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Biomedical subjects

A Frenkel

Publications and source records attributed to A Frenkel.

At least 55 records · Page 3Linked to original sources

Normal and abnormal Ga-67 SPECT anatomy in patients with lymphoma.

The appearance of normal Ga-67 SPECT images in the coronal, sagittal and transaxial planes is described. The normal tomographic appearance of bone, liver, spleen, and gut is shown and compared with disease involvement above and below the diaphragm.

Gallium Radioisotopes↗

Functional changes in the brainstem auditory pathways following open-heart surgery.

Measurements of the auditory brainstem responses (ABR) were used to assess the functional integrity of the brainstem auditory pathways following open-heart surgery. Recording of ABR was performed in 31 patients before and after open-heart surgery. The values of ABR measurements were compared to those of a control group of normal-hearing subjects. Postoperative aberrations in ABR were observed in 12 patients. Brainstem transmission time measured as wave I to wave V interpeak latency (I-V IPL) was prolonged in 6 patients and shortened in 8 patients. Concomitant impairment in hearing function was not present, and therefore, these changes most probably reflected a functional alteration in the neurological status of the brainstem. Possible explanations of the postoperative changes in I-V IPL are discussed, however, further studies are needed to clarify the pathogenesis of these changes. Measurement of ABR may prove to be an important adjunct in the overall assessment of the neurological status following open-heart surgery.

Adult↗

Administered dose and tumor dose of bleomycin labeled with cobalt-57 in mice and men.

Tumor concentrations of the chemotherapeutic drug, bleomycin, labeled with cobalt-57 (Co-bleo) were compared in mouse tumor models and in human lung tumors using quantitative single-photon emission computed tomography. Drug concentrations in histologically similar human tumors showed marked variability for the same injected dose (ID). Small cell carcinomas showed concentrations between 1.09 and 8.85 %ID/cc x 10(-3) while non-small cell lung tumors showed a concentration variation between 0.36 and 6.75 %ID/cc x 10(-3). In contrast to the situation in human tumors, uptake in mouse tumors showed only slight variability in animals with the same tumor model. EMT-6 tumors in mice showed at 6 hr significantly higher uptake of Co-bleo (p less than 0.001) and significantly higher tumor-to-lung ratio (p less than 0.001) when compared to murine fibrosarcomas. The EMT-6 tumors in contrast to the fibrosarcomas responded to bleomycin treatment in a dose dependent manner. The results indicate that while in mice the tumor dose closely follows the administered dose, in humans, the tumor dose and the tumor-to-lung ratio in the individual patient cannot be predicted from the administered dose.

Aged↗

Efficacy of long-term fluoxetine treatment of obsessive-compulsive disorder.

Ten outpatients meeting DSM-III-R criteria for obsessive-compulsive disorder completed a 32-week, open-label study with fluoxetine, a selective serotonin reuptake blocker. The patients were evaluated every four weeks for obsessive-compulsive symptomatology, anxiety, and depression. Significant improvement of obsessive-compulsive and anxiety measures were observed after four weeks, with maximal improvement at eight weeks. Depressed and nondepressed patients showed similar rates of improvement in obsessive-compulsive symptomatology. Overall, fluoxetine was tolerated well by all patients, and no serious side effects were observed. This study suggests that fluoxetine is an effective and safe treatment for obsessive-compulsive disorder, both for short-term alleviation and for long-term maintenance.

Body Weight↗

SPECT quantitation of iodine-131 concentration in phantoms and human tumors.

The validity of SPECT measurement of iodine-131 (131I) concentration was tested in vitro in phantoms and in vivo by measuring bladder urine concentrations. Phantom studies comparing known and SPECT measured concentrations showed a good correlation for 131I (r = 0.98, s.e.e. = 20.94 counts/voxel) for phantoms of 25 to 127 cc and concentrations of 0.13 to 9.5 microCi/cc. The in vivo, in vitro correlation of 131I concentrations in the urine was also good (r = 0.98, s.e.e. = 0.677 microCi/cc). Quantitative SPECT was used to calculate the effective half-life and dosimetry of radioiodine in 12 sites of thyroid carcinoma in seven patients. SPECT was also used to determine the dosimetry of [131I]MIBG (metaiodobenzylguanidine) in two patients with carcinoid, two with neuroblastoma, and one with pheochromocytoma. The radiation dose for thyroid carcinoma metastases varied between 6.3 and 276.9 rad/mCi. The dose from MIBG varied between 13.4 and 57.8 rad/mCi. These results indicate the validity of quantitative SPECT for in vivo measurement of 131I and the need to measure the concentration of 131I in individual human tumor sites.

3-Iodobenzylguanidine↗

The concentration of bleomycin labeled with Co-57 in primary and metastatic tumors.

The concentration over time of bleomycin labeled with Co-57 was measured in 39 primary and metastatic tumor sites in 16 patients using a newly developed and validated single photon emission computed tomography (SPECT) method. There were nine primary tumors, 15 metastatic tumors, and five multifocal lymphomas. Co-bleomycin concentrations also were measured in primary and metastatic B-16 melanoma tumors in mice. In humans, metastases to lymph nodes (1.58 +/- 0.51 %ID/ml X minutes) showed significantly higher (P less than 0.01) tumor cumulative concentrations of Co-bleomycin than metastases to liver, bone, lung, and brain (0.76 +/- 0.20 %ID/ml X minutes). The cumulative concentrations of Co-bleomycin in human lymphomas (1.1 +/- 0.25 %ID/ml X minutes) also were significantly higher (P less than 0.01) than the concentrations in human metastases other than lymph nodes. The cumulative concentration in cerebral metastases (0.65 +/- 0.18 %ID/ml X minutes) was significantly lower (P less than 0.05) than in noncerebral metastases (1.22 +/- 0.53 %ID/ml X minutes). Primary tumors in humans showed higher concentrations of Co-bleomycin than metastases, except for lymph nodes. In contrast with humans, murine metastases showed higher concentrations of Co-bleomycin (6.20 +/- 2.65 %ID/g) than primary tumors (2.94 +/- 0.90 %ID/g) (P less than 0.001). The concentrations of Co-bleomycin in murine tumors that were affected by bleomycin were about three orders of magnitude higher than in human tumors. The results of this in vivo study document the differences in drug delivery of Co-57-labeled bleomycin to human primary and metastatic tumors and show differences in drug delivery between human and murine tumors.

Adolescent↗

A practical SPECT technique for quantitation of drug delivery to human tumors and organ absorbed radiation dose.

A practical quantitative single photon emission computed tomographic (SPECT) technique based on an empirical threshold analysis permits accurate measurements in humans of drug delivery and absorbed radiation dose. The limits of the method have been explored using a wide range of phantom volumes, concentrations, and target-to-nontarget ratios. A threshold of 43% was found to give the best results using volumes of 30 to 3,800 cc. An excellent correlation (r = .99 with a standard error of estimate [SEE] of 41 cc) was found between SPECT measured volumes and actual phantom volumes. A similarly high correlation (r = .98, SEE = 260 counts/voxel) was found in 77 measurements of concentrations between 0.01 and 3.6 microCi/cc. There was a direct relationship between the target-to-nontarget ratio of phantoms and the accuracy of volume measurements. The technique has been validated by an excellent in vivo/in vitro correlation of uptake in human tumors. The tumor cumulative concentration and tumor-to-blood ratio were used for assessment of drug delivery. In vivo quantitative measurements of the pharmacokinetics of technetium-99m (99mTc) glucoheptonate, cobalt-57 (57Co) bleomycin and platinum-195m (195mPt) cisplatin in human tumors in vivo indicates that, in contrast with tumor models in animals, there is a marked variability in drug delivery even in tumors with the same histology. Future development of labeled drugs should make it possible to use quantitative SPECT for predicting tumor response to therapy and for tailoring chemotherapy for the individual patient under treatment. SPECT quantitation of organ concentration was used for Medical Internal Radiation Dose committee (MIRD) calculations of organ absorbed radiation dose from 99mTc-labeled RBCs. Excellent in vivo/in vitro correlations were obtained between SPECT measured concentrations of blood radioactivity in the heart and in vitro measurements of blood samples. The possibilities and limitations of this technique are discussed and its use for in vivo measurement in humans of absorbed radiation dose from radiopharmaceuticals is suggested.

Contrast Media↗

Quantitative bone scintigraphy using SPECT.

A quantitative single photon emission computed tomography (SPECT) technique for measuring radiopharmaceutical uptake in humans has been applied to bone scintigraphy. The method was validated by comparing SPECT measured percent of injected [99mTc]MDP in 16 normal skulls with well counter measurements of samples of the same bones obtained at surgery. A very good correlation (r = 0.96) was found. A very good interobserver correlation (r = 0.99) and agreement were also obtained when using quantitative bone scintigraphy (QBS). Control SPECT studies of uptake in the right and left iliac bones and the right and left sacroiliac regions in each patient showed no significant differences between the contralateral sides. Studies done in seven subjects at 2 and 4 hr after the same injection and in nine subjects 4 to 8 mo later in the same subjects showed a very good agreement and no significant differences between the two measurements were found. QBS is suggested as an accurate and reproducible index for assessment of the mass of remodeling bone. Preliminary results showed differences in QBS of normal subjects at different ages. A group of 68 young patients aged 18-26 yr showed a significant higher QBS (p less than 0.001) when compared to an older group of 62 patients aged 50-85 yr. There was, however, a wide range of uptake values for the same bone in the same group, suggesting that the method should best be used for following individual patients over time.

Adult↗

Radionuclide ventriculography and central aorta pressure change in noninvasive assessment of myocardial performance.

Systolic pressure-volume diagrams were obtained noninvasively by measuring the systolic central aortic pressure with a new device and by combining the pressure measurements, thus obtained, with absolute volume measurements obtained by radionuclide ventriculography during ejection. By dividing the peak power by the time elapsed from the beginning of ejection to the peak power point, the ejection rate of change of power (ERCP) was calculated. The ability of this index to assess left ventricular function at rest and exercise was evaluated in ten healthy subjects. ERCP proved to be more sensitive than global left ventricular ejection fraction increasing fivefold from rest to exercise compared with only 20% increase in global ejection fraction. ERCP increased dramatically postexercise from 3411 +/- 2173 to 18,162 +/- 14,633 gm/sec2, median 12,750, 95% confidence interval 9700-29,600, in healthy, while in patients it increased twofold from 2637 +/- 824 to 5062 +/- 1897 gm/sec2, median 4070, 95% confidence interval 2800-7030, p less than 0.001. ERCP had an excellent discriminative power in differentiating healthy subjects from patients, having 100% sensitivity, 90% specificity, 95% accuracy, 95% positive predictive value, and 90% negative predictive value. Thus, this noninvasive index seems to have a more comprehensive ability to evaluate changes in left ventricular function and shows a promising potential for clinical applications.

Adult↗

Radionuclide assessment of bladder outlet obstruction: a noninvasive (1-step) method for measurement of voiding time, urinary flow rates and residual urine.

Radionuclide uroflowmetry was performed in 23 patients with bladder outlet obstruction and 29 controls. The parameters evaluated were voiding time, time to peak flow rate, time for 50 per cent emptying, average flow rate, peak flow rate, corrected peak flow rate [peak flow rate/(bladder volume)0.5], ejection fraction of the bladder and post-void residual urine. There was a statistically significant difference between controls and patients with bladder outflow obstruction in each parameter: voiding time 28.2 +/- 9.3 versus 49.2 +/- 26.5 seconds, time to peak flow rate 13 +/- 4.1 versus 19 +/- 12.6 seconds, time to 50 per cent emptying 5.5 +/- 2.4 versus 25.7 +/- 26.9 seconds, average flow rate 9.1 +/- 3.7 versus 4 +/- 2.3 ml. per second, peak flow rate 19.6 +/- 7.6 versus 8.8 +/- 4.1 ml. per second, corrected peak flow rate 1.22 +/- 0.32 versus 0.59 +/- 0.22, ejection fraction 95.3 +/- 3.5 versus 79.7 +/- 17.6, and residual urine 13.1 +/- 13.5 versus 74.1 +/- 135 ml., respectively. The corrected peak flow rate showed the best separation between controls and patients with obstruction. Of the controls 93 per cent had a corrected peak flow rate of 0.87 or greater compared to only 13 per cent of the patients with obstruction. This method involves a single noninvasive procedure that enables determination of voiding parameters related to urinary volume, flow and time, and it avoids the extra examination needed to determine the residual urine.

Adolescent↗

Radionuclide measurement of bladder emptying rate. Simultaneous comparison with urinary flow rate obtained by uroflowmetry.

Mean and peak bladder emptying rates were measured by a radionuclide method using a gamma camera and Tc-99m DTPA and were compared with average and maximum urinary flow rates obtained by a uroflowmeter in 24 simultaneous measurements. A good correlation was found between the two methods. Average urinary flow rate correlates better with mean bladder emptying rate (r = 0.96, y = 1.04X + 0.14, s.e.e. = 1.2) than maximum urinary flow rate with peak bladder emptying rate (r = 0.83, y = 0.78X + 4.5, s.e.e. = 4.2). The results suggest that the radionuclide method can be used to measure the urinary flow rate, and has the advantage of establishing the postvoid residual urine.

Adult↗

SPECT quantitation of cobalt-57 bleomycin delivery to human brain tumors.

A newly developed and validated noninvasive quantitative SPECT method was used to measure the in vivo uptake of [57Co]bleomycin (Co-bleo) in 13 human brain tumors and the uptake of [99mTc]glucoheptonate (GH) in 23 brain tumors. Significant differences in tumor uptake were found. The tumor concentration over time, the tumor to blood radio at 30 min and the tumor cumulative concentration of radioactivity showed marked differences even between tumors with the same histology. Only a weak correlation was found between tumor concentration of Co-bleo and of GH. Therefore a simple imaging agent such as GH cannot, at the present time, serve as an indicator of individual tumor uptake and further experience with other agents is still necessary. Contrary to the generally held view, no correlation was found between the concentration of drug in the blood and its tumor concentration. It is suggested therefore that the level of a drug in the blood cannot be used as a criterion of the amount that will penetrate the tumor. Direct SPECT measurement of the concentration of the drug in the tumor itself should be performed. The bioavailability of a drug is critical in order for it to exert it tumoricidal effect. The results, showing marked differences in uptake between brain tumors, suggest that before chemotherapy is administered, uptake of the chemotherapeutic drug in the individual tumor to be treated should be assessed and comparisons should be made between the uptake of a series of drugs to determine which drug would be most efficacious on the basis of its uptake as well as its tumor cell killing potential.

Biological Availability↗

Normal and abnormal single photon emission computed tomography of the skull: comparison with planar scintigraphy.

Using a rotating gamma camera the normal single photon emission computed tomography (SPECT) anatomy of the skull was defined in eight subjects. The value of SPECT as compared with planar scintigraphy was assessed in 34 patients with known or suspected disease of the skull. Seven patients had normal planar scintigraphy and SPECT. In 12 of 27 patients with bone involvement SPECT and planar scintigraphy showed essentially the same findings. In 15 patients SPECT was superior to planar scintigraphy. In three of these patients SPECT detected lesions while planar scan was normal. In the other 12 patients SPECT showed better anatomic localization and defined the full extent of the lesion. This was most obvious in patients with involvement of sphenoid, petrous, clivus, maxilla, and zygomatic bones. Our findings confirm the potential of SPECT to detect lesions in deep bones that are overlapped by superficial bony structures that cannot be visualized clearly with planar scintigraphy.

Bone Diseases↗

Radionuclide angiography of azygos continuation of inferior vena cava in left atrial isomerism (polysplenia syndrome).

Interruption of the inferior vena cava with azygos continuation is present in at least 65% of the patients suffering from left atrial isomerism (polysplenia syndrome). First-pass radionuclide angiography using a peripheral vein of the foot correctly diagnosed interruption of the inferior vena cava in seven patients. Four had azygos continuation to the right superior vena cava and in three it was to the left superior vena cava. In all the patients, cardiac catheterization confirmed the diagnosis. Four underwent surgical correction (or palliation), three are waiting for an operation. Radionuclide angiography is a simple outpatient procedure and useful in the clinical diagnosis of this syndrome.

Abnormalities, Multiple↗

Osteomyelitis and soft-tissue infection: differential diagnosis with 24 hour/4 hour ratio of Tc-99m MDP uptake.

The lesion-to-nonlesion 24 hour/4 hour ratio of technetium-99m methylene diphosphonate (MDP) uptake was used to distinguish osteomyelitis from increased bone uptake caused by adjacent soft-tissue infection. In a prospective study, this ratio was measured in 38 patients with 41 sites of increased uptake that were suspected to be osteomyelitis. The mean ratio was 1.18 +/- 0.18 in patients with proved osteomyelitis, which was significantly higher (P less than .001) than that in patients with increased uptake resulting from soft-tissue infection (0.98 +/- 0.05). On the basis of a receiver operating characteristic curve, a ratio of 1.06 was selected as the cutoff for differentiating osteomyelitis from soft-tissue infection. This method resulted in a sensitivity of 82%, a specificity of 92%, and an accuracy of 85%, and it appears to be more reliable than three- and four-phase scintigraphy, which are subjective and nonquantitative techniques.

Adolescent↗

In vivo quantitation using SPECT of radiopharmaceutical uptake by human meningiomas.

A single photon emission computed tomographic method was designed for the measurement of radiopharmaceutical uptake in brain tumors. Results of phantom studies showed a correlation coefficient of .99 when measured volume was compared with actual volume. The correlation coefficient for measured radioactivity concentration compared with the actual concentration was .97. In 13 meningiomas the correlation between in vivo SPECT measurements of uptake and in vitro measurements in samples of the same tumors removed surgically was .84; when two tumors that contained regions of necrosis and fibrosis were excluded it was .93. This method can be used for in vivo quantitative assessment of pharmacokinetics of labeled drug uptake in human brain tumors.

Evaluation Studies as Topic↗

Human lung tumors: SPECT quantitation of differences in Co-57 bleomycin uptake.

A newly developed single photon emission computed tomography (SPECT) method was used to measure noninvasively the concentration of labeled drugs in human lung tumors. The validity of the method was established by the high correlation (r = .92) between in vivo SPECT measurement of the concentration of glucoheptonate labeled with technetium-99m and in vitro measurement of the concentration of the drug in specimens of nine of the same tumors obtained at surgery. The in vivo concentration of intravenously injected bleomycin labeled with cobalt-57 was measured over time in 14 human lung tumors. Significant differences were found in the uptake of bleomycin by the tumors, even those with the same histologic characteristics, when the concentration over time, the tumor/blood ratio at 30 minutes, and the tumor cumulative concentration were measured in vivo. Since the drug concentration in the blood was not related to the concentration in the tumor (r = .54), uptake of chemotherapeutic drugs should be measured in each patient individually.

Adenocarcinoma↗