Biomedical subjects

Michael Lieber

Publications and source records attributed to Michael Lieber.

12 recordsLinked to original sources

PubMed2006

The accuracy of chest radiographs in the detection of congenital heart disease and in the diagnosis of specific congenital cardiac lesions.

BACKGROUND: Congenital heart disease (CHD) is a significant cause of morbidity and mortality in pediatric patients. Traditional teaching holds that specific types of CHD can be diagnosed on the chest radiograph (CXR) through pattern recognition. OBJECTIVE: To determine the accuracy of radiologists in detecting CHD on the CXR. MATERIALS AND METHODS: This study was a blinded retrospective review of chest radiographs from 281 patients (<12 years) by five pediatric radiologists from three institutions. Thirteen groups were evaluated that included 12 categories of CHD and a control group of patients without heart disease. Radiographs were assessed for heart size, heart and mediastinal shape and vascularity. Clinical information, angiography, echocardiograms and surgery were used as the gold standard for definitive diagnosis. RESULTS: The average accuracy of the five readers in distinguishing normal from CHD patients was 78% (range of 72% to 82%). The overall measure of accuracy in distinguishing specific congenital cardiac lesions among 13 groups of patients was 71% (range of 63% to 79%). CONCLUSION: CXR alone is not diagnostic of specific cardiac lesions, with a low accuracy of only 71%. We believe that less emphasis should be placed on the use of radiographs alone in diagnosing specific congenital cardiac lesions.

Child↗

PubMed2006

Exercise-induced QT/R-R-interval hysteresis as a predictor of myocardial ischemia.

OBJECTIVES: Exercise-induced QT/RR hysteresis exists when, for a given R-R interval, the QT interval duration is shorter during recovery after exercise than during exercise. We sought to assess the association between QT/RR hysteresis and imaging evidence of myocardial ischemia. BACKGROUND: Because ischemia induces cellular disturbances known to decrease membrane action potential duration, we hypothesized a correlation between QT/RR and myocardial ischemia. METHODS: We digitally analyzed 4-second samples of QT duration and R-R-interval duration in 260 patients referred for treadmill exercise stress and rest single photon emission computed tomography myocardial perfusion imaging; a cool-down period was used after exercise. None of the patients were in atrial fibrillation or used digoxin, and none had marked baseline electrocardiographic abnormalities. Stress and rest myocardial perfusion images were analyzed visually and quantitatively to define the extent and severity of stress-induced ischemia. QT/RR hysteresis was calculated using a computerized algorithm. RESULTS: There were 82 patients (32%) who manifested myocardial ischemia by single photon emission computed tomography myocardial perfusion imaging. The likelihood of ischemia increased with increasing QT/RR hysteresis, with prevalence according to quartiles of 20%, 30%, 26%, and 49% (P = .003 for trend). In analyses adjusting for ST-segment changes, exercise capacity, heart rate recovery, and other confounders, QT/RR hysteresis was independently predictive of presence of myocardial ischemia (adjusted odds ratio for 100-point increase of QT/RR hysteresis, 1.61; 95% confidence interval, 1.22-2.12; P = .0008). QT/RR hysteresis was also predictive of severe ischemia. CONCLUSION: Exercise-induced QT/RR hysteresis is a strong and independent predictor of myocardial ischemia and provides additional information beyond that afforded by standard ST-segment measures.

Aged↗

PubMed2006

Contrast enhancement of coronary atherosclerotic plaque: a high-resolution, multidetector-row computed tomography study of pressure-perfused, human ex-vivo coronary arteries.

OBJECTIVES: The objective of this study was to investigate the effect of contrast injection on atherosclerotic coronary plaque attenuation measured using multidetector-row computed tomography. BACKGROUND: Recent multidetector-row computed tomography studies have described the characterization of coronary atherosclerotic plaque on the basis of Hounsfield unit values. The influence of contrast injection on the attenuation of individual plaque components, however, is unknown. METHODS: Using a pressurized perfusion system, 10 human coronary arteries were examined postmortem with multidetector-row computed tomography and histology. Pre-enhanced, peak-enhanced, and delayed enhanced multidetector-row computed tomography images were acquired during continuous perfusion of the vessel. A total of 37 focal atherosclerotic plaques were identified. Vessel wall attenuation was measured from multidetector-row computed tomography images during all three enhancement phases. On the basis of the histology, plaques were categorized as noncalcified (predominantly fibrous or predominantly fibrofatty), mixed calcified (calcified fibrous or calcified necrotic core), or densely calcified. The mean Hounsfield unit was compared among contrast phases for all plaques and in plaque subgroups. RESULTS: We observed contrast enhancement of atherosclerotic plaques within the vessel wall. For noncalcified plaques including both fibrous and fibrofatty plaques, the mean Hounsfield unit of the vessel wall during and after contrast injection exceeded the mean value before injection (t-test, P<0.002). CONCLUSION: The present study demonstrates that intra-arterial injection of iodinated contrast agent results not only in luminal enhancement but also in atherosclerotic plaque enhancement in pressure-perfused coronary arteries imaged ex vivo. Plaque enhancement should be considered when characterizing plaque components on the basis of Hounsfield unit with multidetector-row computed tomography.

Adult↗

PubMed2005

Potential clinical impact of variability in the measurement of coronary artery calcification with sequential MDCT.

OBJECTIVE: The potential clinical impact of variability in the measurement of coronary artery calcification with sequential MDCT was evaluated using Agatston, volume, and mass scoring algorithms. SUBJECTS AND METHODS: Fifty-six patients were imaged twice using an identical prospectively ECG-triggered sequential scanning protocol. The Agatston, volume, and mass scores were computed by two observers independently. In addition, a patient's total Agatston score was referenced to an age- and sex-stratified database to determine a percentile ranking. Interscan, interobserver, and intraobserver variability and the resultant impact on patients' risk stratifications were assessed. RESULTS: Significant interscan differences were found for all mean coronary calcium scores (Wilcoxson's signed rank test, p <0.0001). Although the median percentage of interscan variability was low for all scoring methods, the interquartile range was wide, indicating significant variability in the data. Median scores (lower quartile-upper quartile) for observers 1 and 2, respectively, were as follows: Agatston, 5% (0-79%) and 6% (0-83%); volume, 12% (0-51%) and 12% (0-57%); and mass, 14% (0-57%) and 14% (0-58%). Interobserver and intraobserver differences between mean calcium scores were not significant, and consequently, lower interobserver and intraobserver variabilities (narrow interquartile ranges of 0-5%) were observed for all scores. Despite significant interscan differences in calcium scores, the percentile ranking assigned to the two scans differed in only 13% of patients. Interobserver differences resulted in a change in the percentile ranking in 7-9% of patients, whereas intraobserver differences caused a change in only 5% of patients. CONCLUSION: The accuracy of sequential MDCT for coronary calcium quantification is sufficient in most cases for stratification of patient risk.

Adult↗

PubMed2004

The efficacy of hyperbaric oxygen therapy in the treatment of radiation-induced late side effects.

PURPOSE: We investigated the efficacy of hyperbaric oxygen therapy (HBOT) in the management of patients with radiation-induced late side effects, the majority of whom had failed previous interventions. METHODS AND MATERIALS: Of 105 eligible subjects, 30 had either died or were not contactable, leaving 75 who qualified for inclusion in this retrospective study. Patients answered a questionnaire documenting symptom severity before and after treatment (using Radiation Therapy Oncology Group criteria), duration of improvement, relapse incidence, and HBOT-related complications. RESULTS: The rate of participation was 60% (45/75). Improvement of principal presenting symptoms after HBOT was noted in 75% of head-and-neck, 100% of pelvic, and 57% of "other" subjects (median duration of response of 62, 72, and 68 weeks, respectively). Bone and bladder symptoms were most likely to benefit from HBOT (response rate, 81% and 83%, respectively). Fifty percent of subjects with soft tissue necrosis/mucous membrane side effects improved with HBOT. The low response rate of salivary (11%), neurologic (17%), laryngeal (17%), and upper gastrointestinal symptoms (22%) indicates that these were more resistant to HBOT. Relapse incidence was low (22%), and minor HBOT-related complications occurred in 31% of patients. CONCLUSION: Hyperbaric oxygen therapy is a safe and effective treatment modality offering durable relief in the management of radiation-induced osteoradionecrosis either alone or as an adjunctive treatment. Radiation soft tissue necrosis, cystitis, and proctitis also seemed to benefit from HBOT, but the present study did not have sufficient numbers to reliably predict long-term response.

Adolescent↗

PubMed2004

Effectiveness of salmon calcitonin nasal spray in the treatment of lumbar canal stenosis: a double-blind, randomized, placebo-controlled, parallel group trial.

STUDY DESIGN: Double-blind, randomized, placebo-controlled study to assess the effectiveness of calcitonin nasal spray on symptoms and function in patients with lumbar canal stenosis. OBJECTIVE: To compare effectiveness of calcitonin administered by nasal spray with placebo in patients with clinically symptomatic lumbar canal stenosis. SUMMARY OF BACKGROUND DATA: Lumbar canal stenosis is the most common reason for spine surgery in individuals over 65 years of age. Nonoperative approaches have been not well studied and limited primarily to physical therapy exercises. Several small trials in the past have suggested that subcutaneous and intramuscular calcitonin is an effective nonsurgical option in treating the symptoms of spinal stenosis patients. Only three trials were randomized and placebo-controlled. METHODS: Fifty-five patients with clinical lumbar canal stenosis (pseudoclaudication), confirmatory MR imaging, and pain intensity index (VAS) of > or =6 were randomized to either placebo or intranasal calcitonin daily for 6 weeks, followed by an open label 6-week extension, during which all patients received active drug. Outcome parameters performed at baseline, 6 weeks, and 12 weeks, included pain intensity index, walking time and distance to pain, SF-36, and Oswestry disability index. RESULTS: Thirty-six patients received calcitonin, and 19 placebo. Eight (14.54%) calcitonin and 4 (7.27%) placebo patients withdrew from the study. The mean baseline pain score for calcitonin group was 7.8 and 7.5 for placebo. Comparisons at week 6 showed no statistically significant difference in the change in pain intensity (VAS) between calcitonin group (-2.9) and placebo (-2.4) (P = 0.4382) from baseline. There was no significant difference in walking time to pain (calcitonin -10.0 seconds; placebo +32.2 seconds; P = 0.5136). Walking distance to pain showed a mean improvement of +91.4 ft in the calcitonin group and +254.7 ft in the placebo group (P = 0.4948). No significant difference was observed in the SF-36 score between the treatment groups. Using a threshold of at least 50% reduction in pain from baseline to 6 weeks, 12 of 29 (41.37%) of calcitonin patients were considered responders versus 7 of 18 (38.88%) of placebo patients (P = 0.4238) CONCLUSIONS: In this first ever largest randomized placebo-controlled parallel group trial of nasal calcitonin in spinal stenosis, nasal calcitonin was not superior to placebo in treating the symptoms of spinal stenosis at 6 weeks. Based on this study, nasal calcitonin does not appear to have a role in nonoperative treatment of lumbar canal stenosis.

Administration, Intranasal↗

PubMed2004

Impact of age and hyperglycemia on the mechanical behavior of intact human coronary arteries: an ex vivo intravascular ultrasound study.

Despite their advantages, percutaneous coronary interventional procedures are less effective in diabetic patients. Changes in the mechanical properties of vascular walls secondary to long-term hyperglycemia as well as other factors such as age may influence coronary distensibility. This investigation is aimed at deciphering the extent of these effects on distensibility of postmortem human coronary arteries in a controlled manner. Excised human left anterior descending (LAD) coronary arteries were obtained within 24 h postmortem. With the use of intravascular ultrasound, vascular deformation was analyzed at midregions of 51 moderate lesions. Intraluminal pressure was systematically altered using a computerized pressure pump system and monitored by a pressure-sensing guidewire. Distensibility, a normalized compliance term, was defined as the change in lumen area normalized by the initial reference area over a given pressure interval. With the use of multivariate analysis and repeated-measures ANOVA, coronary distensibility was independently influenced by hyperglycemia and age (P < 0.05) through the entire pressure range. Within physiological pressure range, distensibility was significantly reduced with age in nonhyperglycemic coronary specimens (10.55 +/- 4.41 vs. 6.99 +/- 2.45, x10(3) kPa(-1), P = 0.01), whereas the hyperglycemic vessels were stiff even in the younger group (7.90 +/- 5.82 vs. 7.20 +/- 3.36, x10(3) kPa(-1), P = 0.79). Similar results were observed with stiffness index and elastic modulus of the arteries. Hyperglycemia and age independently influenced the distensibility of moderately atherosclerotic LAD coronary arteries. The stiffening with age was overshadowed in the hyperglycemic group by as-yet-undetermined factors.

Aging↗

PubMed2003

Do segmented reconstruction algorithms for cardiac multi-slice computed tomography improve image quality?

PURPOSE: To evaluate segmented reconstruction algorithms for spiral multi-slice computed tomography (MSCT) that use data from two cardiac cycles to improve temporal resolution (tau) for imaging of the heart. MATERIALS AND METHODS: An initial group of 78 cardiac patients (heart rates [HR] = 63-167 beats per minute [bpm]) were imaged on a 4-slice, 500 ms gantry rotation time scanner (scanner 1). Images were reconstructed with a single-segment algorithm using data from one cardiac cycle with a reconstruction window of fixed length (tau = 250 ms). Images were also reconstructed with two variants of a multi-segment algorithm using data from two cardiac cycles where only one end of the reconstruction window was fixed and the other end was freely moveable to allow adjustment of tau according to HR: (1) "2-segment fixed start" with fixed start of reconstruction, (2) "2-segment fixed end" with fixed end of reconstruction (for both, tau = 125-250 ms). The resulting image sets were ranked from best to worst (1-3, respectively) in a side-by-side, blinded comparison by two independent readers. A second group of 26 patients (HR = 74-90 bpm) were imaged on a 12-slice, 420 ms gantry rotation time scanner (scanner 2). Data were reconstructed with a single-segment algorithm (tau = 210 ms) and a "2-segment fixed start" algorithm (tau = 105-210 ms) and image sets were ranked from best to worst (1-2, respectively). RESULTS: There was no clear evidence that any one technique is superior for imaging on scanner 1. Reader 1 ranked single-segment images the highest for all HRs, but statistically significant differences among the three algorithms were only found for the lowest HRs (< 80 bpm), where reader 1 preferred single-segment over "2-segment fixed end" techniques (p = 0.048). The highest rankings given by reader 2 varied according to HR: single-segment images were superior for lowest HRs, while "2-segment fixed start" images were superior for HRs > 80 bpm; none of these comparisons reached statistical significance. Improved performance of 2-segment reconstruction was found with scanner 2. Both readers ranked "2-segment fixed start" images the highest (p < 0.01). CONCLUSIONS: The added value of 2-segment cardiac reconstruction algorithms for spiral MSCT was not demonstrated for a 4-slice, 500 ms gantry rotation time scanner but shown to be beneficial for a 12-slice, 420 ms gantry rotation time scanner in the crucial HR range of 74-90 bpm.

Adolescent↗

PubMed2003

Long-term 6-year experience with finasteride in patients with benign prostatic hyperplasia.

OBJECTIVES: To summarize the 6-year clinical trial data with finasteride. Benign prostatic hyperplasia is a chronic and progressive disease and therefore assessment of long-term safety and efficacy is important. METHODS: The North American and International Phase III Finasteride trials enrolled symptomatic men with enlarged prostate glands. The initial 1-year placebo-controlled study was followed by a 5-year open-label extension. In total, 6-year finasteride data were available in 487 patients originally randomized to finasteride, and 5-year data were available on 238 patients originally randomized to placebo. RESULTS: After 6 years of treatment with finasteride 5 mg, the mean quasi-American Urological Association Symptom Score improved by 4.0 points, the median prostate volume decreased by 24%, and the mean maximal urinary flow rate increased by 2.9 mL/s (P <0.001 for all parameters). Long-term finasteride treatment was well tolerated, with a low incidence of drug-related sexual adverse events occurring during the first year and even fewer occurrences during the 5-year open extension. CONCLUSIONS: Treatment with finasteride leads to durable improvement in urinary tract symptoms, flow rate, and prostate volume, with no increase in the prevalence of drug-related adverse events over time.

5-alpha Reductase Inhibitors↗

PubMed2002

Clinical evaluation of a multi-target fluorescent in situ hybridization assay for detection of bladder cancer.

PURPOSE: The UroVysion fluorescence in situ hybridization assay (UroVysion Bladder Cancer Recurrence Kit, Vysis, Inc., Downers Grove, Illinois) is a multi-target assay that detects aneuploidy of chromosomes 3, 7 and 17, and loss of the 9p21 band in exfoliated cells in urine from patients with transitional cell carcinoma. We performed 2 multicenter trials. In 1 trial we compared the sensitivity of the FISH assay to the BTA Stat test (Bion Scientific, Redmond, Washington) and voided cytology in the detection of transitional cell carcinoma. In a separate study of healthy volunteers and patients with other (nontransitional cell carcinoma) conditions we determined the specificity of the FISH assay. MATERIALS AND METHODS: A total of 176 patients with transitional cell carcinoma in the previous 9 months provided voided urine before cystoscopy. Each specimen was split, preserved and shipped to a central laboratory where all 3 tests were performed. All sites were blinded to results. Sensitivity calculations were based on central pathology review of resected tissue. Specificity was determined by testing 275 volunteers who were healthy and with nontransitional cell carcinoma conditions. RESULTS: The 21 sites enrolled 176 patients with a history of transitional cell carcinoma, with 62 recurrences while undergoing surveillance. Overall sensitivities (with 95% CI) were FISH 71% (95% CI 58 to 82), BTA Stat test 50% (37 to 63) and cytology 26% (16 to 39). FISH was negative in 260 of the 275 healthy volunteers or patients with no history of transitional cell carcinoma (specificity 94.5%). CONCLUSIONS: Sensitivity of the FISH assay is superior to that of cytology and at least equivalent to the BTA Stat test in detecting recurrent transitional cell carcinoma. Its specificity approaches that of cytology. Further testing of its clinical use is warranted.

Adult↗

PubMed2002

Concomitant longitudinal changes in frequency of and bother from lower urinary tract symptoms in community dwelling men.

PURPOSE: Care for men with benign prostatic hyperplasia consumes a sizable amount of health care resources, which is largely driven by bother from lower urinary tract symptoms. While cross-sectional studies have demonstrated a strong correlation between frequency of symptoms and associated bother, there are few longitudinal data demonstrating how these track together. MATERIALS AND METHODS: In 1989, 2,115 white men between 40 and 79 years old were recruited from a random sample of the Olmsted County population. These men completed a self-administered questionnaire that assessed lower urinary tract symptom severity and associated bother with questions similar to those in the American Urological Association Symptom Index. Questionnaires were completed biennially thereafter through 1996. RESULTS: Annualized changes in symptom score increased from a median of 0.02 per year (25th, 75th percentile -0.35, 0.60) for men in their forties to 0.43 (-0.12, 1.16) for men in their sixties. The median change in bother scores was 0 (-0.30, 0.29) across all ages. The correlation between longitudinal symptom score slopes and bother score slopes was 0.55 (p <0.001) overall and did not differ substantively across age. CONCLUSIONS: These results demonstrate that there is a great deal of variability between individuals in the amount of longitudinal change in lower urinary tract symptom severity and bother. While for bother, there is little change across individuals on average, within individual frequency and bother track together fairly closely. However, there remain some men with increases in frequency who do not report similar increases in bother, possibly representing some component of adaptation or acceptance of worsening symptom severity with age.

Adult↗

PubMedDate not supplied

The mind's eye: functional MR imaging evaluation of golf motor imagery.

BACKGROUND AND PURPOSE: Mental imagery involves rehearsing or practicing a task in the mind with no physical movement. The technique is commonly used, but the actual physical foundation of imagery has not been evaluated for the fast, complex, automatic motor movement of the golf swing. This study evaluated motor imagery of the golf swing, of golfers of various handicaps, by using functional MR imaging to assess whether areas of brain activation could be defined by this technique and to define any association between activated brain areas and golf skill. METHODS: Six golfers of various handicap levels were evaluated with functional MR imaging during a control condition and during mental imagery of their golf swing. Two control conditions were evaluated--"rest" and "wall"--and were then subtracted from the experimental condition to give the functional activation map. These control conditions were then tested against the golf imagery; the participants were told to mentally rehearse their golf swings from a first person perspective. The percentages of activated pixels in 137 defined regions of interest were calculated. RESULTS: The "rest-versus-golf" paradigm showed activation in motor cortex, parietal cortex, frontal lobe, cerebellum, vermis, and action planning areas (frontal and parietal cortices, supplementary motor area, cerebellum) and areas involved with error detection (cerebellum). Vermis, supplementary motor area, cerebellum, and motor regions generally showed the greatest activation. Little activation was seen in the cingulate gyrus, right temporal lobe, deep gray matter, and brain stem. A correlation existed between increased number of areas of activation and increased handicap. CONCLUSION: This study showed the feasibility of defining areas of brain activation during imagery of a complex, coordinated motor task. Decreased brain activation occurred with increased golf skill level for the supplementary motor area and cerebellum with little activation of basal ganglia.

Adult↗