99mTc-MAA Scintigraphy Research Articles

Prior ablation and progression of disease correlate with higher tumor-to-normal liver 99mTc-MAA uptake ratio in hepatocellular carcinoma.

Factors affecting tumor-to-normal tissue ratio (T:N) have implications for patient selection, dosimetry, and outcomes when considering radioembolization for HCC. This study sought to evaluate patient, disease specific, and technical parameters that predict T:N as measured on planning pre-90Y radioembolization 99mTc-MAA scintigraphy for hepatocellular carcinoma (HCC). 99mTc-MAA hepatic angiography procedures with SPECT/CT over a 4-year period were reviewed. Data recorded included patient demographics, details of underlying liver disease, tumor size, history of prior treatments for HCC and technical parameters from angiography. Anatomic-based segmentation was performed in 93 cases for measurement of tumor and perfused liver volumes and SPECT counts. T:N were calculated and correlated with collected variables. Mean calculated T:N was 2.52. History of prior ablation was significantly correlated with higher T:N (mean 3.39 vs 2.24, p = 0.003). Cases in which mapping was being performed for treatment of disease progression was significantly correlated with higher T:N (mean 3.35 vs 2.14, p = 0.001). Larger tumor size trended toward lower T:N (p = 0.052). Patients with history of ablation and those undergoing treatment for disease progression have higher T:N and, therefore, could be considered for radioembolization preferentially over alternative treatments.

Development of a scatter correction technique for planar 99mTc-MAA imaging to improve accuracy in lung shunt fraction estimation

PurposePrior to 90Y selective internal radiation therapy (SIRT) treatment, 99mTc-MAA scintigraphy imaging is used in the estimation of the lung shunt fraction (LSF). Planar imaging is recommended for determining a LSF ratio. However, the estimate may be affected by scatter contributions, attenuation and respiratory motion. The objective of this study was to correct for the effects of scatter in the LSF, towards the determination of a more accurate estimation method of LSF derived from planar scintigraphy imaging, which is recommended by international guidelines. MethodsThe open access SIMIND Monte Carlo modelling software was used to estimate an optimum scatter window (SW) for scatter correction. The uncertainties associated with scatter and scatter contributions from the liver on the LSF were evaluated using an anthropomorphic thorax phantom and a virtual Vox-Man phantom. A brief retrospective examination of patient scans and tumour location investigated the impact that the inclusion of the simulated scatter corrections had on the LSF estimation. ResultsThe percentage overestimation of the manufacturer recommended method of LSF estimation was 192%. SW corrections improved the uncertainty to within 19% for the range of known LSFs. Similar findings were observed for our patient and tumour location studies. ConclusionThe incorporated scatter corrections can significantly improve the accuracy of the LSF estimation, thereby providing a robust gamma camera, patient and tumour depth specific correction which is easily implementable. This is supported by Monte Carlo, phantom and preliminary patient studies.

Same-day 90Y radioembolization: implementing a new treatment paradigm.

To assess the feasibility of conducting pretreatment mesenteric angiography, coil embolization, 99mTc macroaggregated albumin (99mTc-MAA) scintigraphy, and 90Y radioembolization treatment in a single, same-day, combined outpatient encounter. This was a retrospective study of 78 patients treated during the period 2008-2015 who were managed in a single outpatient encounter under the guidance of the Interventional Radiology Department and The Nuclear Medicine Department. Pretreatment planning was performed by reviewing baseline imaging and estimated perfused liver volume bearing the tumor. The region of interest was estimated using 3-D software; this value was used for dosimetry planning. Maximum lung shunting fractions of 10% for hepatocellular carcinoma and 5% for liver metastases were assumed. Subsequently, hepatic angiography and 99mTc-MAA scintigraphy were performed followed by 90Y treatment in one outpatient encounter. Total in-room procedure time was recorded. All patients underwent same-day angiography, 99mTc-MAA scintigraphy and 90Y radioembolization. Of the 78 patients, 16 received multiple segmental treatments to both lobes, 44 received treatment to the right lobe, and 18 received treatment to the left lobe. The median dose was 106Gy. The median number of 90Y vials needed was two (range one to six). The median in-room time was 160min (75-250min). The residential status of the patients was as follows, 18% (14/78) were local residents, 55% (43/78) traveled from outside the city limits, 18% (14/78) were from out-of-state, and 9% (7/78) were resident abroad. Of the 78 patients, 61 (77%) had hepatocellular carcinoma, and 17 (22%) had liver metastases. The median lung dose was 3.5Gy. This study demonstrated the feasibility of same-day 90Y evaluation and treatment while maintaining the principles of safe and effective 90Y infusion including tumoricidal dosimetry (lobar, segmentectomy), minimization of nontarget flow, and minimization of lung dose. This paradigm translates into expeditious cancer care and significant cost savings.

Intrapulmonary vascular dilatation evaluated by 99mTc-MAA scintigraphy and its association with portal hypertension in schistosomiasis.

BackgroundPortal hypertension is responsible for various complications in patients with schistosomiasis, among them intrapulmonary vascular dilations (IPVD). In cirrhotic patients the presence of IPVD is a sign of poor prognosis, but in patients with hepatosplenic schistosomiasis (HSS) there are no studies assessing the significance of this change. The aim of this study was to evaluate the occurrence of IPVD through 99mTc-MAA scintigraphy in patients with HSS and its relationship with clinical, laboratory, endoscopic and ultrasound parameters.MethodsCross-sectional study evaluating 51 patients with HSS. Patients were diagnosed with IPVD when the brain uptake of 99mTc-MAA was higher than 6%. Subsequently, they were divided according to presence (G1) or absence (G2) of IPVD and variables were compared between groups.ResultsOverall, 51 patients with mean age of 56±12 years were assessed. IPVD was observed in 31 patients (60%). There was no statistically significant differences between groups when clinical, laboratory and endoscopic parameters were compared. Regarding ultrasound parameters, the splenic vein diameter was smaller in G1 (0.9±0.3 cm) compared to G2 (1.2±0.4 cm), p = 0.029.ConclusionIn patients with HSS, the occurrence of IPVD by 99mTc-MAA scintigraphy was high and was associated with lower splenic vein diameter, which can be a mechanism of vascular protection against portal hypertension. However, more studies are needed to determine the clinical significance of the early diagnosis and natural evolution of IPVD in this population.

Evaluation of the Response to Selective Internal Radiation Therapy in Patients With Hepatocellular Cancer According to Pretreatment 99mTc-MAA Uptake

The aim of the study was to evaluate if there is a prognostic importance of pretreatment Tc-MAA uptake of liver lesion of patients who received Y selective internal radiation therapy (SIRT) treatment for hepatocellular cancer (HCC) or not. Nineteen patients (5 female and 14 male patients; mean age, 64.5 ± 14.7 years; range, 57-73 years) who received SIRT treatment in our department for HCC between June 2008 and May 2011 were included in the study. All the patients have undergone Tc-MAA scintigraphy within 2 weeks' period before treatment for evaluation of presence of extrahepatic uptake. Patients were evaluated according to their lesions' Tc-MAA uptake patterns. Response to the treatment, presence of progression after treatment, and progression-free survival of all the patients were calculated. Treatment has been administered on the right and left lobes of the liver in 18 and 1 patient, respectively. The mean treatment dose was estimated as 1.4 + 1.0 GBq. In the pretreatment Tc-MAA scintigraphy, liver lesions of 5 patients were hypoactive, and 14 patients were hyperactive. In the hypoactive group, whereas 2 patients (40%) were responders to treatment, 3 were nonresponders (60%). In the hyperactive group, 8 (58%) and 6 (42%) patients were responders and nonresponders, respectively (P = 0.51). Disease progression was seen in 4 (80%) and 8 patients (58%) in the hypoactive group and hyperactive groups, respectively (P = 0.36). Progression-free survival of the hypoactive group was calculated as 8 ± 4.3 months and of the hyperactive group 11 ± 4.7 months (P = 0.22). Despite the small number of patients, this study revealed that there is no significance between tumor response and progression rates of patients who received SIRT for HCC with or without pretreatment Tc-MAA uptake in liver lesions. Selective internal radiation therapy could be safely performed in patients who have hypoactive lesions in Tc-MAA scintigraphy.

Computed tomography hepatic arteriography has a hepatic falciform artery detection rate that is much higher than that of digital subtraction angiography and 99mTc-MAA SPECT/CT: Implications for planning 90Y radioembolization?

PurposeTo compare the hepatic falciform artery (HFA) detection rates of digital subtraction angiography (DSA), computed tomography hepatic arteriography (CTHA) and 99mTc-macroaggregated albumin (99mTc-MAA) single photon emission computed tomography with integrated CT (SPECT/CT) and to correlate HFA patency with complication rates of yttrium-90 (90Y) radioembolization. Material and methodsFrom August 2008 to November 2010, 79 patients (range 23–83 years, mean 62.3 years; 67 male) underwent pre-treatment DSA, CTHA and 99mTc-MAA scintigraphy (planar/SPECT/CT) to assess suitability for radioembolization with 90Y resin microspheres. Thirty-seven patients were excluded from the study, because CTHA was performed with a catheter position that did not result in opacification of the liver parenchyma adjacent to the falciform ligament. DSA, CTHA and 99mTc-MAA SPECT/CT images and medical records were retrospectively reviewed. ResultsA patent HFA was detected in 22 of 42 patients (52.3%). The HFA detection rates of DSA, CTHA and 99mTc-MAA SPECT/CT were 11.9%, 52.3% and 13.3%, respectively (p<0.0001). An origin from the segment 4 artery was seen in 51.7% of HFAs. Prophylactic HFA coil-embolization prior to 90Y microspheres infusion was performed in 2 patients. Of the patients who underwent radioembolization with a patent HFA, none developed supra-umbilical radiation dermatitis. One patient experienced epigastric pain attributed to post-embolization syndrome and was managed conservatively. ConclusionThe HFA detection rate of CTHA is superior to that of DSA and 99mTc-MAA SPECT/CT. Complications related to non-target radiation of the HFA vascular territory rarely occur, even in patients undergoing radioembolization with a patent HFA.

Consolidation of Hepatic Arterial Inflow by Embolization of Variant Hepatic Arteries in Preparation for Yttrium-90 Radioembolization

Purpose Before yttrium-90 ( 90Y) radioembolization administration, the authors consolidated arterial inflow by embolizing variant hepatic arteries (HAs) to make microsphere delivery simpler and safer. The present study reviews the technical and clinical success of these consolidation procedures. Materials and Methods Preparatory and treatment angiograms were retrospectively analyzed for 201 patients. Variant HAs were coil-embolized during preparatory angiography to simplify arterial anatomy. Collateral arterial perfusion of territories previously supplied by variant HAs was evaluated by digital subtraction angiography (DSA), C-arm computed tomography (CT), and technetium-99m ( 99mTc)–macroaggregated albumin (MAA) scintigraphy, and by follow-up evaluation of regional tumor response. Results A total of 47 variant HAs were embolized in 43 patients. After embolization of variant HAs, cross-perfusion into the embolized territory was depicted by DSA and by C-arm CT in 100% of patients and by 99mTc-MAA scintigraphy in 92.7%. Uniform progressive disease prevented evaluation in 33% of patients, but regional tumor response in patients who responded supported successful delivery of microspheres to the embolized territories in 95.5% of evaluable patients. Conclusions Embolization of variant HAs for consolidation of hepatic supply in preparation for 90Y radioembolization promotes treatment of affected territories via intrahepatic collateral channels.

Abstract No. 31: Impact of using c-arm CT on treatment planning for yttrium-90 radioembolization

To prepare for yttrium-90 (90Y) radioembolization therapy, digital subtraction angiography (DSA) and technetium- 99m-labeled macroaggregated albumin (99mTc MAA) scintigraphy are used for treatment planning and detection of potential nontarget embolization. We investigated how c-arm computed tomography (CACT) affects treatment planning as an adjunct to these conventional imaging modalities. From March 2007 to October 2008, 50 consecutive patients (26 men, 24 women; mean age, 58 years; range, 21-75 y) undergoing radioembolization were evaluated by CACT in addition to DSA and 99mTc MAA scintigraphy during treatment planning, and their records were retrospectively reviewed. CACT was performed by selective injection of diluted contrast at the planned site of microsphere administration, and post-processing with soft-tissue multiplanar reconstructions. CACT images were analyzed real-time to determine completeness of perfusion of the targeted hepatic territory and to survey neighboring viscera for extrahepatic perfusion. Additional angiography, embolization, and/or catheter repositioning was performed accordingly. In 23 of 50 cases (46%), extrahepatic enhancement or incomplete tumor perfusion seen on CACT affected the treatment plan. In 14 patients (28%), the findings were evident exclusively on CACT and not detected by DSA. When comparing CACT versus 99mTc MAA scintigraphy, CACT showed eight cases of extrahepatic enhancement (16%) that were not evident on 99mTc MAA imaging. CACT findings directed the additional embolization of vessels or repositioning of the microcatheter for better contrast agent and presumed microsphere distribution. A case of gastric ulcer from nontarget embolization caused by reader error was observed. Due to its high three-dimensional spatial and contrast resolution, contrast-enhanced CACT provides additional information about tumor and tissue perfusion not currently detectable by standard DSA or 99mTc MAA imaging. As the availability of flat-panel systems becomes more widespread, optimization of microsphere delivery by incorporating CACT techniques may become standard of practice.

Treatment of hepatocellular carcinoma by means of radiopharmaceuticals

Several techniques have been developed for radionuclide therapy of hepatocellular carcinoma (HCC). Medical literature databases (Pubmed, Medline) were screened for available literature and articles were critically analysed as to their scientific relevance. In a palliative setting, intra-arterial administration of 131I-Lipiodol yields responses in 17-92% of patients. According to a randomised study, 131I-Lipiodol was far better tolerated than classic chemo-embolisation. The additive value of a single 131I-Lipiodol administration following partial liver resection for HCC was evaluated and evidence is available that adjuvant radionuclide treatment reduces the recurrence rate. Data concerning the role of 131I-Lipiodol in bridging patient to liver transplantation are scarce but suggest a potential benefit in terms of reducing the drop-out rate while patients are listed for transplantation. 188Re- and 90Y-labelled conjugates are emerging and initial clinical data are promising. Treatment of HCC with 90Y-labelled microspheres is likely as efficacious as treatment with radiolabelled Lipiodol but pretreatment 99mTc-MAA scintigraphy is required in order to exclude patients with significant lung shunting. Several antibodies targeting antigens expressed on HCC have been radiolabelled, almost exclusively with 131I, and evaluated in a preclinical or clinical setting. The use of radiolabelled Lipiodol and microspheres allows for selective targeting of HCC with limited toxicity. Prospective, randomised controlled trials demonstrating that both treatment modalities may provide a survival benefit in a palliative setting are mandatory. In addition, future research should focus on the complementary role of radionuclide treatment in patients at risk for recurrent disease following partial liver resection or while awaiting liver transplantation.

Distribuição do fluxo sangüíneo pulmonar na bronquiolite viral aguda

To assess lung perfusion patterns in inpatients with acute viral bronchiolitis using quantitative 99mTc-MAA scintigraphy so as to establish an association with clinical and radiological findings. A comparative, prospective case series study with a focus on diagnosis was carried out in a population of patients with acute viral bronchiolitis admitted to Hospital de Clínicas de Porto Alegre. Inclusion criteria were age between 1 and 24 months and first sudden-onset wheezing episode, suggesting bronchiolitis. The patients in the study were submitted to clinical, radiological and 99mTc-MAA lung perfusion evaluation during the first 24 hours of admission. Statistical analysis employed t test, taking into consideration a significance level of 0.05. The regional distribution of lung blood flow in the 38 patients studied was more pronounced in the upper section of the left lung in relation to the right lung (P<0.001). The distribution gradients of blood flow between the upper and middle and upper and lower sections were higher in the left lung (P<0.001). The distribution gradients of blood flow between the middle and lower sections were higher in the right lung, but without significance. The distribution gradient of the pulmonary flow in the anteroposterior axis was >1.0 in the upper and middle sections of both lungs. In the lower section it was >1.0 only in the right lung (P<0.007). There was no association between lung blood flow distribution patterns and clinical or radiological findings. There was no evidence of an association between lung blood flow distribution and ventilation-perfusion ratio in hospitalized infants with acute viral bronchiolitis; only a tendency to redirect lung blood flow towards upper lung sections was observed.

Inspired anaesthetic gas humidification improves thermal uniformity during canine whole body hyperthermia.

Supplying warmed saturated water vapour in anaesthetic gases during whole body hyperthermia (WBH) could potentially improve thermal uniformity in the trachea and esophagus. Four normal dogs were anaesthetized for WBH at 42 degrees C. A Puritan Bennett Cascade humidifier was used to supply anaesthetic gases saturated with water vapour at an average airway temperature of either 42 degrees C or 38 degrees C. Esophageal temperature was monitored at the thoracic inlet and 5 cm cephalad. Thermal dose was estimated by calculating equivalent minutes for an isoeffect at 43 degrees C (CEM 43 degrees Tx, where Tx is the site of temperature measurement). Endotracheal mucociliary transport velocity (MCTV) was determined before and 48 h following WBH by 99mTc-MAA scintigraphy. Compared to the 38 degrees C humidified gas group, dogs receiving 42 degrees C humidified gas reached 42 degrees C faster (p = 0.02) and had CEM 43 degrees T(esophageal) values equivalent to the target CEM 43 degrees T(rectal). Endotracheal MCTV with 42 degrees C humidified gas, however, was reduced 53% from baseline 48 h following WBH (p = 0.02). With 38 degrees C humidified gas, endotracheal mucociliary transport velocity was unchanged from baseline 48 h post WBH. Tracheal histology was examined using light and electron microscopy in four additional dogs euthanatized following 90 min of 42 degrees C humidified gas combined with WBH. There was no histological evidence of tracheal or lung thermal damage with 42 degrees C humidified gas in these four dogs. However, a moderate increase in tracheal goblet cell secretory granule staining was observed. This change could imply temporary heat-induced ciliary microtubule dysfunction, rather than decreased mucus production, as the likely mechanism of reduced mucociliary transport velocity 48 h following WBH. Administration of 42 degrees C humidified anaesthetic gases with WBH improves heating rate and esophageal thermal uniformity but temporarily depresses tracheal mucociliary transport velocity.

Assessment of perfusion patterns during hepatic artery infusion chemotherapy: EOE-13 CT and 99mTc-MAA scintigraphy.

Hepatic perfusion patterns were evaluated in five patients receiving hepatic artery infusion chemotherapy. All patients underwent 99mTc macroaggregated albumin (99mTc-MAA) scintigraphy and CT with EOE-13. In each case, the diagnostic agent was administered through the infusion catheter at 0.66 ml/min. Hepatic perfusion patterns were identified with both imaging methods, but CT with EOE-13 yielded more precise anatomic detail and was unique in demonstrating the perfusion status of each hepatic metastasis. Further evaluation of EOE-13 for this purpose is warranted.

Transmission Computed Tomographic Diagnosis of Experimentally Produced Acute Pulmonary Vascular Occlusion in the Dog

Acute experimental pulmonary arterial occlusions were produced in 5 dogs. The chest was subsequently imaged with computed tomography (CT), 99mTc-MAA scintigraphy, and plain radiography. Gamma images revealed all 6 lesions, and plain radiographs were uniformly negative. Enhanced CT scans demonstrated 3 of 5 lesions, and unenhanced scans revealed 1 of 6. CT findings were variable.