Increased renal retention of 99mTc-methylene diphosphonate after nephron-sparing surgery.
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Nephron-sparing surgery has become established as an effective treatment for localized renal cell carcinoma when preservation of renal function is necessary. The surgery usually requires temporary renal artery occlusion and may induce ischemic renal damage. In this study, we retrospectively evaluated renal activity on bone scintigraphy after nephron-sparing surgery. METHODS: Eleven patients who underwent nephron-sparing surgery for renal cell carcinoma and had a normal contralateral kidney were studied. A total of 12 bone scintigraphy images with 99mTc-labeled methylene diphosphonate were obtained within 1 y after surgery in these patients to assess skeletal metastasis. Activity in the spared renal parenchyma was compared visually with that in the contralateral normal kidney. RESULTS: The tumor was successfully resected in every patient, and no clinically significant complications occurred. Activity in the spared renal parenchyma was elevated in six of seven examinations performed within 21 d after surgery. In three examinations, the increase in renal activity was heterogeneous, being relatively prominent near the surgical margin. Increased renal activity was not observed on five examinations performed 3 mo or more after surgery. CONCLUSION: Renal retention of bone-seeking agents is elevated in the early period after nephron-sparing surgery, probably as a result of ischemic insult during the surgical procedure. Bone scintigraphy may aid in evaluating the presence and degree of ischemic damage of the spared renal parenchyma. (+info)
Prospective validation of single plasma sample 99mTc-ethylenedicysteine clearance in adults.
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99mTc-L,L-ethylene, L, dicysteine (EC) clearance shows strong correlation with orthoiodohippurate clearance, and it is possible to estimate effective renal plasma flow from 99mTc-EC clearance. In routine clinical studies, it is practical to use the one or two plasma sample method instead of multiple plasma samples for clearance determination. A single-sample technique was developed for 99mTc-EC, and a regression formula was generated. A prospective study tested the validity of this regression formula. METHODS: The study population was composed of 26 patients with a wide range of renal function. Multiple plasma sample 99mTc-EC clearances were calculated from all patients using the open two-compartment model. Single plasma sample clearances were also determined from the 54-min plasma sample using the regression formula published previously. RESULTS: The multiple-sample plasma clearance of 99mTc-EC ranged from 46 to 668 mL/min with a mean of 300.76 +/- 150.73 mL/min. The clearances obtained from the 54-min plasma sample ranged from 49 to 699 mL/min, with a mean of 297.39 +/- 152.23 mL/min. There was an excellent correlation between the clearances obtained by the two techniques (r = 0.99, slope = 0.9911). The standard error of estimation was found to be 25.9 mL/min. CONCLUSION: This study suggests that 99mTc-EC clearance can be estimated from 54-min plasma samples with an acceptable error of estimation for most routine clinical studies. (+info)
Attenuation compensation in 99mTc SPECT brain imaging: a comparison of the use of attenuation maps derived from transmission versus emission data in normal scans.
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Brain SPECT imaging using 99mTc lipophilic tracers such as hexamethyl propyleneamine oxime (HMPAO) attempts to estimate cerebral, cerebellar and subcortical perfusion by assessing the relative amount of tracer uptake among these regions. Most commonly, comparison is made with cerebellar activity. Because the assessment of relative tracer uptake may be rendered inaccurate by photon attenuation by the nonuniform attenuation properties of the head, brain SPECT reconstructions have been compared using attenuation correction (AC) with various methods for estimating the attenuation map. METHODS: Patients underwent 99mTc-HMPAO brain SPECT with transmission line source AC hardware. In addition to the emission dataset, emission downscatter and transmission datasets were acquired. Iterative reconstructions using three different attenuation maps were investigated. These included: (a) that obtained from transmission imaging, (b) that obtained from segmentation of a reconstruction from a lower energy Compton scatter window and (c) a slice-independent, uniform, elliptical attenuation map. No AC was also compared. RESULTS: Count profiles in patients having brain perfusion SPECT scans showed a significant difference in region count estimates in the brain depending on whether AC is used as well as on the attenuation map used. Scatter-based AC is able to provide external contour detection and attenuation compensation based on that contour, whereas transmission-based AC provides external contour detection as well as internal, nonuniform attenuation estimation and AC. If one considers transmission AC to be the clinical "gold standard," non-attenuation-corrected as well as fixed-ellipsoid, uniform attenuation-corrected studies provided unreliable regional estimates of tracer activity. CONCLUSION: This study shows the significant difference in clinical brain SPECT count profiles depending on how and whether there is compensation for attenuation. Based on prior studies validating the improved quantitative accuracy of SPECT using transmission-based AC, this study suggests that clinical 99mTc brain perfusion SPECT would benefit from and, in situations demanding rigorous quantitative assessment, requires transmission-based AC. Estimating attenuation maps with scatter-based methods was the next most accurate (clinical) method tested and can be used if and when transmission imaging cannot be used. (+info)
Biodistribution, radiation dosimetry and pharmacokinetics of 111In-antimyosin in idiopathic inflammatory myopathies.
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In view of the established role of 111In-antimyosin in the detection of heart muscle pathology, radiation dose estimates were made for this substance. Biodistribution and biokinetic data were obtained from our studies, which failed to show abnormal uptake of 111In-antimyosin in localized sites of skeletal muscle involvement in patients with idiopathic inflammatory myopathies. METHODS: After intravenous administration of 74 MBq (2 mCi) 111In-antimyosin, gamma camera scintigraphy was performed in 12 adult patients with inflammatory muscle disease and in 2 control patients. Six whole-body scans were performed over 72 h, and uptake of 111In-antimyosin in organs was quantified using an attenuation-corrected conjugate counting method. Residence times in source organs were used with MIRDOSE software to obtain radiation dose estimates. Pharmacokinetic parameters were derived from serial whole-blood and plasma 111In concentrations. RESULTS: The tracer cleared slowly from the circulation, and highest organ uptakes were found in the marrow and liver; kidneys showed the highest concentrations. Uptake was also evident in spleen, the facial image and male genitalia. CONCLUSION: For a typical administered activity of 74 MBq 111In-antimyosin, the kidneys receive the highest dose (58 mSv), and the effective dose is 11 mSv. Radioactivity was cleared from plasma at an average rate of 136 mL/h, and the mean steady-state distribution was approximately 5 L plasma. (+info)
MIRD Pamphlet No. 15: Radionuclide S values in a revised dosimetric model of the adult head and brain. Medical Internal Radiation Dose.
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Current dosimetric models of the brain and head lack the anatomic detail needed to provide the physical data necessary for suborgan brain dosimetry. During the last decade, several new radiopharmaceuticals have been introduced for brain imaging. The marked differences of these tracers in tissue specificity within the brain and their increasing use for diagnostic studies support the need for a more anthropomorphic model of the human brain and head for use in estimating regional absorbed dose within the brain and its adjacent structures. METHODS: A new brain model has been developed that includes eight subregions: the caudate nuclei, the cerebellum, the cerebral cortex, the lateral ventricles, the lentiform nuclei, the thalami, the third ventricle and the white matter. This brain model is incorporated within a total revision of the head model presented in MIRD Pamphlet No. 5 Revised. Modifications include the addition of the eyes, the teeth, the mandible, an upper facial region, a neck region and the cerebrospinal fluid within both the cranial and spinal regions. RESULTS: Absorbed fractions of energy for photon and electron sources located in 14 source regions within the new model were calculated using the EGS4 Monte Carlo radiation transport code for particles in the energy range 10 keV-4 MeV. These absorbed fractions were then used along with radionuclide decay data to generate S values for 24 radionuclides that are used in clinical or investigational studies of the brain, 12 radionuclides that localize within the cranium and spinal skeleton and 12 radionuclides that selectively localize in the thyroid gland. CONCLUSION: A substantial revision to the dosimetric model of the adult head and brain originally published in MIRD Pamphlet No. 5 Revised is presented. This revision supports suborgan brain dosimetry for a variety of radiopharmaceuticals used in neuroimaging. Dose calculations for the neuroimaging agent 1231-tropane provide an example of the new model and yield mean brain doses that are consistent with published values. However, the absorbed dose to subregions within the brain such as the caudate and lentiform nuclei may exceed the average brain dose by a factor of up to 5. (+info)
Detection of focal myeloma lesions by technetium-99m-sestaMIBI scintigraphy.
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BACKGROUND AND OBJECTIVE: The tracer tachnetium-99m-2-methoxy-isobutyl-isonitrile (Tc99m-sestaMIBI) has recently been shown to concentrate in some neoplastic tissues, including myeloma. We investigated the diagnostic capacity and limits of this procedure in tracing focal myeloma lesions, and compared them with those of conventional radiological procedures (Xr). DESIGN AND METHODS: We studied 55 patients suffering from multiple myeloma (MM) or solitary plasmacytoma in different stages and clinical conditions, or from monoclonal gammopathy of undefined significance (MGUS), by whole body scans obtained 10 minutes after injection of 555 MBq of Tc99m-sestaMIBI. Scans were defined as normal (physiological uptake only), diffuse (presence of bone marrow uptake), or focal (localized areas of uptake), and were compared to conventional skeletal Xr. RESULTS: Thirty patients showed no focal areas of Tc99m-sestaMIBI uptake; this group consisted of 5 patients with MGUS, 6 with MM in stage IA and 2 in stage IIA, 11 patients studied after effective chemotherapy and 6 in early relapse. Twenty-five patients showed one or more spots of focal uptake: all of them had active disease (untreated, resistant or relapsing MM). In the setting of tracing focal lesions, Tc99m-sestaMIBI scans were concordant with the radiological examination in 38 patients and discordant in 17. Among the latter, in 4 cases Tc99m-sestaMIBI revealed focal lesions not detected by Xr, and in 13 cases lytic areas detected by Xr did not show Tc99m-sestaMIBI uptake. INTERPRETATION AND CONCLUSIONS: In untreated patients, the number of lesions revealed by Tc99m-sestaMIBI was comparable to that shown by Xr, while in pretreated patients Tc99m-sestaMIBI traced a number of lesions lower than that detected by Xr. The reason for this discrepancy is that Tc99m-sestaMIBI traces only active lesions. Tc99m-sestaMIBI limitations in identifying focal lesions may derive from the dimension of the smallest traceable lesion (about one centimeter), and from the possibility that focal plasma cell localizations in collapsed bone may not be visualized due to inadequate vascularization. Tc99m-sestaMIBI scintigraphy is an interesting tool for diagnosing, staging and following up focal myeloma lesions, in the bone as well as in soft tissues. It is more specific than conventional Xr in identifying sites of active disease. (+info)
Early and delayed MR and PET changes after selective temporomesial radiosurgery in mesial temporal lobe epilepsy.
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We report a patient with medically refractory mesial temporal lobe epilepsy treated by gamma knife radiosurgery. In lieu of a microsurgical procedure, an entorhinoamygdalohippocampectomy was performed with a gamma knife and low marginal doses (25 Gy). The clinical and imaging studies, including CT, MR imaging, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), and long-term follow-up MR examinations, are reported. The patient has been seizure-free since the day of treatment, with no clinical complications. MR studies accurately depicted the effect on the target structures and the transient secondary changes around them. FDG-PET scans showed decreased metabolism after gamma knife surgery throughout the anteromesial part of the epileptogenic temporal lobe. This metabolic decrease was reversible in the lateral temporal cortex. Our case suggests that gamma knife surgery is a promising tool for use as a minimally invasive approach to the treatment of epilepsy. (+info)
67Cu-versus 131I-labeled Lym-1 antibody: comparative pharmacokinetics and dosimetry in patients with non-Hodgkin's lymphoma.
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Antilymphoma mouse monoclonal antibody (MoAb) Lym-1, labeled with 67Cu or 131I, has demonstrated promising results in radioimmunotherapy (RIT) for lymphoma. Although 131I has played a central role in RIT thus far, some properties of 67Cu are preferable. A subset of our patients received both 67Cu- and 131I-labeled Lym-1, allowing a comparative evaluation of the two radiopharmaceuticals administered to a matched population of patients. Four patients with B-lymphocytic non-Hodgkin's lymphoma that had progressed despite standard therapy entered trials of 67Cu- and 131I-labeled Lym-1, which were injected 3-26 days apart. Lym-1 was conjugated to 6-[p-(bromoacetamido)benzyl]-1,4,7,11-tetraazacyclotetradecane-N,N ',N",N'"-tetraacetic acid (BAT) via 2-iminothiolane (2IT) and radiolabeled with 67Cu to prepare 67Cu-2IT-BAT-Lym-1; 131I-Lym-1 was preparred by the chloramine-T reaction. Planar imaging was used to quantitate 67Cu-2IT-BAT-Lym-1 or 131I-Lym-1 in organs and tumors daily for 3 days or longer. 67Cu-2IT-BAT-Lym-1 exhibited higher peak concentration in 92% (12 of 13) of tumors and a longer biological half-time in every tumor than 131I-Lym-1. The mean tumor concentration (%ID/g) of 67Cu-2IT-BAT-Lym-1 was 1.7, 2.2, and 2.8 times that of 131I-Lym-1 at 0, 24, and 48 h after injection, respectively. The mean biological half-times of 67Cu-2IT-BAT-Lym-1 and 131I-Lym-1 in tumor were 8.8 and 2.3 days, respectively. Consequently, the mean tumor radiation dose delivered by 67Cu-2IT-BAT-Lym-1 was twice that of 131I-Lym-1, 2.8 (range 0.8-6.7), and 1.4 (range 0.4-35) Gy/GBq, respectively. 67Cu-2IT-BAT-Lym-1 delivered a lower marrow radiation dose than 131I-Lym-1; hence, the tumor:marrow therapeutic indices were 29 and 9.7, respectively. Radiation doses from 67Cu-2IT-BAT-Lym-1 and 131I-Lym-1 to normal tissues were similar except for liver, which received a higher dose from 67Cu-2IT-BAT-Lym-1. Images obtained with 67Cu-2IT-BAT-Lym-1 were superior. Radiation dosimetry data for 67Cu-2IT-BAT-Lym-1 and 131I-Lym-1 agreed with corresponding data from the larger populations of patients from which the matched population for the current study was drawn. In conclusion, 67Cu-2IT-BAT-Lym-1 given to non-Hodgkin's lymphoma patients in close temporal proximity to 131I-Lym-1 exhibited greater uptake and longer retention in tumor, resulting in higher radiation dose and therapeutic index than 131I-Lym-1. These as well as other factors suggest that 67Cu-2IT-BAT-Lym-1 may be superior to 131I-Lym-1 for RIT. (+info)