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Biomedical subjects

A R Siddiqui

Publications and source records attributed to A R Siddiqui.

At least 19 recordsLinked to original sources
PubMed2003

Melanoma patients evaluated by four different positron emission tomography reconstruction techniques.

One hundred and nineteen patients with malignant melanoma were studied using 2-[ F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET). The images were reconstructed using ordered subset expectation maximization with and without attenuation correction and filtered backprojection with and without attenuation correction. The most probable draining lymph node chains were surgically explored and the tumour volume was quantified at histology. The four different reconstructions of the PET images were retrospectively graded on a five-point scale by two blind readers and compared with the tumour volume. The readers agreed within +/-1 grade 93% (529/568) of the time. Comparing the areas under the receiver operating characteristic (ROC) curves gave 0.698, 0.668, 0.694 and 0.684 for the four reconstruction techniques. The lowest value comparing any pair of the four reconstruction techniques was P=0.371. Thus, none of the reconstruction techniques gave significantly better results than any of the others. The sensitivity of detection was 85% for tumour volumes of 113 m or more (about 6 mm in diameter), but only 4% for tumours less than this size. It can be concluded that the use of attenuation correction gives aesthetically more pleasing images, but the sensitivity and specificity are not significantly improved.

Adult↗
PubMed2001

Hormone replacement therapy menopause with a better future--a survey of views on hormone replacement therapy (HRT).

OBJECTIVE: To assess the views and prescribing practices of doctors regarding hormone replacement therapy (HRT). METHODS: In April 1999, 103 doctors from a teaching hospital participated in a survey. Using a self-administered questionnaire, subjects were contacted at the departments of Internal Medicine, Family Medicine, Obstetrics and Gynaecology, and Orthopaedics. RESULTS: Seventy-two percent were below 40 years of age and 67% of the respondents were male. Most doctors believed that HRT decreases the risk of subsequent osteoporosis (97%), ischaemic heart disease (77%) and depression associated with menopause (64%). Doctors generally considered menopausal symptoms (90%), premature menopause (87%), surgical menopause (85%) and osteoporotic fracture (77%) as clear indications for hormone replacement therapy. Absolute contraindications to the therapy were stated as recent breast cancer (82%) and recent endometrial cancer (84%). Among the specialities covered, there were differing views on proposed duration of HRT. It was generally believed that a pelvic examination, cervical smear and mammography were pre-requisites when initiating and monitoring HRT. Majority (69%) felt that HRT should be offered to all menopausal women, assuming no contraindications and most (73%) did discuss HRT with their patients. However, less than 10% of the menopausal patients under their care were using HRT. Those doctors not in favor of universal offering of HRT (31%) considered unreliable patient follow up to be the main reason. Females were two times more likely to discuss HRT with their patients (p = .08). Doctors who discussed HRT with their patients were four times more likely to consider HRT for themselves or their spouses (p = .13). Gynecologists were eight times more likely to prescribe HRT than non-gynecologists (p = .001). CONCLUSION: Doctors are positively disposed to the universal offering, and use of HRT. Further studies are needed to understand a possible gap between perceived and actual prescribing practice.

Adult↗
PubMed2000

Paan without tobacco: an independent risk factor for oral cancer.

Oral cancer is the second most common cancer in women and the third most common in men in Pakistan. Tobacco is smoked and chewed extensively in Pakistan. Paan is a quid of piper betel leaf that contains areca nut, lime, condiment, sweeteners, and sometimes tobacco, which is also used extensively. We did this study to clarify the independent association of paan and oral cancer. Between July 1996 and March 1998, we recruited biopsy-proven, primary cases of oral squamous-cell carcinoma, from 3 tertiary teaching centers in Karachi, Pakistan, and controls pair-matched for age, gender, hospital and time of occurrence, excluding persons with a past or present history of any malignancy. There were 79 cases and 149 controls. Approximately 68% of the cases were men, 49 years old on average, the youngest being 22 years old and the eldest 80. People with oral submucous fibrosis were 19.1 times more likely to develop oral cancer than those without it, after adjusting for other risk factors. People using paan without tobacco were 9.9 times, those using paan with tobacco 8.4 times, more likely to develop oral cancer as compared with non-users, after adjustment for other covariates. This study identifies an independent effect of paan without tobacco in the causation of oral cancer. Its findings may be of significance in South Asian communities where paan is used, and among health-care providers who treat persons from South Asia.

Adolescent↗
PubMed2000

The value of good medical student teaching: increasing the number of radiology residency applicants.

RATIONALE AND OBJECTIVES: The authors attempted to define the value of good medical student teaching to the profession of radiology by examining the effect of radiology course improvements on the number of 4th-year students applying to radiology residencies. MATERIALS AND METHODS: Course evaluation and residency application data were obtained from six consecutive classes of 4th-year medical students at the study institution, and these data were compared with national data. RESULTS: Between 1995 and 2000, the number of 4th-year U.S. medical students applying to radiology increased 1.6 times. At the study institution, that number increased 4.5 times, a statistically significant difference (P = .020, chi2 test). Student survey data indicate that this increase reflects a general increase in the quality of radiology teaching in the study institution and specific changes in a required 2nd-year medical school course. CONCLUSION: These results strongly suggest that good medical student teaching pays important dividends, not only to the departments that provide it but also to the profession of radiology as a whole. Exposing students to good radiology teaching early in their medical school careers is especially important. Radiology departments that provide outstanding medical student education should be studied to help develop a model of educational best practices.

Chi-Square Distribution↗
PubMed1999

Clinical applications of technetium Tc 99m hexamethyl propylene amine oxime leukocyte scan in children with inflammatory bowel disease.

BACKGROUND: Labeled leukocyte imaging is a helpful diagnostic tool in the detection of inflammation and sepsis. The technetium Tc 99m hexamethyl propylene amine oxime (99mTc HMPAO)-labeled leukocyte scan has been found to be more sensitive than the Indium-111 labeled leukocyte scan in detecting inflammatory bowel disease, with reported sensitivities of 95% to 100%. Experience with the 99mTc HMPAO-labeled leukocyte scan was examined and its clinical applications evaluated in the immediate treatment of patients with inflammatory bowel disease. METHODS: A retrospective chart review was undertaken that included pediatric patients who underwent 99mTc HMPAO-labeled leukocyte scan at the James Whitcomb Riley Hospital for Children. The disease activity of patients with inflammatory bowel disease was assessed. The leukocyte scan was performed according to the manufacturer's specifications, and images were obtained 30 minutes and 2 hours after administration of the radiopharmaceutical. RESULTS: During the period of July 1996 through November 1997, 41 scans were performed in 35 patients. Twenty-nine patients had histologically proven inflammatory bowel disease: 24 with Crohn's disease, 4 with ulcerative colitis, and 1 with indeterminate colitis. Active inflammatory bowel disease was suspected in 24 patients when the leukocyte scan was performed. Twenty of the 24 patients (83% sensitivity) had abnormal findings in leukocyte scans that prompted more aggressive management in 15 (75%). Six of the 15 who were receiving maximum medical therapy underwent surgical resection of severely affected bowel segments, and medical treatment was intensified in the other 9. The remaining 5 patients were receiving optimal medical therapy, instituted at their recent visit, and did not require further medication adjustments. Four of the 24 patients with active inflammatory bowel disease had normal leukocyte scans (17% false-negative rate), 3 of whom were receiving corticosteroid therapy at the time the scans were performed. All of the 11 patients in whom inflammatory bowel disease was in remission and 6 patients who did not have inflammatory bowel disease had normal findings in leukocyte scans (100% specificity). CONCLUSIONS: Although a tissue diagnosis is still recommended, obtained during upper and lower gastrointestinal endoscopic examinations, and contrast radiography of the small bowel for the initial work-up of patients with suspected inflammatory bowel disease, the 99mTc HMPAO-labeled leukocyte scan is a safe and useful diagnostic adjunct for subsequent evaluation of patients known to have inflammatory bowel disease. The results of 99mTc HMPAO-labeled leukocyte scans directly influenced treatment of 75% of the study patients with active inflammatory bowel disease, which included the decision to refer patients for surgical intervention.

Adolescent↗
PubMed1998

High rates of discitis following surgery for prolapsed intervertebral discs at a hospital in Pakistan.

OBJECTIVES: To confirm the presence of an outbreak of postoperative infections following laminectomy and to determine the infection rate after interventions were instituted. DESIGN: Retrospective cohort study. Medical records were reviewed, personnel interviewed, and premises examined. SETTING: Surgical unit of hospital A in Pakistan. SUBJECTS: Patients who had surgical laminectomy between January 1993 and July 1994. INTERVENTION: Instructive program for nursing and medical staff in December 1993. RESULTS: From January to December 1993, 6 (15%) of 41 laminectomy patients developed postoperative discitis. The risk of discitis varied significantly by surgeon (P = .016); patients who had one particular surgeon, surgeon A, were nine times more likely to develop postoperative infections than patients who did not have surgeon A. Patients were not consistently cleaned or shaved before coming to the operating room, and personnel moved back and forth between the operation theater and other parts of the hospital without changing their gowns or slippers. After the instructional intervention, between January and July 1994, 2 (6%) of 31 laminectomy patients developed postoperative discitis, a rate not significantly lower than in the preceding 12 months (P = .45). Overall, from January 1993 through July 1994, female patients were more likely to develop discitis than males (31% vs 7%; relative risk, 4.4; 95% confidence interval, 1.3-15.6; P < .032). CONCLUSION: Endemic conditions require that laminectomy at hospital A be limited to those situations where the benefits of the surgery exceed the considerable risk of postoperative discitis.

Cohort Studies↗
PubMed1998

A short echo 1H spectroscopy and volumetric MRI study of the corpus striatum in patients with obsessive-compulsive disorder and comparison subjects.

OBJECTIVE: It is likely that the corpus striatum is involved in obsessive-compulsive disorder (OCD). Prior studies have inconsistently found alterations in caudate volumes in patients with OCD. This study was undertaken in the hope that N-acetylaspartate and volumetric measures together would elucidate the presence and nature of corpus striatum volumetric abnormalities in OCD. METHOD: Thirteen patients meeting the DSM-IV criteria for OCD, who had been medication free for a minimum of 6 weeks, and 13 psychiatrically normal matched comparison subjects participated in the study. Short echo 1H magnetic resonance spectroscopy (1H-MRS) was used to measure levels of N-acetylaspartate and several other cerebral metabolites from a 4.5-cm3 volume in the left corpus striatum of all 26 subjects. Metabolite levels were estimated by fitting the time domain spectroscopy data with a noninteractive computer program. Volumes of the left and right head of the caudate nucleus in each subject were determined by semiautomatic segmentation of the volumetric images. RESULTS: N-Acetylaspartate levels from the left corpus striatum were significantly lower in the patients with OCD than in the comparison subjects. There were no differences in either left or right caudate volume between the two groups. CONCLUSIONS: Despite the lack of differences in caudate volumes between the OCD patients and the comparison subjects, the lower level of N-acetylaspartate in the left corpus striatum of the patients suggests reduced neuronal density in this region. Inconsistent volumetric findings among prior studies may reflect a poorer sensitivity of magnetic resonance imaging morphometry for detecting neuronal loss compared with 1H-MRS measurement of N-acetylaspartate.

Adult↗
PubMed1997

Contamination of the pleural surfaces in childhood sarcoma. Use of colloidal P-32 to reduce radiation dose to the whole lung.

Children with pulmonary sarcomas who have diffuse contamination of the pleural cavity present a difficult management problem for the radiation oncologist. Doses required to control even microscopic disease exceed lung tolerance. We report on the use of intracavity colloid P-32 in an attempt to treat the pleural surface and spare normal lung parenchyma and tissues of the chest wall. Three children--18 months, 12 years, and 3 years of age--had spillage of pulmonary sarcomas into the chest cavity. All children were treated with systemic chemotherapy. Initially, 0.5 mCi of technetium sulfur colloid (99mTc-sulfur colloid) was instilled into the pleural space to ascertain even distribution of isotope. This was then followed by installation of 5.0 mCi of colloidal P-32. Uniform distribution was then confirmed by bremsstrahlung scanning. All three patients are in complete remission 3.5 years, 3 years, and 1 year after treatment, respectively. The major toxicity was asymptomatic pleural thickening, which could be confused with disease. This was confirmed histologically to be fibrous in the first patient. The process diminished or stabilized with time in all 3 patients over the period of observation. In this small series, intrapleural colloidal P-32 appeared to be safe and well tolerated and would be expected to be less toxic than wide-field external beam in the treatment of spilled pulmonary sarcomas.

Child↗
PubMed1997

Imaging modalities in pediatric oncology.

Many imaging modalities are available for the diagnosis, follow-up, and sometimes treatment of pediatric oncology diseases. The advantages and disadvantages, indications and contraindications, techniques, and patient preparations of the most commonly used modalities are discussed in this article. The role of sedation and the most widely used drugs are also discussed.

Child↗
PubMed1996

Visual presentation of the staging of pediatric solid tumors.

Staging systems are used in staging most pediatric solid tumors outside the central nervous system. Common solid, nonneurologic pediatric tumors include liver tumors, Hodgkin disease, non-Hodgkin lymphoma, Wilms tumor, rhabdomyosarcoma, neuroblastoma, Ewing sarcoma, and osteosarcoma. Traditional staging of pediatric tumors depends on the anatomic distribution of the malignant disease. Almost all staging systems are based on the spread of the local primary tumor, metastasis to regional lymph nodes, and distant blood-borne metastatic spread. There is some variability as to how tumor spread is assessed. Such assessment may be performed before or after surgery. There are many potential problems with tumor staging systems. The systems vary in complexity and clinical usefulness, and there is some variation in the criteria used in the different systems. It is important for radiologists to have a sound working knowledge of staging systems to facilitate accurate staging. Imaging is an important aspect of every staging system.

Bone Neoplasms↗
PubMed1995

Hürthle cell carcinoma in an autonomous thyroid nodule in an adolescent.

A 16-year-old girl presented with a palpable thyroid nodule which was found to be functioning autonomously by radioiodine (123I) scintigraphy. After needle biopsy proved non-diagnostic, surgical excision showed the nodule to be Hürthle cell carcinoma. Functional thyroid nodules are rarely malignant, thyroid carcinoma is rare in childhood, and Hürthle cell carcinoma is a rare thyroid neoplasm, so the presence of these three rare conditions in one patient makes it a very unusual case.

Adenocarcinoma↗
PubMed1994

Osteomyelitis and pyogenic infection of the sacroiliac joint. MRI findings and review.

Acute pyogenic sacroiliac joint infection and osteomyelitis of adjacent bones often present with severe, poorly localized lower back, pelvic or hip pain. Five cases of sacroiliac joint infection or sacroiliac bone osteomyelitis were evaluated by MRI. MRI may be a helpful diagnostic tool to evaluate early changes of infection in the sacroiliac area. It is very sensitive for detecting bone marrow abnormalities; however, it is non-specific and can not accurately differentiate osteomyelitis from sacroiliitis.

Arthritis, Infectious↗
PubMed1993

Prospective study of magnetic resonance imaging and SPECT bone scans in renal allograft recipients: evidence for a self-limited subclinical abnormality of the hip.

We recently reported that typical abnormalities of avascular necrosis (AVN) in magnetic resonance images (MRI) of the hips of asymptomatic renal transplant recipients whose plain radiographs are normal may improve spontaneously and even disappear completely. We present the results of serial bone scans, most of which were performed with single-photon emission computed tomography obtained over periods as long as 24 mo after transplantation in 72 of these patients. Three paired imaging studies (i.e., MR and bone scan performed within 30 days of each other) were available for each of these patients. In three patients, both the MR images and the bone scans showed changes consistent with bilateral AVN within 4 mo after transplantation. All three patients developed hip pain which was bilateral in two and unilateral in one. Two patients (three hips) required surgical intervention at which time AVN was found on pathologic examination of all three hips. None of the remaining 69 patients developed hip pain during the study. However, in nine patients whose MR studies were consistently normal, at least one bone scan was abnormal (13 hips). The presence of AVN was pathologically confirmed in each of the hips subjected to surgery. Where the imaging findings were identical to those in the asymptomatic patients as well as those in whom the imaging abnormality regressed, we suggest that the subclinical imaging abnormalities represent mild AVN, which is reversible in some cases. Since the process was identified in 10 hips by MRI and in 13 hips by bone scan, both studies are needed to detect subclinical AVN. This may be important if treatment of subclinical disease is clearly shown to prevent progression to symptomatic AVN.

Adolescent↗
PubMed1992

Isotope studies in children: an update.

Hepatobiliary scintigraphy is an accurate, simple, and relatively noninvasive method for the diagnosis of biliary atresia, a condition in which early diagnosis is of paramount importance. Radionuclide gastrointestinal transit studies are useful in devising the surgical approach in children with suspected gastroesophageal reflux. Renal scintigraphy in the newborn period is used to decide the need for surgical intervention in a hydronephrotic kidney. Relatively new radiopharmaceuticals such as metaiodobenzyleguanidine, thallium, and deoxyglucose are useful in detecting tumors and in predicting the viability.

Child↗
PubMed1992

Single photon imaging computed tomography (SPECT) for localization of epileptogenic focus in patients with intractable complex partial seizures.

Interictal and ictal HIPDM-SPECT brain scans were obtained in 38 patients who eventually underwent temporal lobectomy for treatment of medically intractable complex partial seizures (CPS). Interictal studies revealed decreased regional cerebral perfusion (rCP) in the temporal lobe corresponding to the eventual site of surgery in 76% of the patients. Similarly, ictal studies demonstrated increased rCP in 91% of the patients. Of the 33 patients who had both interictal and ictal SPECT studies, 23 (70%) showed increased rCP in the ictal state and decreased rCP in the interictal state in the same temporal lobe which was subsequently removed. The SPECT scans were particularly helpful in providing confirmatory evidence for localization and in deciding to undertake temporal lobectomy in 16 patients whose EEG studies had provided less secure localization. Our experience suggests that interictal and ictal SPECT brain imaging can be easily obtained and provides reliable localizing information in the epileptic patients being considered for temporal lobectomy.

Adolescent↗
PubMed1990

Detection of rejection in renal allografts. Evaluation with duplex sonography and DTPA renal scintigraphy with kidney/aorta perfusion ratios.

Duplex sonography and technetium-99m DTPA renal scintigraphy have been used to distinguish acute rejection from other forms of renal allograft dysfunction. In this study, duplex sonography and renal scintigraphy were compared as methods to detect rejection. Eighty-four episodes of renal allograft dysfunction that had concurrent duplex sonography and renal scintigraphy over a 17-month period were reviewed. During the duplex sonography examinations the resistive index (RI) was measured from the renal cortex. Scintigrams were evaluated for allograft perfusion and function. The kidney to aorta (K/A) ratio was calculated from the upstroke of the perfusion curve. All diagnoses were established by clinical criteria. Histologic proof was available in 49 cases. There were two episodes of hyperacute rejection, 30 episodes of acute rejection, 14 episodes of chronic rejection, and 38 episodes of dysfunction without rejection. Using an RI greater than or equal to 0.70, the sensitivity and specificity for detecting acute rejection were 90% and 76%, respectively, compared with 37% and 76% for renal scintigraphy. The K/A ratio was not helpful in the diagnosis of rejection.

Aorta↗
PubMed1990

HIPDM-SPECT brain imaging in the presurgical evaluation of patients with intractable seizures.

We report the results of interictal and ictal HIPDM-SPECT brain imaging in 34 patients who eventually underwent temporal lobectomy for treatment of medically intractable complex partial seizures. Interictal studies revealed decreased regional cerebral perfusion (rCP) in the temporal lobe corresponding to the eventual site of surgery in 73% of the patients. Similarly, ictal study demonstrated increased rCP in 93% of the patients. In 69% of the patients, the SPECT studies were able to demonstrate both increased rCP on the ictal scan and decreased rCP on the interictal scan in the same location, corresponding to the eventual site of surgery. These results suggest that interictal and ictal SPECT brain imaging can be easily obtained and provide reliable localizing information in the presurgical evaluation of patients with medically intractable epilepsy.

Adolescent↗