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Biomedical subjects

U Patel

Publications and source records attributed to U Patel.

124 records · Page 7Linked to original sources
PubMedDate not supplied

Dependence of apparent diffusion coefficients on axonal spacing, membrane permeability, and diffusion time in spinal cord white matter.

We used a numerical simulation of water self-diffusion among permeable cylinders to predict the dependence of MR-based apparent diffusion coefficients in white matter on axonal separation, barrier permeability, and diffusion time (T). The transverse apparent diffusion coefficient (tADC), calculated with simulated diffusion-sensitizing gradients perpendicular to the axon fibers, remains a function of T down to diffusion times as short as .1 microsec for a range of diffusion barrier permeability. As the diffusion time lengthens, the response of tADC depends on axon diameter, with decreases in tADC occurring earliest, and most dramatically, for the smallest fiber diameter simulated (2 microm). For a given axonal separation, asymptotic values of ADC are determined by permeability alone and are the same for 2-microm and 11-microm fibers of equal membrane permeability. The effect of increased relative intracellular volume is manifested primarily in a decrease in tADC at short T. Increases in interaxonal spacing increase the tADC at asymptotically long diffusion times and reduce the dependence on permeability. However, at the widest plausible axonal separations, permeability remains an important determinant of tADC. These simulations may enhance interpretation of measured tADC in the context of the underlying physiologic and structural changes at the cellular level that accompany white-matter disease.

Animals↗
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Complications of universal ureteral stent.

The universal stent is primarily a ureteral stent that also permits optional nephrostomy drainage. The complications associated with universal stent placement were analyzed with respect to the underlying pathology. The major complications included stent-induced ureteral stricture in 2 patients, and stent migration requiring emergency repositioning in 2 patients. Stent malfunction due to stent migration or occlusion, and bladder irritation were frequent also.

Adolescent↗
PubMedDate not supplied

Isolation of Aeromonas spp. from canal water.

Aeromonas sobria was identified from soil and canal water at the East End of London. There was a correlation between water and faecal isolates from children attending the nearby Children's Hospital. In view of the potential risk of enteric and non-enteric infections due to Aeromonas spp, efforts are needed to ensure that canals, rivers, natural water sources and domestic water supply are free of these organisms.

Aeromonas↗
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Iatrogenic arteriovenous fistula in a renal allograft: the result of a TAD guidewire injury.

A case is presented of an iatrogenic arteriovenous fistula developing in a renal allograft following guidewire manipulation during transplant renal artery angioplasty. Hyperdynamic flow through the fistula was causing a shunt of blood away from the renal cortex as demonstrated on sonography and scintigraphy. Selective embolization was performed, correcting the maldistribution of flow to the peripheral renal cortex. The diagnosis and difficulty in management of asymptomatic renal arteriovenous fistulae is also discussed.

Angiography↗
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Mesenteric desmoid of the appendix--a case report.

A case of an isolated mesenteric desmoid (fibroma) is presented with two unusual characteristics. First, it arises from the mesentery of the appendix. Second, it presents as a twisted desmoid. The CT and US characteristics are presented. This patient was without risk factors for mesenteric fibrosis such as Gardner's syndrome or previous surgery.

Appendiceal Neoplasms↗
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Emergency percutaneous nephrostomy: results and complications.

PURPOSE: Percutaneous nephrostomy is a well-established standardized procedure in the management of patients with various urologic problems. The goal of this study was to evaluate the effectiveness and safety of percutaneous nephrostomy in an emergency setting. PATIENTS AND METHODS: Emergency percutaneous nephrostomy was performed in 160 patients with ages ranging from 2 to 89 years (mean, 52 years). Access to the kidney was planned and achieved with C-arm fluoroscopic guidance. RESULTS: The initial technical success rate was 98%. Overall complication rate was 34%; 6% were major and 28% were minor. Major procedure-related complications, including sepsis, occurred in 6% of patients. Hematuria requiring transfusion was noted in 2.4% of patients. Minor complications included catheter displacement or malposition (4.8%), pelvic perforation (4.3%), paralytic ileus (2.4%), pneumonia/atelectasis (1.8%), and pleural effusion (1.2%). High-risk patients included those with diabetes, hypertension, and obesity. No deaths or significant morbidity resulted from any complication. CONCLUSIONS: Emergency percutaneous nephrostomy under fluoroscopic guidance is a simple, safe, and effective procedure and should be offered in all suitably equipped radiology departments.

Adolescent↗
PubMedDate not supplied

CT of infected bladder diverticulum.

A case in which pus within a bladder diverticulum simulated a deep pelvic abscess is presented. This pitfall in CT diagnosis should be considered in patients with bladder outlet obstruction with symptoms of infection.

Abscess↗
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Initial experience with helical CT and 3D reconstruction in therapeutic planning of cerebral AVMs: comparison with 3D time-of-flight MRA and digital subtraction angiography.

PURPOSE: We report our initial experience with helical CT and CT angiography (CTA) in evaluating cerebral arteriovenous malformations (AVMs) in comparison with time-of-flight MR angiography (MRA) and digital subtraction angiography (DSA). METHOD: Twelve AVMs were studied with CTA, non-gadolinium-enhanced MRA, and DSA. Reconstructed images were obtained in three display methods (maximum intensity projection, shaded surface black and white, shaded surface color). Shaded surface color display was obtained by assigning different colors to vessels and "presumed" nidus. The number of feeding arteries and draining veins associated with each AVM was independently counted in each modality. The relative ease of depicting the nidus and vessels was also determined in each display method. AVM nidus dimensions were measured on CTA and MRA source images and interobserver differences were compared. RESULTS: CTA-reconstructed images depicted more veins but fewer arteries than MRA. Shaded-surface color displays best delineated vessels and nidus. Nidus dimension measurement was possible on CTA in all AVMs but impossible on MRA in four AVMs due to interference by methemoglobin (three AVMs) and phase artifact (one AVM). The interobserver difference in nidus dimension as measured on CTA was significantly smaller than that on MRA. CONCLUSION: Reconstructed CTA images and CTA source images seem to be valuable adjuncts or alternatives to MRA.

Adolescent↗
PubMedDate not supplied

A prospective study of seroprevalence of Toxoplasmosis in general population, and in HIV/AIDS patients in Bombay, India.

Two hundred and seventy nine sera (age group 13-50 years) were tested for antitoxoplasma IgG/IgM antibodies by ELISA techniques; the diagnostic titer for positive test is 10 iu/ml or > 1:100. Sera were obtained from (i) 165 (100 men/65 women) healthy adult voluntary blood donors (HIV, HBsAg, VDRL negative); (ii) 89 consecutive HIV/AIDS patients (82 men/7 women); and (iii) 25 patients (HIV negative: 12 men/13 women) treated for cerebral Tuberculoma or Neurocysticercosis during this study from January 1996-June 1997. The overall seroprevalence was 30.9% (51/165) in the immunocompetent adult (group i) 34% (34/100) men and 26.2% (17/65) in women [range: 10-899 iu/ml; (mean: 376.8)]. In HIV infected hosts the seroprevalence [range: 21-340 iu/ml; (mean; 180)] was 67.8% (56/82 men, 04/07 women). The seroprevalence was 20.5% (8/39), 32.8% (22/67), 34.8% (16/46) and 38.4% (5/13) in the 2nd, 3rd, 4th and 5th decades respectively in healthy adults. In HIV/AIDS patients, 69% (29/42) in the 3rd and 70.6% (24/34) in 4th decade were seropositive. The risk of cerebral Toxoplasmosis (encephalitis-02, granuloma-24) was 43.3% (26/60, mean 250 iu/ml). The seroprevalence was 28% in group iii (range 12-80 iu/ml, mean 21 iu/ml). Anti-toxo IgM was negative in all. Primary Toxoplasma infection appears to be subclinical and prevalent throughout life. T. gondii has emerged as an important opportunistic infection in HIV/AIDS patients in Bombay. Recrudescence of cerebral toxoplasmosis (CTOX) is observed with low IgG response during mid-late stage of the disease, as seen in our patients (mean IgG 250 iu/ml, CD4+ = 283/cmm (range 43-504 in 5 patients). Primary prophylaxis for CTOX seems rationale and can be targeted to asymptomatic HIV/AIDS population at risk who are seropositive for T. gondii (mean IgG 111.5 iu/ml in our study). The very high predictive value of a negative test for TOX remains the best serological parameter for excluding acute episode of TOX.

AIDS-Related Opportunistic Infections↗
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Management of massive haemoptysis.

Massive haemoptysis is rare but associated with a high mortality. Even in a major regional cardiothoracic centre only one or two cases will be seen annually. As a consequence, no consensus about its investigation and management has emerged, with the result that much time may be lost on inappropriate investigation and treatment may be misdirected.

Acute Disease↗
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CT angiography in the evaluation of acute stroke.

PURPOSE: To determine the worth of CT angiography of the circle of Willis as a supplement to routine CT in the examination of patients with symptoms of acute stroke in terms of its depiction of the number and distribution of arterial stenoses or occlusions. We also sought to compare the accuracy of CT angiography with MR angiography and/or digital subtraction angiography (DSA). METHODS: One hundred forty-five patients with symptoms of acute stroke were examined with routine head CT and CT angiography of the circle of Willis. MR angiography was also performed in 27 patients and DSA in 28 patients. CT and MR angiograms and DSAs were reviewed for stenoses or occlusions involving the vessels about the circle of Willis. MR and CT angiograms were also evaluated for image quality, and the corresponding routine CT and MR studies were evaluated for the presence of arterial infarction. RESULTS: CT angiograms were rated good or excellent in 89% of cases whereas MR angiograms were rated good or excellent in 92% of cases. Arterial stenoses or occlusions were present on 43% of CT angiograms, 48% of MR angiograms, and 21% of DSAs. Findings were in agreement in 98% of the vessels analyzed by CT angiography and MR angiography. Similarly, there was overall agreement of findings in 99% of vessels analyzed by CT angiography and DSA. None of the patients had any immediate adverse reactions after administration of intravenous nonionic iodinated contrast material. CONCLUSION: CT angiography is an accurate and safe method for evaluating arterial stenoses or occlusions in the vessels about the circle of Willis. CT angiography should be used in patients with symptoms of acute stroke for whom evaluation of the intracranial vasculature is desirable.

Adult↗