Is corticosteroid coinjection necessary for radiosynoviorthesis of patients with hemophilia?

PURPOSE: Radiation synovectomy is frequently combined with intraarticular corticosteroid injection in the treatment of rheumatoid arthritis to reduce local inflammation and lymphatic clearance of radiocolloid. However, this practice is not universally accepted because corticosteroids have local and systemic toxicity such as osteonecrosis and cartilage damage and whether simultaneous corticosteroid injection together with radiocolloids is necessary in other forms of chronic synovitis like patients with hemophilia remains to be determined. MATERIALS AND METHODS: In this study, we performed radiosynoviorthesis in 14 joints of 12 patients with hemophilia with chronic knee synovitis without corticosteroid coadministration and measured radiocolloid leakage from the joint space. Five mCi Y-90 radiocolloid was injected under local anesthesia and the needle was flushed with additional lidocaine injection instead of corticosteroid. The joint was then manipulated through a full range of extension and flexion to distribute the particles homogeneously throughout the joint space. The joint was then splinted for 48 hours to minimize leakage from the joint space. After the immobilization period, radiocolloid leakage was evaluated using a gamma camera with a 20% window centered over the maximum Bremsstrahlung photopeak of Y-90. Regions of interest were drawn to the injection site on the knee joint and to the ipsilateral inguinal lymph node area. Leakage of radiocolloid was calculated by dividing the background-corrected counts/pixel at the inguinal region by the counts/pixel at the injection site. RESULTS: One of 12 patients who had knee arthroplasty was previously found to have a high amount of leakage. In this patient, 70% of radiocolloid at the injection site drained into the pelvic lymph nodes. In the remaining 11 patients, no lymph nodes were visualized in the groin area and the measured average leakage for these patients was 2.3% (range, 0-13). CONCLUSION: We concluded that in cases of appropriate particle size and strict immobilization of knee joints, leakage of radiocolloid was minimal and steroid coinjection might not be necessary for radiosynoviorthesis of patients with hemophilia with chronic knee synovitis.     

90Y bremsstrahlung emission computed tomography using gamma cameras

Objective  This study demonstrates images obtained by ⁹⁰Y bremsstrahlung emission computed tomography (BECT), and characterizes the system performance of gamma cameras. Methods   ⁹⁰Y BECT images of phantoms were acquired using a gamma camera equipped with a medium energy general purpose parallel-hole collimator. Three energy window widths of 50% (57–94 keV) centered at 75 keV, 30% (102–138 keV) at 120 keV, and 50% (139–232 keV) at 185 keV were set on a ⁹⁰Y bremsstrahlung spectrum. The images obtained with three energy windows were reconstructed using filtered back projection (FBP) and ordered subsets expectation maximization (OSEM) methods. The images of the sum window were obtained by fusing the images of the 75, 120, and 185 keV windows. Results  The OSEM method improved the full width at half maximum by 20% and the standard deviation by 9% compared with the FBP method. BECT displayed ⁹⁰Y biodistribution and quantified ⁹⁰Y activity. BECT images obtained with OSEM method using the 120 keV window showed the highest resolution and lowest uncertainty. The sum window showed the highest sensitivity, while its resolution was 10% inferior to that of the 120 keV window. One whole-body image can be taken over 100 min using the sum window. An absorber to cover the body surface reduced background by 30%. Conclusions   ⁹⁰Y BECT imaging can be used for patient assessment without modifying current treatment procedures.     

Production of large quantities of 90Y by ion-exchange chromatography using an organic resin and a chelating agent

The performance of a system composed of an organic cation exchanger (Dowex 50Wx8) and a chelating agent (EDTA) previously described for the successful production of (90)Y via a (90)Sr/(90)Y generator is assessed under dynamic conditions. In an attempt to overcome the established limitation of ion-exchange resins for the separation of subcurie quantities of activity, (90)Y is repeatedly isolated from an 11.8-GBq (320 mCi) (90)Sr cow using a three-column tandem arrangement. The high recovery and radionuclidic purity obtained for (90)Y and the parameters of the separation (time, eluant concentration, pH and flow rate range) strongly suggest that Ci quantities of (90)Y can be handled satisfactorily by the ion-exchange method. No replacement or treatment of the cow, low waste generation and (90)Sr losses less than 0.1% after each run were observed during the present study which, in combination with the low cost of this resin, may result in an attractive alternate method for the production of large quantities of (90)Y.     

Rapid determination of Sr impurities in freshly “generator eluted” Y for radiopharmaceutical preparation

⁹⁰Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t_1/2=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that ⁹⁰Y is available conveniently and inexpensively from a radionuclide “generator” by decay of its parent, ⁹⁰Sr. Nevertheless, current and planned clinical applications with [⁹⁰Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an “in-house” generator or as a fast QC method for analysis of ⁹⁰Y solutions.In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO₃ eluate: in this fraction the concentration of ⁹⁰Sr must be smaller than 10⁻⁵% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of ⁹⁰Y in all the fractions containing “only” radio-Sr: ⁹⁰Y should not be present in these eluates. After the collection of β⁻ and γ spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.     

Bioevaluation of 90Y-labeled particles in animal model of arthritis

Objective  The aim of the present study was to evaluate the behaviour of ⁹⁰Y-labeled particles when injected into an arthritic knee joint of Wistar rats with severe inflammation induced using Complete Freund’s Adjuvant (CFA). Methods   ⁹⁰Y-ferric hydroxide macroaggregates (⁹⁰Y-FHMA), ⁹⁰Y-hydroxyapatite (⁹⁰Y-HA) and ⁹⁰Y-phosphate particles (⁹⁰YPO₄) were prepared, subjected to quality control analyses and in vitro stability studies. Biodistribution studies were carried out by intra-articular injection into knee joints of Wistar rats induced with chronic inflammatory arthritis using CFA and by monitoring the radioactivity for retention and leakage. Results  All the three preparations exhibited ~99% localization in knee joints even at 24 h p.i. with very small amounts observed in the liver and lungs, possibly due to leakage of the radiolabeled particles from the inflamed knee joint. Absence of any radioactivity in the femur indicated the in vivo stability of the particle preparations. Conclusions  The biodistribution patterns were very similar in the normal and arthritic rats and were associated with negligible leakage (up to 24 h) from the knee joint indicating the potential of all the ⁹⁰Y-radiolabeled preparations reported here, for use in radiation synoviorthesis.     

Radiation protection in radionuclide therapies with 90Y-conjugates: risks and safety

Purpose The widespread interest in ⁹⁰Y internal radionuclide treatments has drawn attention to the issue of radiation protection for staff. Our aim in this study was to identify personnel at risk and to validate the protection devices used.Methods ⁹⁰Y-MoAb (Zevalin, 15 cases, 1.1 GBq/patient) and ⁹⁰Y-peptide (⁹⁰Y-DOTATOC) systemic (i.v., 50 cases, 3.0 GBq/patient) and locoregional (l.r., 50 cases, 0.4 GBq/patient) treatments were considered. Radiolabelling was carried out in a dedicated hot cell. Tele-tongs, shielded (PMMA: polymethylmethacrylate) syringes/vials and an automatic dose fractionating system were used. Operators wore anti-X-ray and anti-contamination gloves, with TLD dosimeters placed over the fingertips. For i.v. administration, activity was administered by a dedicated system; for l.r. administration, during activity infusion in the brain cavity, tongs were used and TLDs were placed over the fingertips. The air kerma-rate was measured around the patients.Results The use of devices provided a 75% dose reduction, with mean fingertip doses of 2.9 mGy (i.v. MoAbs), 0.6 mGy (i.v. peptides)/radiolabelling procedure and 0.5 mGy/l.r. administration. The mean effective dose to personnel was 5 μSv/patient. The air kerma-rate around the patients administered i.v. ⁹⁰Y-peptides were 3.5 (1 h) and 1.0 (48 h) μGy/h at 1 m. Patient hospitalisation of 6 h (l.r.)/48 h (i.v.) guaranteed that the recommended limits of 3 mSv/year to family members and 0.3 mSv/year to the general population (Council Directive 97/43/Euratom) were respected.Conclusions When specific procedures are adopted, a substantial improvement in ⁹⁰Y manipulation is attainable, reducing doses and increasing safety. For the widespread clinical use of ⁹⁰Y-conjugates, a completely automatic labelling procedure is desirable.     

Sequential Use of 90Y Microspheres Radioembolization and 177Lu-Dotatate in Pluri-Metastatic Neuroendocrine Tumors: A Case Report

⁹⁰Y radioembolization and peptide-receptor radionuclide therapy (PRRT) with¹⁷⁷Lu-DOTATATE are both effective treatments for patients with inoperable neuroendocrine metastatic tumors (NET). We report the case of a 72-year-old man with severe functional syndrome due to a metastatic NET. ⁶⁸Ga-DOTATOC positron-emission tomography (PET) revealed high somatostatin receptor expression in a gross liver metastasis, in one abdominal lymph node and in several skeletal lesions. The patient underwent liver radioembolization with ⁹⁰Y-resin microspheres followed by four cycles of PRRT with¹⁷⁷Lu-DOTATATE. After 3 months, a complete remission of the functional syndrome was observed. ⁶⁸Ga-DOTATOC PET demonstrated a complete response for skeletal and lymph nodal lesions with a residual bulky mass in the liver. Therefore a further ⁹⁰Y radioembolization was performed as consolidation treatment for the hepatic lesion. Six months after these combined treatments, ⁶⁸Ga-DOTATOC PET demonstrated complete metabolic response in liver and stable extrahepatic lesions. No significant long-term adverse reactions were registered. To our knowledge, the sequential use of ⁹⁰Y radiembolization before and after PRRT in a liver-dominant advanced NET has not been reported in the literature and this case suggests that these combined treatments can be safe and effective.     

90Sr-90Y对人良性前列腺增生细胞增殖与凋亡影响的研究

目的探讨放射性核素     

Radio-synovectomy in chronic synovitis of the knee joint in patients with rheumatoid arthritis

The influence of intra-articular (i.a.) colloidal 198Au (5 mCi) or 90Y-silicate (5 mCi) on synovitis of the knee joint in patients older than 45 years with rheumatoid arthritis (RA), who had been treated since 1970 in our hospital, was investigated. Of the 89 knee joints of 77 patients studied, 65 had no or minimal radiological abnormalities of the knee joint treated (group I), whereas 24 patients had moderate to severe changes (group II). Before and at regular intervals after radio-synovectomy the clinical response was scored using pain, hydrops and warmth as parameters. The results indicated that 1 year after treatment the percentage of knee joints with a favourable response was greater in group I than in group II (58% versus 25%, P = 0.001). This difference was still present 3 years after treatment. Clinical response showed no correlation with initial inflammatory activity as measured by 99mTc-pertechnetate uptake measurements. However, in group I, those patients with an ESR below 60 mm/h, measured just before radio-synovectomy, more often had a favourable response than those with an ESR in excess of 60 mm/h (P = 0.01). No or only slight complications of radio-synovectomy were noted, whereas leakage of radioactivity from the knee joints was minimal. It is concluded that radio-synovectomy is an effective and safe procedure in those patients with rheumatoid synovitis of the knee joint without the presence of significant radiological damage and the absence of active systemic disease.     

Optimum energy window setting on Hg-201 x-rays photopeak for effective Tl-201 imaging

For more effective Tl-201 imaging, the location and width of the energy window set on the Hg-201 x-rays photopeak was investigated using Monte Carlo simulation and phantom experiments. We calculated energy spectra and investigated the amount of primary and scattered photons within various energy windows set on the x-rays photopeak. The energy resolution (ER) at 71 keV (the peak of the x-rays photopeak) was changed to 10%, 12%, 14% and 16%. The relationships between the energy window and the primary counts rate or the scatter fraction (= scattered counts/primary counts, SF) were obtained. By compromise between the primary counts rate and the SF for ER = 12%, the optimum energy window was determined as a wider off-peak window, 77 keV ± 14.3% (66–88 keV). This off-peak window increased the primary counts rate by 12.5% and decreased the SF by ~17% as compared with the conventional on-peak energy window (71 keV ± 10%, 64–78 keV). When this off-peak widow acquisition was compared with the conventional on-peak window one on a gamma camera, planar and SPECT images using the off-peak widow clearly showed superior results qualitatively and quantitatively.     

Comparison of calibration results for an extrapolation chamber obtained with different Sr+Y secondary standard sources

Two secondary standard systems of beta radiation were used to calibrate a PTW extrapolation chamber Model 23391. Three ⁹⁰Sr+⁹⁰Y sources of different activities were used in this calibration procedure. Medium-term stability of the response of the chamber was also studied. The calibration was performed with and without field-flattening filters. The relative standard deviation of the obtained calibration factors was 8.3% for the aluminum collecting electrode and 4.1% for the graphite collecting electrode.     

Quantitative 99Tcm-HMPAO white blood cells and 67Ga scanning in rheumatoid arthritis

This investigation assessed 99Tcm-HMPAO white blood cell (Tc-WBC) and 67Ga knee uptake indices before and after 90Y treatment in patients with intractable rheumatoid arthritis (RA) and correlated the uptake indices with the clinical score. Sixteen knee joints with RA were treated with intra-articular injection of 185 MBq of 90Y-silicate colloid (Amersham) flushed with 50 mg of hydrocortisone. Clinical score, quantitative 67Ga and Tc-WBC knee uptake indices were obtained before and three weeks after treatment. Our results showed that 9/16 (56%) had a good response and 7/16 (44%) had a poor response to 90Y injection. There was poor correlation between clinical improvement and changes in 67Ga and Tc-WBC knee uptake indices (r = 0.46 and 0.14, respectively). The correlation coefficient between changes in 67Ga and Tc-WBC knee uptake indices was 0.29.     

Quantification of bone scintigraphy as an objective method in the follow-up of radioisotopic synoviorthesis

This work tries to provide the clinicians an objective tool that can contribute to the assessment of the results of radioisotopic synoviorthesis (RS). This study aims to assess the value of the quantification of bone scintigraphy in blood pool and late phase of the affected joints treated with 90Y silicate, in order to observe the clinical improvement experienced by most of these patients. A total of 69 bone scintigraphies (BS) in blood pool and late phase have been quantified. They belonged to 23 patients who were treated with RS with 90Y. The first scintigraphy study was performed before the treatment, the second and the third ones were performed 2 and 6 months after treatment. In each BS we quantified the index: counts per pixel of healthy / affected joint. We also have calculated the fraction in the late phase: counts per pixel of healthy bone / counts per pixel of affected and healthy joint. For the comparative statistical analysis of the results we used the Student's t test. We considered statistical significance when p < 0.05. All the patients presented clinical improvement. If we compare the index obtained in BS 2 months after treatment and pre-treatment we find statistical significance (p < 0.05) in the increase of index in the anterior view and late phase. If we compare the index obtained in BS 6 month after treatment and pre-treatment, we find a statistically significant increase in the anterior (p < 0.01) and posterior (p < 0.05) view of the blood pool phase and the anterior view of late phase (p < 0.01). The fraction counts per pixel of healthy bone / counts per pixel of affected and healthy joint did not present a significant increase in any BS control (2 and 6 months). We recommend quantification using the index (counts per pixel healthy / affected joint ) proposed in this work, because it is easy to perform, cheap and reliable in the follow-up of patients treated with RS.     

90Y microsphere treatment of unresectable liver metastases: changes in 18F-FDG uptake and tumour size on PET/CT

Purpose The intra-arterial administration of ⁹⁰Y microspheres is a new palliative treatment option for unresectable liver metastases. The aim of this study was to quantitatively assess changes in FDG uptake and tumour size following ⁹⁰Y microsphere treatment (SIR-Spheres) using ¹⁸F-fluorodeoxyglucose (FDG) PET/CT imaging.Methods Five patients with unresectable liver metastases who had failed multiple prior chemotherapy regimens received seven ⁹⁰Y microsphere treatments to a single liver lobe. All patients underwent a baseline PET/CT scan prior to treatment, as well as up to four follow-up PET/CT scans. The tumour area of 30 liver metastases was measured on CT and the FDG uptake was semiquantitatively assessed by calculation of standardised uptake values (SUVs). A total of 18 FDG-PET/CT scans were performed.Results The SUVs in the 30 treated liver metastases decreased from 6.5±2.3 at baseline to 4.2±1.8 after the first follow-up PET/CT scan (p=0.001). In contrast, the SUVs of untreated metastases increased slightly from 7.2±2.3 to 8.0±0.8. There was no difference in FDG uptake in treated versus untreated normal liver tissue. Using a previously defined threshold of 20% decrease in SUV from baseline to determine response, 20 out of 30 liver metastases were considered to have responded at the first follow-up PET/CT scan approximately 1 month after treatment. In these metastases, the SUV decreased by 47±12%, compared with a slight increase by 5.9±19% in ten non-responding metastases (p=0.0001). The changes in tumour size did not correlate with changes in FDG uptake. On the first follow-up PET/CT scan, the tumour area on CT increased by 3.1±57% in treated metastases compared with 23.3±32% in untreated metastases. A wide range of post-treatment changes of target lesions was observed on CT, including an increase in the size of hypodense lesions, necrotic features and complete resolution of CT abnormalities.Conclusion The metabolic information obtained from FDG-PET/CT seems to provide a more accurate and earlier assessment of therapy response following ⁹⁰Y microsphere treatment than does the anatomical CT information.     

SPECT using Bremsstrahlung to quantify 90Y uptake in Baker's cysts: its application in radiation synovectomy of the knee

The use of SPECT with Bremsstrahlung radiation has been investigated in studies on patients undergoing 90Y therapy for persistent synovitis of the knee. In particular, its value in the estimation of 90Y uptake into Baker's cysts was assessed and, to this end, realistic 'knee phantoms' were employed in order to calibrate for cysts of different size. Problems associated with the measurement of the extensive Bremsstrahlung spectrum and the estimation of cyst volume have been discussed. It is shown that, although the apparent volume of a cyst is markedly dependent on the chosen count rate threshold, volumes greater than about 30 ml can be estimated with reasonable accuracy using a threshold of 50%. The uptake of 90Y in cysts, measured on 3 occasions within the first 2 days in 10 patients, showed wide variation (0%-40%) between patients and was poorly related to the size of cysts on arthrograms and to the clinical response to therapy. In these studies, the ability to analyse SPECT slices provided a distinct advantage over planar imaging for discriminating between 90Y uptake in cysts and adjacent sites. Retention of 90Y in the total knee was also widely variable, with losses of 2%-38% observed 2 days after injection which, in general, were not fully accounted for by uptake in liver or lymph nodes. The changing distribution of 90Y colloid in the knee during the first two days, as observed in some patients, might explain part of the discrepancy.     

Yttrium-90 and indium-111 labelling, receptor binding and biodistribution of [DOTA0,d-Phe1,Tyr3]octreotide, a promising somatostatin analogue for radionuclide therapy

In vitro octreotide receptor binding of [¹¹¹In-DOTA⁰,d-Phe¹,Tyr³]octreotide (¹¹¹In-DOTATOC) and the in vivo metabolism of⁹⁰Y or¹¹¹In-labelled DOTATOC were investigated in rats in comparison with [¹¹¹In-DTPA⁰]octreotide [¹¹¹In-DTPAOC).¹¹¹In-DOTATOC was found to have an affinity similar to octreotide itself for the octreotide receptor in rat cerebral cortex microsomes. Twenty-four hours after injection of⁹⁰Y or¹¹¹In-labelled DOTATOC, uptake of radioactivity in the octreotide receptor-expressing tissues pancreas, pituitary, adrenals and tumour was a factor of 2–6 that after injection of¹¹¹In-DTPAOC. Uptake of labelled DOTATOC in pituitary, pancreas, adrenals and tumour was almost completely blocked by pretreatment with 0.5 mg unlabelled octreotide, indicating specific binding to the octreotide receptors. These findings strongly indicate that⁹⁰Y-DOTATOC is a promising radiopharmaceutical for radiotherapy and that¹¹¹In-DOTATOC is of potential value for diagnosis of patients with octreotide receptor-positive lesions, such as most neuroendocrine tumours.     

[111In]DOTATOC as a dosimetric substitute for kidney dosimetry during [90Y]DOTATOC therapy: results and evaluation of a combined gamma camera/probe approach

Purpose During [⁹⁰Y]DOTATOC therapy, for determination of kidney doses a conventional approach using co-injected [¹¹¹In]DOTATOC was evaluated for validity, reliability and reproducibility as well as for the influence of methodological variations and bremsstrahlung. Biologically effective doses were estimated by calculating the relative effectiveness (RE) of kidney doses.Methods Fractionated [⁹⁰Y]DOTATOC therapy (n=20 patients, 3.1±0.7 GBq/therapy cycle, 45 therapy cycles) included co-injection of 157±37 MBq [¹¹¹In]DOTATOC and a nephroprotective infusion regimen. From serial gamma camera/probe measurements, individual region of interest (ROI) sets were established and kidney doses were determined according to MIRDOSE3 (corrected for individual kidney mass) by use of three methodological variants: (1) correction for interfering organs (liver/spleen) and background activity, (2) correction for interfering organs alone and (3) no corrections. A phantom study was performed with ¹¹¹ In alone and with ¹¹¹In +⁹⁰Y to estimate the influence of ⁹⁰Y bremsstrahlung.Results Mean kidney dose (method 1, n=20 patients, 20 therapy cycles) was 1.51±0.60 Gy/GBq [⁹⁰Y]DOTATOC (1.41±0.48 Gy/GBq for n=20 patients, 45 therapy cycles). With partial correction (method 2) or no correction (method 3) for interfering activity, kidney doses increased significantly, to 2.71±1.26 Gy/GBq and 3.15±1.22 Gy/GBq, respectively. The span of REs ranged from 1.02 to 1.24. Inter-observer variability was as high as ±32% (±2SD). ⁹⁰Y bremsstrahlung accounted for a 4–11% underestimation of obtained target activity.Conclusion The obtained kidney doses are highly influenced by methodological variations. Full correction for interfering activity clearly underestimates kidney doses. By comparison, ⁹⁰Y bremsstrahlung and variability in the relative effectiveness of kidney doses cause minor bias. Inter-observer variability must be considered when interpreting kidney doses.     

Radiopharmaceuticals for radiation synovectomy: evaluation of two yttrium-90 particulate agents

Radiation synovectomy, a noninvasive therapeutic alternative to surgical synovectomy, has not gained widespread acceptance in the United States because of the lack of a suitable radiopharmaceutical. Two new radioactive particles, [90Y]Ca oxalate and [90Y]ferric hydroxide macroaggregates (FHMA), were developed in our laboratory and evaluated for size, stability, and joint leakage. More than 90% of the [90Y]Ca oxalate particles were in the optimal size range of 1-10 microns, and the unbound activity in serum and synovial fluid was 3.7% to 5.0%. Following injection in rabbit knees, leakage of [90Y]Ca oxalate was 5 +/- 2%, with localization primarily in the bone and virtually no uptake by the lymph nodes or liver. Yttrium-90 FHMA particles were larger (95% greater than 10 microns), and at least on a microscopic level, appeared to distribute homogeneously over the articular surface. Leakage of [90Y]FHMA was initially less but eventually slightly exceeded that of [90Y]Ca oxalate. Nevertheless, both radiopharmaceuticals can provide a satisfactory therapeutic dose to the knee with less than half the leakage and a marked reduction in absorbed dose to nontarget tissues compared to previously tested agents. Ease of preparation, physical characteristics of the 90Y beta ray, and apparent lack of substantial leakage from the joint make these agents extremely attractive for clinical evaluation in rheumatoid arthritis patients who are unresponsive to medical therapy.     

Identification of sentinel lymph node in breast cancer by lymphoscintigraphy and surgical gamma probe with peritumoral injection of scintimammographic agent "99mTc MIbI"

The purpose of this study was to evaluate the efficacy of lymphoscintigraphy and the surgical gamma probe (SGP) with peritumoral injection of 99mTc MIBI in sentinel lymph node (SLN) detection in breast cancer regardless of whether metastatic or not. METHOD: Thirty patients with T1/ T2 breast cancer had peritumoral injections of 99mTc MIBI (74 MBq/0.2 ml at 4 different locations) at 2, 6 and 24 hours before surgery. Anterior, anterolateral, and lateral spot images were taken at 10, 30, 45, 60 and 120 minutes. Counts were collected from the injection site, affected breast tissue, internal mammaries, axillary and supraclavicular regions, and the contralateral side. Peritumoral blue dye was also injected at surgery. The first lymph nodes with counts twice the background tissue and/or with blue dye uptake were surgically isolated, and histopathological evaluations were made. Modified radical mastectomy was performed on all patients. RESULTS: 23/30 patients had lymph nodes in scintigrams and the sentinel lymph nodes were identified with SGP in 25/30 patients. CONCLUSION: Lymphoscintigraphy and subsequent SGP detection with peritumoral injection of 99mTc MIBI can be used for identifying SLN in breast cancer.     

Biologic dosimetry of bone marrow: induction of micronuclei in reticulocytes after exposure to 32P and 90Y.

Bone marrow is the dose-limiting organ in targeted radionuclide therapy. Hence, determination of the absorbed dose to bone marrow from incorporated radionuclides is a critical element in treatment planning. This study investigated the potential of the micronucleus assay in peripheral blood reticulocytes (MnRETs) as an in vivo biologic dosimeter for bone marrow. METHODS: After intravenous administration of 32P-orthophosphate or 90Y-citrate in Swiss Webster mice, DNA damage induced in bone marrow erythroblastoid cells was measured by subsequent scoring of MnRETs in peripheral blood. The response to exponentially decreasing dose rates was calibrated by irradiating animals with external 137Cs-gamma-rays. The gamma-ray dose rate was decreased exponentially, with the dose-rate decrease half-time corresponding to the effective clearance half-time (Te) of the radioactivity from the femoral bone (Te = 64 h for 90Y-citrate and Te = 255 h for 32P-orthophosphate). RESULTS: The maximum MnRETs frequency occurred on the second and third day after injection of 90Y-citrate and 32P-orthophosphate, respectively. The same pattern was observed for exponentially decreasing dose rates of 137Cs-gamma-rays. For each type of exposure, the maximum MnRETs frequency increased in a dose-dependent manner. Using the calibrated dosimeter, the initial dose rates to the marrow per unit of injected activity were 0.0020 cGy/h/kBq and 0.0026 cGy/h/kBq for 32P-orthophosphate and 90Y-citrate, respectively. CONCLUSION: Micronuclei in peripheral blood reticulocytes can be used as a noninvasive biologic dosimeter for measuring absorbed dose rate and absorbed dose to bone marrow from incorporated radionuclides.