Biomedical subjects

Muhammad Babar Imran

Publications and source records attributed to Muhammad Babar Imran.

6 recordsLinked to original sources

PubMed2006

Gated spect myocardial perfusion scintigraphy for identifying septal perfusion artifacts in left bundle branch block.

OBJECTIVE: To determine the role of gated Single Photon Emission Computed Tomography (SPECT) for accurate assessment of myocardial perfusion scintigraphy (MPS) of patients with left bundle branch block (LBBB). DESIGN: Analytical study. PLACE AND DURATION OF STUDY: Punjab Institute of Nuclear Medicine (PINUM), Faisalabad, Pakistan, from June 2002 to April 2003. PATIENTS AND METHODS: MPS data of patients with LBBB was analyzed. Resting gated SPECT MPS was performed after an injection of 740 MBq 99mTc-MIBI in 10 normal and 25 subjects with LBBB (with low probability of coronary artery disease). Visual and quantitative analyses were done on non-gated (NG), end diastolic (ED), end systolic (ES) images. Calculations included septal to lateral wall ratio (SLR), myocardial thickening (MT=% increase in counts during systole) at end systolic phase and myocardial thickening at peak level (% peak MT). RESULTS: Septal hypoperfusion was noted in 19 (76%) patients on NG images and in only 1 (4%) patient on gated SPECT ED images. On NG images of LBBB group, SLR was lower than in controls (0.68+/-0.07 vs. 0.87+/-0.05, p<0.001). SLR of LBBB patients approached to that of control group in gated SPECT ED data (0.86+/-0.06 vs 0.88+/-0.06, p=ns). Myocardial thickening at ES for septum was markedly lower in LBBB group than in controls (21.83%+/-10.86 vs. 66.32%+/-20.15, p<0.001). CONCLUSION: In patients with LBBB, reduced septal thickening results in artifactual septal perfusion defects. Gating the perfusion scintigraphy and reporting perfusion status on end diastolic frames in LBBB patients can eliminate these artifacts.

Adult↗

PubMed2005

Antimicrobial peptide 99mTc-ubiquicidin 29-41 as human infection-imaging agent: clinical trial.

UNLABELLED: Ubiquicidin (UBI) 29-41 is a cationic, synthetic antimicrobial peptide fragment that binds preferentially with the anionic microbial cell membrane at the site of infection. The current study was conducted to evaluate its potential as an infection-imaging agent in humans. METHODS: Eighteen patients, 9 female and 9 male (mean age, 31.7 y; range, 5-75 y), with suspected bone, soft-tissue, or prosthesis infections were included in the study. (99m)Tc-UBI 29-41 in a dose of 400 microg/370-400 MBq was injected intravenously in adults. A dynamic study was followed by spot views of the suspected region of infection (target) and a corresponding normal area (nontarget) at 30, 60, 120, and 240 min. The target-to-nontarget ratios were used to find the optimum time for imaging. Whole-body anterior and posterior images were also acquired at 30, 120, and 240 min to study biodistribution. Activity in each organ was expressed as percentage retained dose. Visual score (0-3) was used to categorize studies as positive or negative, with scores of 0 (minimal or no uptake; equivalent to soft tissue) and 1 (mild; less uptake than in liver) being considered negative and scores of 2 (moderate; uptake greater than or equal to that in liver) and 3 (intense; uptake greater than or equal to that in kidneys) being considered positive. Scans were interpreted as true- or false-positive and true- or false-negative on the basis of bacterial culture as the major criterion and the results of clinical tests, radiography, and 3-phase bone scanning as minor criteria. RESULTS: The biodistribution study showed a gradual decline in renal activity as percentage of administered dose from 6.53% +/- 0.58% at 30 min to 4.54% +/- 0.57% at 120 min and 3.38% +/- 0.55% at 240 min. The liver showed a similar trend, with values of 5.43% +/- 0.76%, 3.17% +/- 0.25%, and 2.02% +/- 0.30% at 30, 120, and 240 min, respectively. Radioactivity accumulated gradually in the urinary bladder, with values of 4.60% +/- 0.92% at 30 min, 23.00% +/- 2.32% at 120 min, and 38.85% +/- 4.01% at 240 min. Of 18 studies performed with 99mTc-UBI 29-41, 14 showed positive findings and 4 showed negative findings. Negative findings were subsequently confirmed to be true negative. The positive findings for 1 scan were interpreted as false positive, as no growth was obtained on bacterial culture and no evidence of infection was found on minor criteria. In 10 cases, the major criterion was used, whereas in 4 cases minor criteria had to be used for interpretation. Quantitative analysis revealed a maximum mean target-to-nontarget ratio of 2.75 +/- 1.69 at 30 min, which decreased to 2.04 +/- 1.01 at 120 min. The overall sensitivity, specificity, and accuracy were 100%, 80%, and 94.4%, respectively. No adverse reactions were observed during image acquisition and within 5 d after the study. CONCLUSION: 99mTc-UBI 29-41 showed promise in localizing foci of infection, with optimal visualization at 30 min.

Adolescent↗

PubMed2004

99mTc-labeled antimicrobial peptide ubiquicidin (29-41) accumulates less in Escherichia coli infection than in Staphlococcus aureus infection.

UNLABELLED: 99mTc-Labeled antimicrobial peptide ubiquicidin, (99m)Tc-UBI (29-41) in a freeze-dried kit, was evaluated as a bacterial infection-seeking agent in Staphlococcus aureus- and Escherichia coli-induced infections. METHODS: Thirty-three rabbits were classified in 3 groups. Biodistribution of (99m)Tc-UBI (29-41) was studied in 3 animals (group I). Uptake of peptide was determined by counting radioactivity in anatomically fitted regions drawn over the liver, kidneys, urinary bladder, and whole body and expressed as the percentage uptake per organ. Experimental thigh muscle infection was induced by injecting 2 x 10(8) colony-forming units of live S. aureus or E. coli bacteria into the right thigh muscle in 20 rabbits (group II). Turpentine oil and formalin-killed S. aureus were used for inducing sterile thigh muscle inflammation in 10 rabbits (group III). On scintigrams, anatomically adjusted regions of interest were drawn over infected/inflamed (target) and noninfected/noninflamed (nontarget) thigh, and accumulation of (99m)Tc-UBI (29-41) at sites of infection/inflammation was expressed as a target-to-nontarget (T/NT) ratio. RESULTS: A biodistribution study of (99m)Tc-UBI (29-41) revealed rapid removal of tracer from the circulation via the kidneys (10.6% +/- 2.1% at 5 min and 5.9% +/- 0.8% at 60 min) with accumulation of the major part in the urinary bladder within the first hour after injection (66.6% +/- 7.2%). A significantly higher (P < 0.05) accumulation of (99m)Tc-UBI (29-41) was seen at sites of S. aureus-infected animals (T/NT ratio, 2.2 +/- 0.5) compared with that of E. coli-infected animals (T/NT ratio, 1.7 +/- 0.4). The maximum tracer accumulation was observed at 60 min after injection followed by a gradual decline. No significant accumulation was noticed in thighs of rabbits injected with either turpentine oil or killed S. aureus with markedly lower T/NT ratios (P < 0.05) compared with that of S. aureus- and E. coli-infected thighs. CONCLUSION: A (99m)Tc-UBI (29-41) freeze-dried kit can be used for differentiating infections with S. aureus and E. coli with significantly higher scintigraphic intensity (P < 0.05) compared with that of sterile inflammatory sites. The optimum time for infection imaging is 60 min after injection. Relatively low (T/NT) ratios were observed in E. coli infections compared with those of the S. aureus group, which may be due to a low virulence of the former; however, other possible reasons may include low affinity of this peptide for E. coli microbial membranes.

Animals↗

PubMed2003

Standardization of the techniques evaluating endothelial functions.

Assessment of endothelial functions is an important area of medical research. Endothelial functions provide vital information for the management of coronary artery disease (CAD). As a measurable parameter, endothelial functions give a prognostic index that integrates the overall stress imposed by coronary risk factors. Evaluation of endothelial functions by non-invasive modes using ultrasound probes is a sensitive and hazard-free technique. However, standardization of the technique is of prime importance to generate a reliable data in the clinical practice.

Clinical Protocols↗

PubMed2003

Diagnosis of coronary artery disease by stress echocardiography and perfusion scintigraphy.

This meta-analysis was performed to compare the diagnostic efficacy of stress echocardiography (SE) and Stress perfusion studies (SPS) in detecting coronary artery disease (CAD). A meta-analysis of peer reviewed articles, published in English language, reporting head-to-head comparison of vasodilator stress echocardiography (VSE) and SPS for the diagnosis of CAD, was performed. Data of 13 studies comprising of 860 patients from 13 different institutions were analyzed. Algorithms were developed to generate raw data from published papers to calculate statistical parameters with confidence intervals and then compare them at specified significance levels. The overall diagnostic accuracy of the two tests was almost similar, 0.77 for VSE vs 0.8 for SPS (p=ns). SPS gave higher sensitivity, 0.88 vs 0.70 in cumulative data (p<0.0001) while VSE gave higher specificity, 0.90 vs 0.67 (p<0.0001). Accuracy of VSE with state-of-the-art protocols became even better than SPS (p<0.05). In hypertensive patients specificity of SPS was markedly deteriorated. Contrary to this, VSE gave higher specificity (0.90 vs 0.40) in this subgroup of patients as well. VSE might become an effective alternative of SPS where scintigraphy techniques are not available or affordable.

Coronary Artery Disease↗

PubMed2002

Clinical value of left atrial appendage flow for prediction of long-term sinus rhythm maintenance in patients with nonvalvular atrial fibrillation.

OBJECTIVES: This study evaluated the role of various clinical and echocardiographic parameters, including the left atrial appendage (LAA) anterograde flow velocity, for prediction of the long-term preservation of sinus rhythm (SR) in patients with successful cardioversion (CV) of nonvalvular atrial fibrillation (AF). BACKGROUND: Echocardiographic parameters for assessing long-term SR maintenance after successful CV of nonvalvular AF are not accurately defined. METHODS: Clinical, transthoracic echocardiographic and transesophageal echocardiographic (TEE) data--measured in AF lasting >48 h--of 186 consecutive patients (116 men, mean age: 65 +/- 9 years) with successful CV (electrical or pharmacologic) were analyzed for assessment of one-year maintenance of SR. RESULTS: At one-year follow-up, 91 of 186 (49%) patients who underwent successful CV continued to have SR. Mean LAA peak emptying flow velocity was higher in patients remaining in SR for one year than in those with AF relapse (41.7 +/- 20.2 cm/s vs. 27.7 +/- 17.0 cm/s; p < 0.001). On multivariate logistic regression analysis, only the mean LAA peak emptying velocity >40 cm/s (p = 0.0001; chi(2): 23.9, odds ratio [OR] = 5.2, confidence interval [CI] 95% = 2.7 to 10.1) and the use of preventive antiarrhythmic drug treatment (p = 0.0398; chi(2): 4.2; OR = 2.0, CI 95% = 1.0 to 3.8) predicted the continuous preservation of SR during one year, outperforming other univariate predictors such as absence of left atrial spontaneous echocardiographic contrast during TEE, the left atrial parasternal diameter <44 mm, left ventricular ejection fraction >46% and AF duration <1 week before CV. The negative and positive predictive values of the mean LAA peak emptying velocity >40 cm/s for assessing preservation of SR were 66% (CI 95% = 56.9 to 74.2) and 73% (CI 95% = 62.4 to 83.3), respectively. CONCLUSIONS: In TEE-guided management of nonvalvular AF, high LAA flow velocity identifies patients with greater likelihood to remain in SR for one year after successful CV. Low LAA velocity is of limited value in identifying patients who will relapse into AF.

Aged↗