Diagnostic and prognostic value of 99mTc-MAA SPECT/CT for treatment planning of 90Y-resin microsphere radioembolization for hepatocellular carcinoma: comparison with planar image.

99mTc-macroaggregated albumin (MAA) imaging is performed before transarterial radioembolization (TARE), in which SPECT/CT is presumed more precise than planar image. However, additive role of SPECT/CT has not been well established. Thirty-four consecutive hepatocellular carcinoma patients of intermediate and advanced stages who underwent 90Y-microsphere TARE were recruited. On pre-treatment planning scan using 99mTc-MAA, image characteristics and absorbed dose for target tumors calculated by partition model methods were estimated on planar image and SPECT/CT, respectively. The measurements were repeated on post-treatment 90Y PET/CT, as the reference standard. Treatment response was assessed and predictive values of image parameters were analyzed. The image characteristics including heterogeneity, necrosis and thrombosis uptake were better delineated on SPECT/CT than planar scan. The agreement and correlation of TNr between SPECT/CT and PET/CT were stronger than those between planar scan and PET/CT. Tumor dose estimated on 99mTc-MAA SPECT/CT was more effective than planar image for prediction of treatment response, with cutoff value 125 Gy (sensitivity of 86% and specificity of 75%). In conclusion, 99mTc-MAA SPECT/CT is more closely correlated with post-treatment 90Y PET/CT, and is more effective for predicting treatment response than planar scan. SPECT/CT is superior to planar image in simulation before 90Y TARE.

The utility of the macro-aggregated albumin lung perfusion scan in the diagnosis and prognosis of hepatopulmonary syndrome in cirrhotic patients candidates for liver transplantation

Background: The macro-aggregated albumin lung perfusion scan (99mTc-MAA) is a diagnostic method for hepatopulmonary syndrome (HPS). Aim: To determine the sensitivity of 99mTc-MAA in diagnosing HPS, to establish the utility of 99mTc-MAA in determining the influence of HPS on hypoxemia in patients with concomitant pulmonary disease and to determine the correlation between 99mTc-MAA values and other respiratory parameters. Methods: Data from 115 cirrhotic patients who were eligible for liver transplantation (LT) were prospectively analyzed. A transthoracic contrast echocardiography and 99mTc-MAA were performed in 85 patients, and 74 patients were diagnosed with HPS. Results: The overall sensitivity of 99mTc-MAA for the diagnosis of HPS was 18.9% (14/74) in all of the HPS cases and 66.7% (4/6) in the severe to very severe cases. In HPS patients who did not have lung disease, the degree of brain uptake of 99mTc-MAA was correlated with the alveolar-arterial oxygen gradient (A-a PO2) (r = 0.32, p < 0.05) and estimated oxygen shunt (r = 0.41, p < 0.05) and inversely correlated with partial pressure of arterial oxygen (PaO2) while breathing 100% O2 (r = -0.43, p < 0.05). The 99mTc-MAA was positive in 20.6% (7/36) of the patients with HPS and lung disease. The brain uptake of 99mTc-MAA was not associated with mortality and normalized in all cases six months after LT. Conclusions: The 99mTc-MAA is a low sensitivity test for the diagnosis of HPS that can be useful in patients who have concomitant lung disease and in severe to very severe cases of HPS. It was not related to mortality, and brain uptake normalized after LT (AU)

No disponible

Role of SPECT-CT in sentinel lymph node biopsy in patients diagnosed with head and neck melanoma.

OBJECTIVE: Assess the role of SPECT-CT in sentinel lymph node (SLN) biopsy in the accurate anatomical location of the SNL in patients with cutaneous head and neck melanoma. MATERIAL AND METHODS: A retrospective study was conducted from February 2010 to June 2013 on 22 consecutive patients with a diagnosis of cutaneous head and neck melanoma (9 female, 13 male), with a mean age of 55 years old and who met the inclusion criteria for SLN biopsy. Patients underwent preoperative scanning after peri-scar injection of (99m)Tc-labeled-nanocolloid. Planar images of the injection-site, whole-body, and SPECT-CT scanning were acquired. RESULTS: Detection rate of SLN reached up to 91% (20/22 patients) by planar lymphoscintigraphy and 95.4% (21/22 patients) by SPECT-CT. SPECT-CT provided an accurate location of SLN in 14/22 patients, enabling to improve the surgical approach (clinical impact: 63.6%). SLN was positive for metastatic cells in 9.1% patients. CONCLUSION: SPECT-CT provides detailed anatomical SLN location and allows detecting a higher number of SLN than planar lymphoscintigraphy. Routine use of SPECT-CT is recommended in order to optimise the SLN detection and location in patients with head and neck melanoma.

Platypnea-orthodeoxia syndrome: importance of patient position for correct diagnosis at the time of 99mTc-MAA injection / Síndrome platipnea-ortodeoxia: importancia de la posición del paciente en el momento de la inyección de 99mTc-MAA para un correcto diagnóstico

A 65-year-old male presented with unexplained hypoxia that became exacerbated by an upright posture (platypnea-orthodeoxia syndrome) secondary to hepatopulmonary syndrome (HPS). A 99mTc-macroaggregated albumin pulmonary perfusion scan revealed a right to left shunt of 29% in the sitting position, which had not been previously detected when the radiotracer injection was performed with the patient in supine position, nor was it diagnosed using another non-invasive imaging method (transthoracic contrast echocardiography and angio-CT). A transesophageal echocardiography was contraindicated due to the presence of esophageal varices. The administration of the radiopharmaceutical in sitting position for the study of the pulmonary perfusion allowed us to confirm the presence of the shunt and consider the patient a candidate for liver transplantation (AU)

Varón de 65 años de edad que presentó hipoxia sin explicación que se exacerbaba en sedestación (síndrome platipnea-ortodeoxia) secundaria a un síndrome hepatopulmonar (SHP). Una gammagrafía de perfusión pulmonar con macroagregados de albúmina 99mTc- reveló un cortocircuito derecha a izquierda, de 29% en la posición sentada que no se había detectado previamente cuando la inyección del radiotrazador se realizó con el paciente en posición supina, ni fue diagnosticado por otros métodos de imagen no invasivo (ecocardiografía transtorácica de contraste y la angio-TC). Una ecocardiografía transesofágica estaba contraindicada debido a la presencia de varices esofágicas. La administración del radiofármaco en sedestación nos permitió confirmar la presencia del cortocircuito y considerar al paciente candidato para trasplante hepático (AU)

(99m)Tc-human serum albumin nanocolloids: particle sizing and radioactivity distribution.

Several parameters affect the biodistribution of administered nanocolloids (NC) for Sentinel Lymph Node (SLN) detection: particle size distribution, number of Tc atoms per particle and specific activity (SA). Relatively few data are available with frequently conflicting results. (99m)Tc-NC-human serum albumin (HSA) Nanocoll®, Nanoalbumon® and Nanotop® were analysed for particles' dimensional and radioactivity distribution, and a mathematical model was elaborated to estimate the number of particles involved. Commercially available kits were reconstituted at maximal SA of 11 MBq/µg HSA. Particles size distribution was evaluated by Dynamic Light Scattering. These data were related to the radioactivity distribution analysis passing labelled NC through three polycarbonate filters (15-30-50-nm pore size) under vacuum. Highest radioactivity was carried by 30-50 nm particles. The smallest ones, even though most numerous, carried only the 10% of (99m)Tc atoms. Nanocoll and Nanotop are not significantly different, while Nanoalbumon is characterized by largest particles (>30 nm) that carried the most of radioactivity (80%). Smallest particles could saturate the clearing capacity of macrophages; therefore, if the tracer is used for SLN detection, more node tiers could be visualized, reducing accuracy of SLN mapping. Manufacturers could implement technical leaflets with particle size distribution and could improve the labelling protocol to provide clinicians useful information.

Comparison of three radiochemical purity control methods of (99m)Tc-macroaggregated albumin.

(99m)Tc-macroaggregated albumin is widely used to diagnose pulmonary embolism. To control the radiochemical purity of this radiopharmaceutical, three rapid control methods using filter, thin layer chromatography or centrifugation, are described in the academic literature. In this paper, the interactions between impurities and (99m)Tc-macroaggregated albumin were presented. For each control method, the influence of these interactions on the determination of the radiochemical purity of labeled macroaggregated albumin was evaluated. Then, a comparison of radiochemical purity obtained by these three methods was performed in normal condition and with different addition of pertechnetate. Finally, a correlation between these three methods was investigated. The results show a specificity difference between these three control methods. However in practice, this difference has no impact on the evaluation of the radiochemical purity of (99m)Tc-macroaggregated albumin by these three methods. In additions, methods are still correlated with pertechnetate additions in (99m)Tc-macroaggregated albumin suspension. Thus, this study demonstrates that these three control methods are exchangeable in radiopharmacy.

Technetium-99m-labeled autologous serum albumin: a personal-exclusive source of serum component.

Technetium-99m human serum albumin ((99m)Tc-HSA) is an important radiopharmaceutical required in nuclear medicine studies. However, the risk of transfusion-transmitted infection remains a major safety concern. Autopreparation of serum component acquired from patient provides a "personal-exclusive" source for radiolabeling. This paper is to evaluate the practicality of on-site elusion and subsequent radiolabeling efficacy for serum albumin. Results showed that the autologous elute contained more albumin fraction than serum without extraction procedure. Good radiochemical purity and stability were demonstrated after radiolabeling. Biodistribution study showed that labeled albumin accumulated immediately in the lung, liver, and kidney. It was cleared steadily and excreted in the urine. The biologic half-life was defined, and all samples passed the pyrogenicity and sterility tests. In conclusion, autoalbumin could be extracted and radiolabeled properly in a nuclear medicine setting. Moreover, the risk of transfusion-transmitted infection associated with nonautologous, multisource (99m)Tc-HSA agents can be reduced.

Technical solutions to ensure safe yttrium-90 radioembolization in patients with initial extrahepatic deposition of (99m)technetium-albumin macroaggregates.

PURPOSE: To evaluate the incidence of extrahepatic deposition of technetium-99m-labeled albumin macroaggregates ((99m)Tc-MAA) after pretreatment angiography, before yttrium-90 radioembolizaton ((90)Y-RE), and to report on technical solutions that can be used to ensure safe delivery of (90)Y-microspheres in patients with initial extrahepatic deposition. MATERIALS AND METHODS: A retrospective analysis of 26 patients with primary and secondary liver malignancies, who were scheduled for treatment with (90)Y-RE in our institution in 2009, was performed. The angiograms and single-photon emission computed tomography images of all patients were reviewed by an interventional radiologist and a nuclear medicine physician, respectively, to identify and localize extrahepatic deposition of (99m)Tc-MAA when present. Subsequently, the technical solutions were used to successfully perform (90)Y-RE in these patients were evaluated and described. RESULTS: Extrahepatic deposition of (99m)Tc-MAA was observed in 8 of 26 patients (31%). In 7 of 8 patients, a second pretreatment angiography was performed to detect the cause of extrahepatic deposition. The technical solutions to enable safe (90)Y microspheres delivery included more distal placement of the microcatheter in the proper/right hepatic artery in 4 of 7 (57%) patients; (super)selective catheterization of multiple segmental branches in 2 of 7 (29%); and additional coiling of a newly detected branch in the remaining patient (14%). This was confirmed by a second MAA procedure. (90)Y-RE was eventually performed in 25 of 26 (96%) patients. No procedure-related complications (<30 days) were observed. CONCLUSION: Extrahepatic deposition of (99m)Tc-MAA after pretreatment angiography did occur in 8 of 26 (31%) patients. The technical solutions as presented allowed safe (90)Y-RE delivery in 25 of 26 (96%) patients.

Sentinel node biopsy in skin melanoma patients--measurements of absorbed doses of radiation to the hands of medical staff.

BACKGROUND AND OBJECTIVES: The goal of this study was to measure absorbed doses of radiation to the hands of medical staff performing sentinel node biopsy (SNB) in skin melanoma patients. METHODS: The study was conducted from January 2004 to May 2004, during SNBs (lymphoscintigraphy-(99m)Tc on albumin carrier, surgery after 24 hr; blue dye; intraoperative detection of gamma radiation) in 22 skin melanoma patients. During lymphoscintigraphy and surgical procedures, 57 highly sensitive thermoluminescent dosimeters (TLDs) were placed on different parts of the hands of the medical staff. RESULTS: Mean doses of radiation recorded on different parts of the hands of the physician injecting the radiotracer ranged from 2.43 to 84.11 microSv for single procedures, ranged from 3.20 to 5.84 microSv for the hands of surgeon, and ranged from 2.65 to 5.47 microSv for the hands of the remaining members of the medical staff. Absorbed doses of radiation to the hands of helping medical staff present in operating room was only slightly lower than absorbed doses to the hands of operating surgeon and assistant surgeon. CONCLUSION: The maximum recorded dose during this study was 1,900 times smaller than the current 1-year dose limit recommended by the International Commission on Radiological Protection (ICRP).

Radiation doses to staff involved in sentinel node operations for breast cancer.

BACKGROUND: The use of radioactive compounds for sentinel node biopsy is now a generally accepted part of the surgical treatment of breast cancer and melanoma, with the risk of radiation exposure to the operating team. The aim of this investigation was to study the levels of this exposure in relation to the permissible radiation dose limits. METHODS: The radiation exposure to the hands and bodies of the operating surgeons (the 'risk persons') was measured by thermoluminescent dosimeters in 79 operations and to the pathologists handling the specimens in 17 cases. Radioactivity and dose rate measurement from tumours and breast specimens were also performed. RESULTS: During an operation the mean skin dose (+/-SD) to the thermoluminescent dosimeters placed at the hand and the abdominal wall were 0.04 +/- 0.04 mSv (79 operations) and 0.01 +/- 0.02 mSv (67 operations) respectively. For the pathologist, the mean hand dose per operation was below the detection limit (17 operations). Correlation between the measured dose rate and the radioactive content of the tumours was 0.998. CONCLUSIONS: The radiation exposure to the staff involved in sentinel node (SN) biopsy for breast cancer using radioactive labelled tracers will be considerably below the permissible limits, even with high numbers of SN biopsy procedures. Pregnant staff members should participate in <100 SN operations.

[The stability of solid food labeled with different radiopharmaceuticals for studying gastric emptying]. / Estabilidad de alimento sólido marcado con diferentes radiofármacos para vaciamiento gástrico.

OBJECTIVE: Sulfur colloid 99mTc-SC, the radiopharmaceutical of choice for solid gastric emptying studies, is not available in our country. It has led us to assess the solid binding stability of seven alternative radiopharmaceuticals that could present adequate fixation to it a priori. MATERIALS AND METHOD: The stability of labelled solid food with seven colloidal 99mTc-radiopharmaceuticals of different sizes and nature (MAA, tin colloid, rhenium sulphide macrocolloid, albumin microcolloid, sulfur nanocolloid, albumin nanocolloid and rhenium sulfur nanocolloid) has been studied by measuring their dissociated activity after two hours digestion in simulated gastric fluid (kept 120' in agitation, in HCl 0.1 M at 37). The survey also assesses radiopharmaceutical labelling stability after two hours digestion in identical conditions by measuring their radiochemical purity in ITLC. RESULTS: In these conditions, MAA, rhenium sulphide macrocolloid, albumin microcolloid and albumin microcolloid present the best behaviour, with an activity linked to food over 90 % of the previously fixed activity. CONCLUSIONS: According to the results, there is no relationship between the radiopharmaceutical size and nature and the stability of its binding to the solid food. Because rhenium sulphide macrocolloid is no longer manufactured and the other three radiopharmaceuticals which have a binding stability to the solid food over 90 % do not include digestive explorations amongst their indications, nowadays, there is a serious legal limitation to carry out this type of studies in our country.

Usefulness of fast protein liquid chromatography as an alternative to high performance liquid chromatography of 99mTc-labelled human serum albumin preparations.

Accurate analysis of the radiochemical purity of 99mTc-labelled preparations is usually performed using an appropriate high performance liquid chromatography (HPLC) system. For the analysis of 99mTc-HSA, the European Pharmacopoeia (Ph. Eur.) prescribes an HPLC system using silica gel for size-exclusion chromatography as the stationary phase. Analysis of 99mTc-HSA preparations with this method allows one to distinguish radiolabelled polymeric, oligomeric, dimeric monomeric forms of albumin as well as small molecular mass impurities such as pertechnetate (99mTcO4-). Due to the relatively short lifetime of this type of column, two fast protein liquid chromatography (FPLC)-type columns were evaluated for their possible usefulness for quality control of 99mTc-HSA preparations, namely Superdex 200 HR 10/30 and Superdex 75 HR 10/30 (Pharmacia, Sweden). Both columns contain a matrix produced by the covalent bonding of dextran to highly cross-linked porous agarose beads. The fractionation range of the Superdex 75 HR 10/30 column was too low to obtain an adequate separation between albumin and its polymerized forms and this column was therefore considered unsuitable for the analysis of 99mTC-HSA preparations. The Superdex 200 column afforded the same pattern and relative amounts of albumin and its polymerized forms as the silica column although the resolution obtained was somewhat lower. A major difference was the fact that 99mTcO4- could not be eluted from the Superdex column but was eluted from the silica column, whereas other small molecular mass, negatively charged 99mTc complexes such as 99mTc-diethylene triamine pentaacetic acid showed an identical elution pattern on both columns. The presence of pertechnetate in 99mTc-HSA preparations, however, can easily be checked using paper chromatography (PC) and acetone as the eluent. Since the lifetime of the Superdex column is twice that of the silica column, FPLC in combination with PC can be recommended as a money-saving and efficient analytical technique for the quality control of 99mTc-HSA preparations.

High performance liquid chromatography of 99mTc labeled human serum albumin using an N-methylpyridinium polymer column.

Human serum albumin (HSA) labeled with 99mTc (99mTc-HSA) was analyzed by high performance liquid chromatography using a 4-vinylpyridinium polymer column which specifically resolved albumin components such as human mercaptalbumin (HMA), human non-mercaptalbumins (HNA), etc. The 99mTc-HSA radiochromatogram revealed that 99mTc-HSA consisted of several components. The radiochromatographic profile was similar to that of 99mTc-HMA prepared with 99mTc and separated HMA. This suggested that HMA participated mainly in 99mTc-labeling of HSA. When HSA was labeled with a stoichiometric concentration of 99Tc, the HMA peak was significantly decreased and new peaks were revealed by absorbance at 280 nm. From these results, the role of HMA in labeling HSA with 99mTc was elucidated.

Wipe tests to assess 99Tcm surface contamination: effects of surface type, swab type and chemical form.

The efficacy of wipe tests for assessing 99Tcm surface contamination was measured. Four types of surface were contaminated with four radiopharmaceuticals and wiped using four types of swab. The fraction of activity removed was measured by direct monitoring for each combination of surface, pharmaceutical and swab. The results obtained showed that wipe tests are neither accurate nor precise. Observed wipe efficacies differed greatly from the customary assumption that 10% of the activity is removed by wiping. Detergent soaked swabs gave a mean efficacy of 40%, although with considerable variation (coefficient of variation 49%). Using these swabs alone the surface type affected efficacy by almost a factor three (floor tile mean efficacy 20%, plastic laminate mean efficacy 57%). In principle this effect might be compensated for by using correction factors according to the surface being swabbed. However, the pharmaceutical type will generally be unknown, and this also affected efficacy by almost a factor of two (eluate mean efficacy 29%, macroaggregated albumin 53%). Overall the results suggest that wipe tests can be used to detect contamination but are unreliable for quantification.