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E Halpern

Publications and source records attributed to E Halpern.

34 records · Page 2Linked to original sources
PubMed1994

Application of wavelet compression to digitized radiographs.

OBJECTIVE: Image data compression is an enabling technology for teleradiology and picture archive and communication systems. Compression decreases the time and cost of image transmission and the requirements for image storage. Wavelets, discovered in 1987, constitute a new compression technique that has been described in radiologic publications but, to our knowledge, no previous studies of its use have been reported. The purpose of this study was to demonstrate the application of wavelet-based compression technology to digitized radiographs. MATERIALS AND METHODS: Twelve radiographs with abnormal findings were digitized, compressed, and decompressed by using a new wavelet-based lossy compression algorithm. Images were compressed at ratios from 10:1 to 60:1. Seven board-certified radiologists reviewed images on a two-headed, high-resolution (2K x 2K) diagnostic workstation. Paired original and compressed/decompressed images were presented in random order. Reviewers adjusted contrast and magnification to judge whether image degradation was present, and if so, whether it was of diagnostic significance. Quantitative error measures were tabulated. RESULTS: Reviewers found no clinically relevant degradation below a compression ratio of 30:1. Skeletal radiographs appeared more sensitive to compression than did chest or abdominal radiographs, but the trend was not statistically significant. Quantitative error measures increased gradually with compression ratio. CONCLUSION: On the basis of subjective assessment of image quality and the computational efficiency of the algorithm, wavelet-base techniques appear promising for the compression of digitized radiographs. The results of this initial experience can be used to design appropriate observer performance studies.

Adult↗
PubMed1993

The futility of the chest radiograph in the febrile infant without respiratory symptoms.

OBJECTIVE: Major pediatric textbooks advocate a chest radiograph as part of the diagnostic evaluation for a sepsis workup for febrile infants less than 3 months old. Very few studies have addressed the value of performing a chest radiograph in this situation. Two studies previously published lack the numbers to statistically justify a conclusion about the need to perform a chest radiograph in the febrile infant. METHODS: Evaluated were 197 febrile infants 3 months old or less with a history, physical examination, chest radiograph, and other laboratory studies to determine the cause of their fever. This group of infants was combined with the group of infants from two similar studies published previously in the literature using cumulative meta-analysis. The combined group resulted in 617 infants. RESULTS: The combined group of infants had 361 infants who had no clinical evidence of pulmonary disease on history or physical examination. All 361 infants had normal chest radiograph. These results gave a 95% confidence interval that the chance of a positive chest radiograph in a patient with no pulmonary symptoms would occur less than 1.02% of the time. CONCLUSIONS: The generally advocated policy of obtaining a chest radiograph as part of the sepsis workup in febrile infants should be discontinued, and chest radiographs should be obtained only in febrile infants who have clinical indications of pulmonary disease.

Fever of Unknown Origin↗
PubMed1991

The use of iohexol in patients with previous reactions to ionic contrast material. A multicenter clinical trial.

Patients who have had prior reactions to iodinated contrast material have increased risk for repeat reactions. Nonionic contrast agents have been reported to reduce the risk of contrast reactions. A multicenter study was undertaken to determine the repeat reaction rate using iohexol. Two hundred ninety-one repeat reactors were included in the study, of whom one-third received premedication. Sixteen patients (5.5%) experienced repeat reactions; none was severe, and only one was more serious than the prior reaction. This is in contrast to the reported 16% to 44% repeated reaction rate for ionic agents. We conclude that iohexol is effective in reducing the occurrence of repeat reactions from the level observed with ionic agents without premedication. Iohexol appears to be as effective as ionic agents plus premedication in this high-risk group of patients.

Adult↗
PubMed1990

[Obstructive sleep apnea treated with uvulopalato-pharyngoplasty].

38 patients with sleep apnea syndrome treated with uvulopalato-pharyngoplasty were interviewed 23 +/- 10.8 months after the operation (mean age 48.0 +/- 8.6 years, range 28-65). 22 were also studied in the sleep laboratory 10 +/- 10.7 months after operation. 3 months after operation 94% reported improvement in snoring and 77% improvement in excessive daytime sleepiness. 1 and 2 years after the operation snoring had decreased to 74% and 65%, respectively, and excessive sleepiness to 65%, for both periods. There was a decrease of at least 50% in the number of apneic periods per hour of sleep in 68%. Side-effects consisted of nasal regurgitation and vocal changes. Only age was of predictive value: the younger the patient the better the response.

Adult↗
PubMed1982

Apneic and nonapneic breathing disorders in sleep.

Recent research has demonstrated that respiratory activities are stage dependent and that some breathing disorders appear only in sleep. Sleep apnea syndromes, defined as the occurrence of at least 30 apneas of greater than or equal to 10 sec, dramatically affect patients' sleep and waking behavior. During 1977-80, 114 patients with sleep apnea and 82 patients with nonapneic breathing disorders in sleep, were recorded in the Technion Sleep Laboratory. In both groups, patients were mostly male in the 30- to 50-yr age-group, whose primary complaint was excessive daytime sleepiness. Nonapneic breathing disorders in sleep included periodic breathing, periodic hyperpnea, and variations in rate of breathing without notable changes in volume. It is suggested that some of the patients with sleep apnea syndrome and with non-apneic breathing disorders in sleep belong to the same etiological group, each representing a different stage along a single continuum of breathing disorders.

Adult↗
PubMed1982

Excessive daytime sleepiness and insomnia.

Twenty-five adults with a deviated nasal septum, who complained about excessive daytime sleepiness, chronic fatigue, and nocturnal insomnia, were studied for one to two nights in a sleep laboratory. Recordings disclosed disordered breathing during sleep in the form of pronounced periodic breathing of alternating hypopneas and hyperpneas, isolated hypopneic episodes and central apneas and periodic sighs, all combined with electrophysiologic "microarousals," and a mixture of alpha and delta EEG wave activities. Surgical treatment of the deviated septum in 14 patients resulted in a subjective improvement in the level of diurnal alertness and in the quality of nocturnal sleep in 12 patients. Follow-up sleep recordings in seven of the patients who reported subjective improvement in sleep disclosed notably less waking and abnormal breathing during sleep. These results suggest that increased upper airway resistance can cause nonapneic breathing disorders in sleep and, consequently, sleep disturbances.

Adult↗
PubMed1981

Role of sulA and sulB in filamentation by lon mutants of Escherichia coli K-12.

Cells containing the pleiotropic Escherichia coli mutation lon filament extensively and die after exposure to ultraviolet light. Outside suppressors of the ultraviolet sensitivity, called sul, have previously been described at two loci; these mutations reverse the ultraviolet sensitivity of lon strains but do not affect the mucoidal or degradation defect of these strains. An isogenic set of strains carrying combinations of lon, sulA, and sulI was constructed, and their behavior during normal growth and after ultraviolet treatment was studied. sulA mutations had no detectable phenotype in lon+ cells; the lon sulA strains filamented transiently after ultraviolet irradiation, as did lon+ sul+ cells. We found that the sulB mutation, which alters cell morphology and slows recovery from transient filamentation after ultraviolet treatment, was epistatic to both lon and sulA. Whereas sulA mutations were recessive to the wild-type allele, sulB was partially dominant. The simplest model to account for our observations is that sulA and lon participate in a pathway of filamentation independent of that which produces transient filamentation in wild-type strains; sulB product may be the target of sulA action and may play a role in normal cell division.

Cell Division↗
PubMed1979

5-drug adjuvant chemotherapy for breast cancer.

A series of 41 patients at the MGH who received 5-drug chemotherapy, cyclophosphamide, methotrexate, 5-fluorouracil, vincristine and prednisone, (CMF VP) as adjuvant to surgical treatment of operable breast cancer with 4 or more positive axillary nodes is compared to an analogous group of patients treated with cyclophosphamide, methotrexate and 5-fluorouracil (CMF) reported by Bonadonna et al. in an effort to assess the contribution of the treatment program to disease control. The MGH pattern of disease free survival closely parallels that of Bonadonna. Median disease-free survival among the 24 patients who have not recurred is 27 months; among those who recurred 18 months. The analogous medians for treated patients in the Bonadonna study are 24 months and 16 months, as compared to 27 months and 8 months for his nontreated controls. The treatment program, carried out over a two year period, was well tolerated with excellent patient compliance. There was no significant impact, however, in the disease-free survival of postmenopausal patients. While use of this regimen improved disease-free survival in premenopausal individuals, it is clear that a great deal of room for improvement exists, and newer regimens should be investigated.

Antineoplastic Agents↗
PubMedDate not supplied

Contrast-enhanced MR imaging of the liver: comparison between Gd-BOPTA and Mangafodipir.

The purpose of the study was to evaluate the MR contrast agents gadolinium benzyloxypropionictetro-acetate (Gd-BOPTA) and Mangafodipir for liver enhancement and the lesion-liver contrast on T1W spin-echo (SE) and gradient-recalled-echo (GRE) images. Fifty-one patients (three groups of 17 patients each) with known or suspected liver lesions were evaluated with T1W SE (300/12) and GRE (77-80/2.3-2.5/80 degrees) images before and after intravenous (IV) Gd-BOPTA (0.1 or 0.05 mmol/kg) or Mangafodipir (5 mumol/kg) in phase II to III clinical trials. Quantitative analysis by calculating liver signal-to-noise ratio (SNR), lesion-liver contrast-to-noise ratio (CNR), and spleen-liver CNR was performed. Liver SNR and spleen-liver CNR were always significantly increased postcontrast. SNR was highest after application of 0.1 mmol/kg Gd-BOPTA (51.3 +/- 3.6, P < .05). CNR was highest after Mangafodipir (-22.6 +/- 2.7), but this was not significantly different from others (P = .07). Overall, GRE images were superior to SE images for SNR and CNR. Mangafodipir and Gd-BOPTA (0.1 mmol/kg) provide equal liver enhancement and lesion conspicuity postcontrast. By all criteria, contrast-enhanced T1-weighted GRE were comparable to SE images.

Adult↗
PubMedDate not supplied

Acquired tracheomalacia: detection by expiratory CT scan.

PURPOSE: The purpose of this work was to determine whether cross-sectional area and coronal and sagittal diameter measurements of the trachea between inspiration and end-expiration on CT are significantly different between patients with acquired tracheomalacia and those without this condition. METHOD: Inspiratory and end-expiratory CT scans of the trachea of 23 normal patients and 10 patients with acquired tracheomalacia were analyzed. Percent changes in cross-sectional area, coronal, and sagittal diameters were calculated. RESULTS: For patients with tracheomalacia, mean percent changes in the upper and middle trachea between inspiration and expiration were 49 and 44%; mean changes in the coronal and sagittal diameters in the upper and middle tracheal were 4 and 10% and 39 and 54%, respectively. Control group mean percent changes in the upper and middle tracheal area were 12 and 14%, respectively, and mean changes in the coronal and sagittal diameters in the upper and middle trachea were 4 and 4% and 11 and 13%, respectively. Significant differences were calculated for changes in cross-sectional area and sagittal diameter between groups (p < 10-5). Based on receiver operator curve analysis, a > 18% change in the upper trachea and 28% change in the midtrachea between inspiration and expiration were observed; the probability of tracheomalacia was 89-100%. The probability of tracheomalacia was > 89%, especially if the change in sagittal diameter was > 28%. CONCLUSION: By measuring changes in tracheal cross-sectional area and sagittal diameters between inspiratory and end-expiratory CT, a significant difference can be identified between normal patients and those with acquired tracheomalacia.

Adult↗