Evaluación mediante PET/TAC con 18FDG de la actividad metabólica hepática en pacientes con hígado graso de origen no alcohólico / Evaluation of hepatic metabolic activity in non-alcoholic fatty livers on 18FDG PET/CT

Objetivo. El hígado se ha usado como órgano de referencia para evaluar la captación anormal de la 18F-fluoro-2-deoxi- d -glucosa (18FDG). Algunos trabajos publicados muestran que la esteatosis hepática modifica la captación hepática de 18FDG, mientras que otros no encuentran modificaciones. Este trabajo ha estudiado si la captación hepática de 18FDG se ve afectada por la infiltración grasa difusa del hígado. Material y métodos. En este estudio se incluyeron 156 casos. Se definieron diferentes grupos de pacientes de acuerdo a las unidades Hounsfield (HU) del hígado. En todos los pacientes, las HU se calcularon a partir de la TAC sin contraste. Además se calculó el SUVmedio y el SUVmáx en el estudio PET con 18FDG. Para ello se dibujaron regiones de interés (ROI) sobre el área hepática. Se realizó una comparación estadística del SUVmedio y SUVmáx medidos en los pacientes con hígado graso y en un grupo control. Resultados. En el grupo de pacientes, los promedios de SUVmedio y SUVmáx fueron 2,58±0,66 y 3,94±1, respectivamente; en el grupo control fueron 2,54±0,57 y 3,7±0,88, respectivamente. Encontramos que los promedios del SUVmedio y SUVmáx en los pacientes con hígado graso no fueron significativamente diferentes a los valores del grupo control (p>0,05). Asimismo, no detectamos correlación estadísticamente significativa entre los valores de la densidad media del hígado, medida en HU, y el promedio de los SUV (p>0,05). Conclusión. La infiltración grasa no parece tener un efecto significativo sobre la captación hepática de 18FDG. Por ello, el hígado se puede usar como órgano de referencia en los estudios PET con 18FDG realizados en pacientes con enfermedad grasa hepática(AU)

Objective. The liver has been used as a reference organ for the assessment of abnormal 18F-fluoro-2-deoxy- d -glucose (18FDG) in the body. Some researchers found that hepatosteatosis significantly changed the hepatic 18FDG uptake, while others did not. This study investigated whether the liver's 18FDG uptake was affected by the diffuse fatty infiltration of the liver. Material and methods. A total of 156 cases were included in this study. Different patient groups were defined according to the liver Hounsfield unit (HU). The HU was calculated from an unenhanced CT, for all patients, and we calculated the mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on an 18FDG PET scan. For this purpose, we placed regions of interest (ROIs) on the liver image. We statistically compared the SUVmean and SUVmax measured in the fatty liver patients and the control group. Results. The average SUVmean and SUVmax values were calculated as 2.58±0.66 and 3.94±1, respectively, in the patient group and 2.54±0.57 and 3.7±0.88, respectively, in the control group. We found the average SUVmean and SUVmax values in the fatty liver group and its subsets were not significantly different from the values in the control group (p>0.05). We also did not find any statistically significant correlation between average liver density (HU) and the average SUV values (p>0.05). Conclusion. Fatty infiltration may not have a significant effect on the liver's 18FDG uptake. Thus, the liver may be used as a reference or comparator on 18FDG PET scans in patients with fatty liver disease(AU)

Evaluation of hepatic metabolic activity in non-alcoholic fatty livers on 18FDG PET/CT.

OBJECTIVE: The liver has been used as a reference organ for the assessment of abnormal (18)F-fluoro-2-deoxy-d-glucose ((18)FDG) in the body. Some researchers found that hepatosteatosis significantly changed the hepatic (18)FDG uptake, while others did not. This study investigated whether the liver's (18)FDG uptake was affected by the diffuse fatty infiltration of the liver. MATERIAL AND METHODS: A total of 156 cases were included in this study. Different patient groups were defined according to the liver Hounsfield unit (HU). The HU was calculated from an unenhanced CT, for all patients, and we calculated the mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on an (18)FDG PET scan. For this purpose, we placed regions of interest (ROIs) on the liver image. We statistically compared the SUVmean and SUVmax measured in the fatty liver patients and the control group. RESULTS: The average SUVmean and SUVmax values were calculated as 2.58±0.66 and 3.94±1, respectively, in the patient group and 2.54±0.57 and 3.7±0.88, respectively, in the control group. We found the average SUVmean and SUVmax values in the fatty liver group and its subsets were not significantly different from the values in the control group (p>0.05). We also did not find any statistically significant correlation between average liver density (HU) and the average SUV values (p>0.05). CONCLUSION: Fatty infiltration may not have a significant effect on the liver's (18)FDG uptake. Thus, the liver may be used as a reference or comparator on (18)FDG PET scans in patients with fatty liver disease.

El papel de FDG-PET/TAC en pacientes con cáncer de ovario con marcadores tumorales altos o lesión con sospecha con TAC con contraste en la evaluación de recurrencia y/o en la determinación de metástasis intraabdominales / The Role of FDG-PET/CT in Ovarian Cancer Patients with High Tumor Markers or Suspicious Lesion on Contrast-Enhanced CT in Evaluation of Recurrence and/or in Determination of Intraabdominal Metastases

Objetivos. Este estudio retrospectivo fue diseñado para investigar el papel de una tomografía por emisión de positrones con 18F-fluorodeoxiglucosa/tomografía axial computerizada (PET-FDG) (FDG- PET/CT) en la determinación de recurrencia y/o metástasis intraabdominal en pacientes con cáncer de ovario con marcadores tumorales aumentados o lesión de sospecha detectada con TAC abdominal con contraste (TAC-c). Materiales y métodos. Se realizó un estudio PET/TAC en 34 pacientes femeninos tratados por cáncer de ovario verificado histopatológicamente para reestratificación y sospecha de recurrencia. Se incluyeron a pacientes con informe patológico, niveles de marcador tumoral, TAC-c y PET/TAC dentro de un mes del estudio. Resultados. Se reclutaron a 34 pacientes, 25 de las cuales tenían un nivel alto del marcador tumoral CA 125. Las 9 pacientes restantes tenían sospecha de recurrencia en la imagen del TAC-c con niveles del marcador tumoral normales. Se confirmaron recurrencia con re-operación y biopsia (n=4), seguimiento clínico y de imagen (n=21) en 25 pacientes y marcadores tumorales elevados. No se encontraron enfermedad recurrente en 5 de 25 pacientes en la imagen TAC-c y 1 de 25 pacientes en la imagen PET/TAC con altos niveles de CA125. Tanto TAC-c y el PET/TAC demostraron enfermedad recurrente en 19 de 25 pacientes. La sensibilidad, especificidad y presión del PET/TAC fueron 96,1, 100 y 97%, respectivamente. Conclusión. PET/TAC es un método beneficioso para la detección de recurrencia en pacientes con un nivel de CA 125 en suero elevado y hallazgos negativos en la TAC, o con un nivel normal de CA 125 y recurrencia detectado por TAC llevado a cabo debido a síntomas clínicos(AU)

Objectives. This retrospective study was designed to investigate the role of fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in determination of recurrence and/or intraabdominal metastasis in patients with ovarian cancer having increased tumor markers or suspicious lesion detected by a contrast-enhanced abdominal CT (ceCT). Materials and methods. A total of 34 female patients who were treated for histopathologically proven ovarian cancer, underwent PET/CT examination for restaging and suspected recurrence. Patients with pathology report, tumor marker levels, ceCT and PET/CT performed within one month were included in the study. Results. A total of 34 patients were included in the study. 25 of 34 patients had high tumor marker (CA 125) level. The remaining 9 patients had suspected recurrence on ceCT imaging with normal tumor marker levels. Recurrence was confirmed by re-operation and biopsy (n=4), clinical and imaging follow-up (n=21) in 25 patients with elevated tumor markers. Recurrent disease was not shown in 5 of 25 patients on ceCT imaging and 1 of 25 patients on PET/CT imaging with high CA125 values. Both ceCT and PET/CT revealed recurrent disease in 19 of 25 patients. PET/CT showed more lesions in 11 of 19 patients. Sensitivity, specificity and accuracy of the PET/CT were 96.1%, 100% and 97%, respectively. Conclusion. PET/CT is found as a beneficial method for detection of the recurrence, in patients with increased serum CA 125 level and negative CT findings or with normal CA 125 level and recurrence detected by CT which was performed due to clinical symptoms(AU)

The role of FDG-PET/CT in ovarian cancer patients with high tumor markers or suspicious lesion on contrast-enhanced CT in evaluation of recurrence and/or in determination of intraabdominal metastases.

OBJECTIVES: This retrospective study was designed to investigate the role of fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in determination of recurrence and/or intraabdominal metastasis in patients with ovarian cancer having increased tumor markers or suspicious lesion detected by a contrast-enhanced abdominal CT (ceCT). MATERIALS AND METHODS: A total of 34 female patients who were treated for histopathologically proven ovarian cancer, underwent PET/CT examination for restaging and suspected recurrence. Patients with pathology report, tumor marker levels, ceCT and PET/CT performed within one month were included in the study. RESULTS: A total of 34 patients were included in the study. 25 of 34 patients had high tumor marker (CA 125) level. The remaining 9 patients had suspected recurrence on ceCT imaging with normal tumor marker levels. Recurrence was confirmed by re-operation and biopsy (n=4), clinical and imaging follow-up (n=21) in 25 patients with elevated tumor markers. Recurrent disease was not shown in 5 of 25 patients on ceCT imaging and 1 of 25 patients on PET/CT imaging with high CA125 values. Both ceCT and PET/CT revealed recurrent disease in 19 of 25 patients. PET/CT showed more lesions in 11 of 19 patients. Sensitivity, specificity and accuracy of the PET/CT were 96.1%, 100% and 97%, respectively. CONCLUSION: PET/CT is found as a beneficial method for detection of the recurrence, in patients with increased serum CA 125 level and negative CT findings or with normal CA 125 level and recurrence detected by CT which was performed due to clinical symptoms.

Post-surgical ablation of thyroid remnants with high-dose (131)I in patients with differentiated thyroid carcinoma.

The aims of this study were to evaluate the efficacy of an empirically determined "fixed" high ablative dose of radioiodine ((131)I) therapy and to determine the utility of ultrasonography (US) in dose determination. A retrospective analysis was performed of 242 thyroid cancer cases treated with "fixed" high-dose (131)I for ablation of thyroid remnants without a pre-ablative (131)I diagnostic scintigraphy or radioiodine uptake study. Treatment doses ranged from 1850 MBq (50 mCi) to 7.4 GBq (200 mCi). The selection of the treatment dose was based on the surgical and pathological findings as well as the remnant thyroid volume calculated by US. A successful ablation was defined as the absence of activity in the thyroid bed on subsequent imaging studies. Successful ablation was obtained in 218 of the 242 patients (90%). In 162 of the 218 patients (74.3%), successful ablation was achieved after a single (131)I treatment. The remnant thyroid volume calculated by US was significantly different (P=0.04) between those who were successfully ablated and those who were not. The total (131)I dose needed for successful ablation was significantly higher in males (P=0.003). Patients with higher post-operative thyroglobulin (Tgb) levels and patients with a higher stage of disease required higher doses (P=0.036 and P=0.021 respectively). Serum Tgb levels were under 10 ng.ml(-1) in 220 of the 242 patients (90%) following radioiodine ablation while not receiving L-thyroxine suppression. Nineteen patients (7.8%) showed metastases on post-therapy scan and successful treatment was achieved in 11 of 19 (57.8%). Four of the 19 patients with distant metastases (revealed on post-treatment scan) were found to have been given a treatment dose of less than 200 mCi based on the proposed empirical approach. These results indicate that "fixed" high-dose (131)I treatment is clinically feasible with an acceptable dose underestimation rate, and the utilization of US in the determination of the thyroid remnant volume provides more accurate and reproducible results.

Comparison of In-111 octreotide and Tc-99m (V) DMSA scintigraphy in the detection of medullary thyroid tumor foci in patients with elevated levels of tumor markers after surgery.

PURPOSE: In this retrospective study, the authors evaluated the utility of In-111 octreotide (OctreoScan) and Tc-99m (V) DMSA scintigraphy for the localization of recurrent metastatic tumor foci in patients with medullary thyroid cancer (MTC) and compared the findings with those of conventional radiologic imaging methods. METHODS: The scintigraphic images were compared with computed tomography (CT) and magnetic resonance imaging (MRI) and ultrasonography (US) in 14 patients (8 men, 6 women; age range, 22 to 74 years) with elevated calcitonin and carcinoembryonic antigen levels after total thyroidectomy. All scintigraphic image findings were evaluated qualitatively as mild uptake (+) and moderate to marked uptake (++). RESULTS: In-111 octreotide may be superior to Tc-99m (V) DMSA for the detection of tumor foci of patients with MTC on a patient basis (78.5% versus 57.1%) and on a lesion basis (44.1% versus 30.2%). The sensitivity rate for In-111 octreotide (78.5%) was also similar to that of CT and MRI on a patient basis. Conversely, the combined use of Tc-99m (V) DMSA and In-111 octreotide revealed the best sensitivity rate (85.7%) on a patient basis, whereas the combined use of CT and MRI showed the best sensitivity rate (81.3%) on a lesion basis. CONCLUSIONS: These findings suggest that In-111 octreotide is superior to Tc-99m (V) DMSA and has a similar sensitivity rate to CT and MRI for the diagnosis of recurrent or metastatic MTC. Although the combined use of In-111 octreotide and Tc-99m (V) DMSA was most sensitive, the combined use of CT and MRI with radionuclide imaging methods may better detect more metastatic tumor foci.

Comparison of Tc-99m EC and Tc-99m DTPA captopril scintigraphy to diagnose renal artery stenosis.

PURPOSE: Although, captopril scintigraphy is a well established method to detect renovascular hypertension, the optimal radiopharmaceutical for this test remains to be determined. Recently, Tc-99m ethylenedicysteine (Tc-99m EC) appeared as an alternative agent for captopril scintigraphy. The aim of this study was to compare the diagnostic accuracy of Tc-99m EC with Tc-99m DTPA, which is a well-established renal radiopharmaceutical for the captopril test. METHODS: Nineteen hypertensive patients who had various degrees of renal artery stenosis on angiography were included in the study. All patients had baseline and captopril Tc-99m EC and Tc-99m DTPA scintigraphy within a 1-week period. The results were compared with angiography and in eight patients with changes in blood pressure after revascularization. The images were interpreted without knowledge of the angiography and revascularization data as low, intermediate, or high probability for hemodynamically significant renal artery stenosis, which was defined as an area of stenosis exceeding 50%. RESULTS: Tc-99m EC and Tc-99m DTPA study results were in agreement in 16 of the 19 patients. In two patients with branch artery stenosis, Tc-99m EC was definitely superior to Tc-99m DTPA and correctly identified the probability of stenosis on scintigraphy. On kidney analysis, Tc-99m EC had a slightly greater diagnostic sensitivity compared with Tc-99m DTPA (79% vs. 68%; P > 0.05 by the chi-squared test) but equal specificity (93% for both agents). Both Tc-99m EC and Tc-99m DTPA showed the same accuracy in predicting the outcome after revascularization in all but one patient with branch artery stenosis, in whom Tc-99m EC accurately predicted a successful outcome of the intervention but Tc-99m DTPA did not. Tc-99m EC had better renal uptake in patients with decreased renal function and provided more dramatic evidence of renogram changes after captopril intervention, which resulted in more confident interpretation. CONCLUSIONS: There is no significant difference between Tc-99m EC and Tc-99m DTPA captopril scintigraphy for detecting renal artery stenosis. However, because of the better imaging characteristics and more confident interpretation provided by the dramatic changes in the degree of renogram abnormality after captopril intervention, Tc-99m EC captopril scintigraphy should be used, particularly in patients with decreased renal function or branch artery stenosis.

Prediction of response to revascularization in patients with renal artery stenosis by Tc-99m-ethylenedicysteine captopril scintigraphy.

The aim of the present study was to assess the predictive value of captopril scintigraphy with the new renal agent 99mTc-ethylenedicysteine (99mTc-EC) for post-interventional improvement in blood pressure. Twelve patients who had persistently high blood pressure with previous demonstration of various degrees of renal artery lesion on angiography were included into the study. Baseline and captopril scintigraphies were performed on the same day at 4 hour intervals after the injection of 74 and 296 MBq of 99mTc-EC, respectively. All patients had percutaneous transluminal angioplasty (PTA), and improvement in blood pressure was evaluated 3-6 months after the intervention. 99mTc-EC captopril scintigraphy successfully predicted a positive or negative outcome in 11 of 12 patients. In one patient with captopril induced renal function deterioration, scintigraphy failed to predict post-interventional response. Our preliminary findings showed that 99mTc-EC captopril scintigraphy can be used to determine patients who will benefit from revascularization.