with iron particles from a superferromagnetic contrast agent. MR images of the fibres were acquired using gradient echo sequences (TR/TE = 300/10, 1 mm in-plane, 3 mm slice) and assessed for fibre visibility. Coated fibres could be resolved as lines 2 +/- 1 mm wide using the gradient echo sequence. Uncoated fibres were invisible on the sequences used for in vivo therapy monitoring due to partial volume averaging. It is concluded that optical fibre visualisation by MRI may be improved by coating with ferromagnetic particles. Biocompatibility requires further assessment, but direct coating appears to be a promising method for fibre visualisation in MR-guided laser therapy.

Contrast Media↗

PubMed1997

Exostosis of a rib causing laceration of the diaphragm: diagnosis and management.

A 17-year-old boy presented with spontaneous hemothorax due to a puncture wound of the diaphragm by an inward facing exostosis of the rib. Diagnosis was made by computed tomographic scan, and the patient underwent a video-assisted thoracoscopic procedure to remove the exostosis. This is only the eighth reported case of an exostosis causing hemothorax.

Adolescent↗

PubMed1997

Retroperitoneal collections--aetiology and radiological implications.

PURPOSE: Retroperitoneal collections related to the psoas, in the absence of pancreatitis, are uncommon. This study reviews the imaging, pathogenesis and management of retroperitoneal collections with particular emphasis on distinguishing imaging features and the role of percutaneous drainage. MATERIALS AND METHODS: Twenty-three retroperitoneal collections in 22 patients were reviewed in a 2-year period. Twenty-one patients underwent computed tomography (CT), with ultrasound (US) conducted in 14 and magnetic resonance imaging (MRI) in four. The clinical history and associated aetiological factors were noted. Methods of drainage were compared, pathological/microbiological results were recorded and the clinical outcome noted. RESULTS: The mean age of presentation was 46.9 years (range 18-85 years). There was a male to female preponderance (17 to 6). Eighteen collections proved to be abscesses with five haematomas confirmed. Of the abscesses, three were primary and 15 were secondary to spinal, gastrointestinal or renal disease. Escherichia coli was the commonest isolated organism followed by Mycobacterium tuberculosis. No haematomas were drained. Twelve abscesses were drained successfully by percutaneous methods; three were managed with antibiotics alone; three were managed surgically. CONCLUSION: Secondary abscesses predominate and investigation should be directed at excluding a gastrointestinal or renal source. Tuberculous disease remains a significant problem. Percutaneous drainage allows effective management, even in the presence of a secondary abscess.

Adult↗

PubMed1996

A multicenter proton magnetic resonance spectroscopy study of neurological complications of AIDS.

Human immunodeficiency virus (HIV) infection as seen in Europe and the United States has predominantly been contracted through male homosexual sex or intravenous drug abuse. In infected subjects, the brain is frequently affected both clinically and neuropathologically. The aim of this multicenter study has been to evaluate the value of single-voxel proton magnetic resonance spectroscopy (MRS) in the assessment of the neurological complications of acquired immunodeficiency syndrome (AIDS). MRS (voxel size = 8 ml, TR/TE = 1600/135 msec) was performed in 137 HIV-1-seropositive patients and 64 healthy controls without risk factors at three clinical MR sites operating at 1.5 T. The first result of this multicenter trial is that good reproducibility of results among participating sites was found. This demonstrates the reliability and robustness of MRS in the study of in vivo brain metabolism. In HIV patients, there was no significant correlation between metabolite ratios of brain detected by MRS and CDC grouping of patients or CD4 count. In contrast, the variations of brain metabolite ratios (NA/Cr, NA/Cho, and Cho/Cr) were related to the occurrence of encephalopathy, brain atrophy, or diffuse white matter lesions. There was no significant difference in brain metabolites between male homosexual AIDS patients and male intravenous drug user AIDS patients, whatever their neurological status (neurosymptomatic or neuroasymptomatic). Thus, the mode of transmission of HIV infection does not appear to affect the cerebral changes observed in the proton spectra from AIDS patients. Because of its ease of implementation and high information content, single-voxel proton MRS is likely to play a significant role in the evaluation of HIV-related encephalopathies.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Laser therapy for breast cancer: MR imaging and histopathologic correlation.

PURPOSE: To investigate magnetic resonance (MR) imaging guidance of interstitial laser photocoagulation to treat primary breast cancer. MATERIALS AND METHODS: Twenty female patients with symptomatic breast cancers diagnosed at cytologic examination underwent interstitial laser photocoagulation by means of a single fiber prior to surgical excision. Gadolinium-enhanced T1-weighted three-dimensional fast low-angle shot (FLASH) MR imaging was performed before and after laser therapy (median, 48 hours; range, 24-96 hours). Following resection, tumors were mapped in detail histopathologically. The extent of disease, size of laser burn, and extent of residual tumor were correlated with MR findings. RESULTS: Twenty-seven tumors were detected at histopathologic examination in the 20 patients. Five patients had more than one invasive mass. Twenty-five of the 27 tumors were identified as discrete enhancing masses at MR. The two missed invasive foci were obscured on MR images by diffuse patchy enhancement that correlated with the presence of an associated extensive intraductal component. Early (4-hour) follow-up images failed to depict the laser effect. Later (24-96 hours) follow-up images depicted the laser-induced necrosis as a zone of nonenhancement within the residual enhancing tumor. The correlation coefficients (MR vs histopathologic analysis) for the laser-burn diameter and residual tumor were 0.80 and 0.86, respectively. CONCLUSION: Delayed gadolinium-enhanced MR images can help define the extent of laser-induced necrosis and residual tumor after interstitial laser photocoagulation therapy in breast cancer.

Adult↗

PubMed1995

Spatial data analysis in the quantitative assessment of cerebral white matter pathology on MRI in HIV infection.

This study was carried out using MRI (proton density--and T2-weighted) on 16 HIV-negative controls, 9 symptom-free HIV-positive patients and 25 with CDC IV HIV disease. The studies from this last group had previously been allocated by a radiologist to the following categories: 8 with focal mass lesions and normal-appearing white matter; 9 with diffuse encephalopathy (high signal on T2-weighted images, affecting most or all of the white matter) and 8 with patchy encephalopathy (high signal affecting only one or two areas within the white matter). Moran's I, a statistic of spatial autocorrelation, was calculated for the grey-scale values of a sampled pixel array from a central white matter region of each of the images. All values of Moran's I calculated in this study showed a large positive excess over the expected value under randomisation, indicating highly significant positive auto-correlation in the spatial arrangement of the grey-scale values. On T2-weighted images a statistically significant increase in the mean value of Moran's I, compared with controls, was found in the diffuse encephalopathy group, indicating that quantifiable changes in the spatial autocorrelation of pixel data can be related to recognised qualitative changes in the appearance of white matter in subjects with HIV disease. A lesser, but significant, rise in the mean value of Moran's I was also found in the focal mass lesion group, suggesting that changes in spatial autocorrelation may indicate pathological change in advance of qualitative MRI changes.

AIDS Dementia Complex↗