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A Alavi

Publications and source records attributed to A Alavi.

At least 235 records · Page 13Linked to original sources
PubMed1991

Antifibrin scintigraphy in the diagnostic evaluation of acute deep venous thrombosis.

Antifibrin scintigraphy is a new and innovative approach to the diagnosis of acute deep venous thrombosis (DVT). Many antifibrin monoclonal antibodies (Mo-Abs) have been described, but only two, 59D8 and T2G1s, have undergone broad preclinical or clinical investigation. Both of these MoAbs recognize an epitope on the amino terminal end of fibrin. The epitope for 59D8 and T2G1s is available for binding only on newly formed, acute thrombi. Preclinical studies have confirmed the specificity of these MoAbs for acute DVT, and have demonstrated their ability to image experimentally induced DVT. Preliminary clinical studies in patients with signs or symptoms of DVT have evaluated indium-111 59D8 Fab and technetium-99m T2G1s Fab'. Fragments of the intact MoAbs are employed to promote faster blood clearance and to reduce immunogenicity. The initial clinical studies indicate that antifibrin scintigraphy has a diagnostic accuracy approaching 90%. Antifibrin scintigraphy has the potential for overcoming many of the deficiencies of both invasive (contrast venography) and noninvasive (Doppler/ultrasound, impedance plethysmography) methods for detecting DVT. With a single procedure, it provides an accurate and rapid evaluation of both lower extremities, both above and below the knee. Because of its unique specificity for acute DVT, it should have excellent potential for use in patients with suspected acute, recurrent DVT, a condition difficult to diagnose by all currently employed tests for DVT.

Animals↗
PubMed1991

A noninvasive strategy for the management of patients suspected of pulmonary embolism.

As a consequence of recent studies that have (1) established the role for ventilation-perfusion lung scanning in the diagnosis of pulmonary embolism, (2) clarified the contribution of clinical assessment to the diagnostic utility of lung scans, and (3) established a role for the noninvasive assessment of the lower extremities for deep venous thrombosis in patients suspected of having pulmonary embolism, we can now manage clinically stable patients suspected of pulmonary embolism without need for invasive diagnostic procedures. The various studies establishing this approach are reviewed, and an algorithm is presented that allows for the noninvasive workup of clinically stable patients suspected of having pulmonary embolism.

Algorithms↗
PubMed1991

An evaluation of preoperative and postoperative ventilation and perfusion lung scintigraphy in the screening for pulmonary embolism after elective orthopedic surgery.

One hundred two patients undergoing elective knee or hip arthroplasty were studied with radionuclide ventilation scans (V) and perfusion scans (Q) preoperatively (preop) and postoperatively (postop) to assess their relative value in the diagnosis of asymptomatic pulmonary embolism (PE) after orthopedic surgery. Postop Q were read in combination with preop V and Q and postop V using prospective investigation of pulmonary embolism diagnosis (PIOPED) criteria. Of 25 postop Q interpreted as either high or intermediate probability for PE, preop Q were judged useful in 96%; the postop V were useful in 78%; and the preop V were not helpful in any of the cases. Of 63 postop Q interpreted as low probability, preop Q were useful in 74%; the postop V were useful in only 33%; and the preop V were useful in only one case. When postop Q were read as normal (14 cases), none of the three auxiliary studies were found to be useful. Overall, postop V were more helpful than preop Q in only 2%, and preop V contributed significantly in only 1%. This experience suggests that preop Q alone is the most useful adjunct to the postop Q in the postoperative evaluation for PE. The authors conclude that to screen for asymptomatic PE after elective orthopedic surgery, preop Q should be performed in all cases, preop V are not necessary, and postop V need be performed only if a baseline preop Q is not available.

Aged↗
PubMed1991

Cold defects in in-111 labeled leukocyte imaging of osteomyelitis in the axial skeleton.

Use of In-111 oxine labeled leukocytes in the detection of osteomyelitis of the peripheral skeleton usually presents few problems. However, the diagnosis of osteomyelitis is more difficult in marrow-bearing areas because uptake of indium is normal. Sixty-one In-111 labeled leukocyte scans, that had been performed to exclude osteomyelitis of the axial skeleton, pelvis, and proximal long bones, were reviewed. Eight cold defects were identified at sites of suspected osteomyelitis. Five of these were surgically proven osteomyelitis. Nineteen percent of all cases of osteomyelitis in these areas (5 of 26) presented as cold defects. This incidence of osteomyelitis presenting as cold defects is higher than previously reported. Therefore, the possibility of osteomyelitis should be strongly considered when a cold defect is identified in red marrow areas.

Humans↗
PubMed1991

Analysis of brain and cerebrospinal fluid volumes with MR imaging. Part I. Methods, reliability, and validation.

A computerized system was developed to process standard spin-echo magnetic resonance (MR) imaging data for estimation of brain parenchyma and cerebrospinal fluid (CSF) volumes. In phantom experiments, the estimated volumes corresponded closely to the true volumes (r = .998), with a mean error less than 1.0 cm3 (for phantom volumes ranging from 5 to 35 cm3), with excellent intra- and interobserver reliability. In a clinical validation study with actual brain images of 10 human subjects, the average coefficient of variation between observers for the measurement of absolute brain and CSF volumes was 1.2% and 6.4%, respectively. The intraclass correlations for three expert operators is greater than .99 in the measurement of brain and ventricular volumes and greater than .94 for total CSF volume. Therefore, the authors believe that their technique to analyze MR images of the brain performed with acceptable levels of accuracy and reliability and that it can be used to measure brain and CSF volumes for clinical research. This technique could be helpful in the correlation of neuroanatomic measurements to behavioral and physiologic parameters in neuropsychiatric disorders.

Algorithms↗
PubMed1991

Analysis of brain and cerebrospinal fluid volumes with MR imaging: impact on PET data correction for atrophy. Part II. Aging and Alzheimer dementia.

A new, computerized segmentation technique, in which magnetic resonance (MR) imaging produces accurate volumetric measurements of brain and cerebrospinal fluid (CSF) without the limitations of computed tomography, was used in a retrospective analysis of digitized T2-weighted MR images of 16 healthy elderly control subjects and 16 patients with Alzheimer dementia. Ventricular and extraventricular CSF was quantified, and the effects of aging were studied; in both groups, the atrophy measurement was used to correct metabolic values obtained with positron emission tomography. Patients with Alzheimer dementia had higher total CSF; extraventricular, total ventricular, and third ventricular CSF volumes (49%, 37%, 99%, and 74%, respectively); and 7% lower brain volumes than the control group. The patients also showed a more marked decline in brain volumes and a greater increase in CSF volumes with advancing age than the control group. They had a 25.0% increase in corrected whole-brain metabolic rates; the control group had only a 15.8% increase. The use of this technique may provide a basis for further studies of aging and dementia, including regional volume analysis.

Aged↗
PubMed1991

Registration of three-dimensional MR and PET images of the human brain without markers.

Axial and sagittal magnetic resonance (MR) sections and contiguous sections of axial positron emission tomographic (PET) images obtained with fludeoxyglucose F-18 were used to evaluate a new method of registering three-dimensional images of the brain. The users specified the interhemispheric fissure plane in three dimensions for both the MR and PET data sets by specifying its endpoints within several axial sections. A transformation matrix aligning the interhemispheric fissure plane in MR and PET space was calculated and used to create one resectioned PET image on the resectioned PET image, and the user specified the remaining translations and rotation by moving the overlaid outline of the MR image. MR and PET data sets in four subjects were registered. The three-dimensional error on average was less than 3.8 mm and never exceeded 7.5 mm. Less than 1 hour per patient was required for registration. The method is accurate unless the interhemispheric fissure deviates significantly from a planar configuration. It does not need thin or contiguous MR sections and provides an estimate of the total registration error for every case.

Brain↗
PubMed1991

Diagnostic imaging of musculoskeletal infection. Roentgenography; gallium, indium-labeled white blood cell, gammaglobulin, bone scintigraphy; and MRI.

A great deal of effort has been made to evaluate and define the role of various diagnostic imaging techniques in various clinical settings that complicate the diagnosis of osteomyelitis. Except possibly in neonates, bone scintigraphy remains generally recommended when there has been no previous osseous involvement. In other cases of chronic disease, previous fracture or trauma, prosthesis, and diabetic foot, In-WBC scintigraphy is generally accepted as an appropriate imaging technique. MRI will play an increasingly important role in diagnosing osteomyelitis and may prove to be an important adjunct in these cases. Research continues to improve our current diagnostic armamentarium. In-IgG appears to avoid practical deficiencies encountered with 67Ga and In-WBC; it remains to be seen what role this agent will play in routine clinical practice. All agents to date image inflammation, not infection, and most require delayed imaging sessions, usually at 24 hours. These shortcomings necessitate further research to develop new radiotracers that can provide useful images within several hours and that are specific for infection, perhaps ultimately delineating the particular microorganism involved.

Adult↗
PubMed1991

Diagnosis and management of the infected total joint arthroplasty.

The preoperative diagnosis of the infected orthopedic implant is complicated by lack of a single precise test to forewarn patient and surgeon of the presence of microorganisms. Given the overall limitation of accuracy of preoperative diagnosis to approximately 80% when 111In scanning, preoperative aspiration, and ESR are considered, it would seem prudent to approach each revision surgery with the possibility in mind of subclinical sepsis as the cause for failure of the implant. The essentials of surgical technique including thorough debridement of the wound and removal of all existing foreign bodies, especially including PMMA bone cement, are critical to minimizing the risk for occurrence or persistence of sepsis. Although the use of antibiotic impregnated bone cement may enhance the treatment of orthopedic sepsis, the data available to date lead to the conclusion that two-stage revision surgery in the face of known sepsis remains the cornerstone of surgical therapy for the infected implant, along with aggressive and rational antibiotic treatment. The surgeon is offered the following guidelines in the management of the septic total hip arthroplasty. 1. Preoperative evaluation including ESR, 111In WBC scan, and aspiration for culture and sensitivity (fluoroscopically guided for the hip) will produce on average approximately 80% accuracy. 2. Intraoperative cultures at the time of revision surgery should be obtained prior to administration of systemic antibiotics; three tissue specimens (hip capsule, femoral membrane, acetabular membrane) should be submitted for culture and sensitivity determination. 3. Careful debridement of the surgical site of granulation tissue and all foreign bodies (e.g., PMMA) should be performed within the limits of patient safety to maximize the likelihood of success.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Infectious imaging with indium-111-labeled nonspecific polyclonal human immunoglobulin.

Nonspecific polyclonal immunoglobulin (IgG), prepared from pooled human serum gamma globulin and labeled with 111In has been reported to be equivalent to antigen-specific antibody in the detection of focal infection or inflammation during the first 24 hr after injection. We describe our experience in a Phase II clinical study using 111In-IgG in 15 patients (8 males, 7 females) ranging from 26 to 80 (mean = 50) yr of age with suspected focal infection/inflammation. Pathologic confirmation was obtained in 5/15 cases. A combination of clinical course, laboratory results, and other imaging procedures were used to categorize the other 10 patients. One possible false-negative involved a presumed aspiration pneumonia in a patient with a history of aspiration, bibasilar infiltrates on chest film, and no other identified source of infection. Otherwise, there were 10 confirmed positives, 4 confirmed negatives, and no false-positives. Our findings confirm earlier reports that 111In-IgG may be a superior imaging agent for infection/inflammation with practical advantages over 67Ga-citrate and 111In-labeled leukocytes.

Drug Evaluation↗
PubMed1991

Bronchobiliary fistula detected by cholescintigraphy.

We present a case of a bronchobiliary fistula initially detected by hepatobiliary scintigraphy. The patient developed bilioptysis 18 mo after undergoing a right hepatic lobectomy and resection of the common bile duct for cholangiocarcinoma. The procedure was complicated by the development of a subphrenic abscess that required percutaneous biliary drainage.

Adult↗