Estudio comparativo de la sensibilidad del MAMMI-PET en el diagnóstico de cáncer de mama con respecto a otras pruebas de imagen / Comparative study of the sensitivity of MAMMI-PET in the diagnosis of breast cancer with regard to other imaging tests

Introducción: el empleo de dispositivos de tomografía por emisión de positrones mamodedicados (dbPET) mejora la resolución espacial respecto a la PET corporal total. La mamografía mediante imagen molecular PET (MAMMI-PET) es una nueva técnica, pero los estudios clínicos realizados son escasos. El objetivo del trabajo es determinar la sensibilidad, especificidad, los valores predictivos positivos y negativos de la MAMMI-PET, así como comparar el dispositivo con las pruebas de imagen tradicionales. Material y métodos: estudio observacional prospectivo y analítico sobre una muestra de pacientes con cáncer de mama confirmado histológicamente, atendidas en el Hospital General de Valencia (enero 2017-noviembre 2018). Se realizó un estudio preoperatorio con ecografía, mamografía, resonancia magnética nuclear y MAMMI-PET. Se consideró a la anatomía patológica como el patrón oro del número y tipo de lesiones existentes en cada mama. Se comprobó si el diagnóstico del MAMMI-PET para cada lesión coincidió con el resultado de la anatomía patológica. Se comparó la sensibilidad de cada prueba con la del MAMMI-PET empleando la prueba de Chi cuadrado con nivel de significación de 0,05. Resultados: se evaluaron los datos de 32 pacientes y 44 lesiones (36 malignas y 8 benignas). Dos pacientes fueron excluidas del estudio. Se obtuvo una sensibilidad del 75% para el MAMMI-PET. La mejor sensibilidad se obtuvo para la resonancia magnética nuclear con 85,3% mientras que para la ecografía y la mamografía fue de 77,8 y 69,4%, respectivamente. No se evidenciaron diferencias estadísticamente significativas en el estudio comparativo entre el MAMMI-PET y el resto de las pruebas de imagen. Conclusiones: la sensibilidad del MAMMI-PET (75%) para el diagnóstico de cáncer de mama fue similar a las otras pruebas de imagen. (AU)

Introduction: The use of mammo dedicated breast PET (dbPET) scanners improves spacial resolution compared to Whole Body Pet images (WBPET). Mammography with Molecular Imaging PET (MAMMI-PET) is a new device with hardly any clinical studies. The aim of the study is to estimate the sensitivity of MAMMI-PET and compare it with classic imaging devices. Material and methods: A prospective and analytical observational study was carried out in a sample of patients with histologically confirmed breast cancer who were treated at our hospital between January 2017 and November 2018. Preoperative study of patients was performed with ultrasound, mammography, Magnetic Resonance Imaging (MRI) and MAMMI-PET. Findings (number and benignant/malignant lesions) of the anatomopathological (AP) study were used as the gold standard. Results between MAMMI-PET and AP were compared. The sensitivity of each test was compared with that of the MAMMI-PET using the Chi square test with a significance level of 0.05. Results: Data from 32 patients and 44 lesions (36 malignant and 8 benign) were evaluated. Two patients were excluded. The MAMMI-PET sensitivity was 75%. The best sensitivity was obtained for MRI with 85.3%, while for ultrasound and mammography it was 77.8% and 69.4% respectively. No statistically significant differences were found between the sensitivity of MAMMIPET and the rest of the imaging tests. Conclusions: The sensitivity obtained for the MAMMI-PET scanner (75%) was similar to the other imaging tests. (AU)

Correlation between MAMMI-PET findings and anatomopathological outcomes in breast cancer patients.

OBJECTIVE: Imaging tests are a key element in the preoperative diagnosis of patients with breast cancer. Whole-body PET-computed tomography (PET/CT) breast studies have a limited spatial resolution, although dedicated breast PET (dbPET) devices such as the Mammography with Molecular Imaging PET (MAMMI-PET), have an increased sensitivity to detect tumor foci, especially those smaller than 2 cm. The purpose of this study is to define the validity and reliability of this new device. METHODS: A prospective and analytical observational study was carried out in a sample of patients with histologically confirmed breast cancer who were treated at our hospital between January 2017 and November 2018. The anatomopathological study findings for the surgical pieces were used as gold standards and we calculated their concordance with the findings from the MAMMI-PET as well as the validity and reliability parameters for this test. RESULTS: Data from 32 patients and 44 lesions (36 malignant and 8 benign) were evaluated. The mean patient age was 51.50 ± 11.68 years. Twenty patients had received neoadjuvant chemotherapy (NACT). The technique concordance rate was weak ( K = 0.349, P = 0.001) and was 84.3% for benign lesions and 62.6% for malignant ones. The MAMMI-PET sensitivity was 75%, whereas its specificity was 57.1%; the positive predictive value was 81.8% and the negative predictive value was 47.1%, with an overall precision of 70%. The MAMMI-PET sensitivity was higher in patients who had not undergone NACT and was significantly higher in patients with luminal B breast cancer compared to the luminal A subtype. CONCLUSION: The MAMMI-PET device had acceptable sensitivity and a high positive predictive value for the preoperative evaluation of patients with breast cancer; it was especially useful for lesions whose diagnosis with other imaging tests had been doubtful.

Performance evaluation of a high resolution dedicated breast PET scanner.

PURPOSE: Early stage breast cancers may not be visible on a whole-body PET scan. To overcome whole-body PET limitations, several dedicated breast positron emission tomography (DbPET) systems have emerged nowadays aiming to improve spatial resolution. In this work the authors evaluate the performance of a high resolution dedicated breast PET scanner (Mammi-PET, Oncovision). METHODS: Global status, uniformity, sensitivity, energy, and spatial resolution were measured. Spheres of different sizes (2.5, 4, 5, and 6 mm diameter) and various 18 fluorodeoxyglucose ((18)F-FDG) activity concentrations were randomly inserted in a gelatine breast phantom developed at our institution. Several lesion-to-background ratios (LBR) were simulated, 5:1, 10:1, 20:1, 30:1, and 50:1. Images were reconstructed using different voxel sizes. The ability of experienced reporters to detect spheres was tested as a function of acquisition time, LBR, sphere size, and matrix reconstruction voxel size. For comparison, phantoms were scanned in the DbPET camera and in a whole body PET (WB-PET). Two patients who just underwent WB-PET/CT exams were imaged with the DbPET system and the images were compared. RESULTS: The measured absolute peak sensitivity was 2.0%. The energy resolution was 24.0% ± 1%. The integral and differential uniformity were 10% and 6% in the total field of view (FOV) and 9% and 5% in the central FOV, respectively. The measured spatial resolution was 2.0, 1.9, and 1.7 mm in the radial, tangential, and axial directions. The system exhibited very good detectability for spheres ≥4 mm and LBR ≥10 with a sphere detection of 100% when acquisition time was set >3 min/bed. For LBR = 5 and acquisition time of 7 min the detectability was 100% for spheres of 6 mm and 75% for spheres of 5, 4, and 2.5 mm. Lesion WB-PET detectability was only comparable to the DbPET camera for lesion sizes ≥5 mm when acquisition time was >3 min and LBR > 10. CONCLUSIONS: The DbPET has a good performance for its clinical use and shows an improved resolution and lesion detectability of small lesions compared to WB-PET.

Limbic Encephalitis Diagnosed With 18F-FDG PET/CT.

Limbic encephalitis is a subacute onset syndrome characterized by short-term memory impairment, confusion, temporal lobe epilepsy, hypothalamic dysfunction, and psychiatric symptoms. Common causes are autoimmune disorders or idiopathic disease, although it has been associated to tumors. We report the case of a woman arrived at the emergency department having had fluctuating impaired memory for 2 weeks. The first MRI was normal. It was decided to perform lumbar puncture and PET/CT to exclude viral origin or paraneoplastic syndrome. Typical abnormalities were found in the second MRI (1 month after previous); however, FDG PET is a useful tool that contributes to early detection.

Whole-body PET/CT studies with lowered ¹8F-FDG doses: the influence of body mass index in dose reduction.

UNLABELLED: The administered dose of (18)F-FDG can be greatly reduced using body mass index (BMI) instead of the patient's weight, without diminishing image quality. We have focused on reducing the administered dose while maintaining the acquisition time and have developed dosing-based algorithms using BMI. We conducted a prospective dose-adjustment research study with more than 1,800 patients undergoing time-of-flight PET/CT. METHODS: From January 2009 to October 2010 we recruited 1,000 patients, of whom 180 were randomly selected to create the control group. The treatment group was created by selecting 180 new subjects from a total of 800 recruited from January to December 2011. The control group was administered a body weight-calculated dose of 5.55-7.4 MBq/kg. The treatment group was administered a BMI-calculated dose of 6.85-11.1 MBq/BMI. Each group was divided into 5 subgroups according to BMI classification (underweight, normal weight, overweight, obese, and morbidly obese). All scans were acquired with a time-of-flight PET/CT scanner and were evaluated in a masked manner by 2 nuclear medicine physicians. Evaluation of images was purely qualitative, with visual scoring of image quality from 1 to 3 (high to low). These data were analyzed for statistical significance. Dosimetric measures of patients' emitted radiation were taken at the surface and at a distance of 0.5 m and 1 m to compare the groups. The readings of PET staff dosimeters were evaluated during this period and analyzed. RESULTS: A reduction of between 9% and 22% in administered dose per patient was achieved for the BMI-derived dose group with respect to the body weight-calculated dose group. In addition, an effective dose reduction of 56% and 12.5% for patients and staff, respectively, was achieved. The cost per study was therefore reduced while diagnostic image quality was maintained or even improved in most cases. CONCLUSION: BMI-calculated doses, which are often lower than strictly weight-based doses, can be administered while maintaining acquisition times. This dose reduction is not only consistent with the as-low-as-reasonably-achievable principle but can be performed without diminishing diagnostic accuracy and should lead to lower dose to staff and potential economic savings.

Empleo de un agente oral efervescente en el diagnóstico del cáncer gástrico mediante PET-TAC con 18F-FDG / Use of an oral effervescent agent in the diagnostic of gastric carcinoma with 18F-FDG PET/CT

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