Association between cardiovascular inflammation and alterations in immune system induced by HIV infection detected on [18F]FDG PET/MRI.

OBJECTIVE: To assess by [18F]FDG PET/MR the biomarkers of HIV-induced inflammation at baseline and 1 year post-antiretroviral therapy (ART). METHODS: Prospective study, 14 patients, newly diagnosed HIV-positive, asymptomatic. [18F]FDG PET/MRI (PET/MR-3.0T, Signa.GE) whole body and heart was performed, baseline and 1 year post-ART. Qualitative vascular assessment (hepatic reference). Quantitative assessment (SUVmax) of the whole body. T1 and T2 value estimation in 16 myocardial segments. RESULTS: Baseline CMR showed in 3 (21.4%) a decreased LVEF, normalising post-TAR. Fibrosis was ruled out (T1), with no signs of myocardial oedema (T2) at baseline or post-TAR. Four (28.6%) showed baseline vascular [18F]FDG uptake, two in ascending thoracic aorta and two in ascending and descending thoracic aorta, normalising post-TAR. All (100%) showed basal lymph-nodes activity; supra (n:14) and infradiaphragmatic (n:13), laterocervical (n:14) and inguinal (n:13), with variable number of territories (9 patients >6;64.3%). Post-ART, 7 patients (50%) showed resolution and the other 7 reduction in extension (0 patients >5): 7 supra (100%) and 2 infradiaphragmatic (28.6%), 5 in the axilla and 2 in the groin. All (100%) had persistent basal adenoid uptake post-ART, 9 (64.3%) splenic all resolved post-ART and 7 (50.5%) gastric, persistent 3 post-ART. CONCLUSIONS: Cardiovascular biomarkers by [18F]FDG PET/MR have shown baseline 28.6% of patients with large vessel activity and 21.4% with low LVEF, normalising post-ART. Inflammatory/immune biomarkers showed baseline activity in 100% of lymph-nodes, 100% adenoids, 64.3% splenic and 50.5% gastric. Post-TAR the reduction was 50% lymph-nodes, 0% adenoid, 100% splenic and 57.1% gastric.

To evaluate the detection rate of local and whole-body recurrence by integrated [18F]F-PSMA-1007 PET/MR assessment of prostate cancer patients treated with prostatectomy with very low biochemical recurrence (<0.5ng/ml). Therapeutic implications.

OBJECTIVE: To analyse the efficacy of integrated assessment of [18F]F-PSMA-1007 PET/MRI on the early detection of local recurrence (LR) for prostate cancer patients with PSA levels <0.5ng/ml after radical prostatectomy. To assess the location of recurrence so that therapy may be tailored to patient. METHODS: Prospective study including 35 patients with prostate cancer (PCa), who were referred for a [18F]F-PSMA-1007 PET/MR after prostatectomy with a very initial PSA value increase (PSA<0,5ng/ml). Simultaneous acquisition in a PET/MRI hybrid equipment (SIGNA-GE), 1h after administration of 370%±10% MBq of [18F]F-PSMA-1007: Prostate selective imaging (20min): multiparametric PET+MRI (MRImp): DIXON, T1, T2, diffusion sequences post-gadolinium administration. Whole body image (30min): PET+MRI: DIXON, T1, T2, diffusion, STIR sequences. A nuclear physician and a radiologist jointly reviewed the studies: In order to assess LR, the "Prostate Imaging for Recurrence Reporting" system was used on MRI, as well as the Likert scale on the PET prostate imaging. The remaining lesions were classified as N1 and M1a. RESULTS: PET/MRI was positive in 25 patients (71,4%) and negative in 10 patients (28,6%). RL was detected in 15 patients (42.9%): in 2 (5.7%) MRI was superior; in 3 (8.6%) PET was superior; integrated PET/MRI showed improved results in 5 patients (14.3%) for the detection of LR. Location of recurrences: LR in 11 patients (44.0%); N1 in 10 (40.0%); LR+N1 (8.0%) in 2; LR+N1+M1a in 2 (8.0%). In 20 patients (80%) the PET/MRI findings allowed radioguided radiotherapy implementation (11 on LR, and 9 on N1), whereas hormonal treatment was decided in 5 patients (20%) due to multimetastases/spread disease. CONCLUSION: [18F]F-PSMA-1007 PET/MRI has a 71.4% recurrence detection rate after prostatectomy with PSA<0.5ng/ml. Its combined PET and MRI study increases the detection of LR by 14.3%, with a high N1+M1a detection rate (56%), allowing radioguided radiotherapy in 80% of patients.

Detección de la infiltración de la cadena mamaria interna en pacientes con cáncer de mama mediante PET/RM con 18F-FDG y sus implicaciones terapéuticas / Detection of internal mammary chain infiltration in breast cancer patients by [18F]FDG PET/MRI: Therapy implications

Objetivo: Evaluar la tasa de detección y la implicación terapéutica de la infiltración de la cadena mamaria interna (ICMI) mediante tomografía por emisión de positrones (PET) y resonancia magnética (RM) con 18F-fluorodesoxiglucosa (18F-PET/RM) en la estadificación de pacientes con cáncer de mama. Método: Estudio prospectivo, 41 mujeres con cáncer de mama (estadio ≥ IIB) estadificadas mediante 18F-FDG-PET/RM. Estudio en dos fases: imágenes mamarias (decúbito prono), cuerpo completo (supino). Estadificación TNM por consenso entre especialista en Medicina Nuclear y Radiología. Estudio vaso aferente (VA) a cadena mamaria interna (CMI) por RM mamaria. Correlación ICMI con edad, VA-CMI, estadificación T, cuadrante, infiltración axilar y a distancia. Revaloración terapéutica en comité multidisciplinar. Resultados: Tasa de detección de ICMN de 34% (14/41), siendo 8/14 < 55 años. Todas las 14 pacientes con ICMI muestran VA-CMI, en seis de ellas (43,9%) sin VA-axilar. De 27/41 sin ICMI, en 13 (48,1%) solo VA-axilar, en los 14 restantes (51,9%) VA-axilar y VA-CMI. Un total de 57% (8/14) son multicéntricos y 42% (6/14) focales, en cuadrantes internos en 4/6 (66,7%). En 1/14 (7,1%) solo ICMI, en 9/14 (64,3%) axilar y CMI y en 4/14 (28,6%) lesiones a distancia. Decisión del comité: sin tratamiento adicional en 27/41 (65,8%), radioterapia torácica en 10/41 (24,4%) y terapia sistémica en 4/41 (9,7%). Conclusión: La tasa de detección de la ICMI en la estadificación del cáncer de mama mediante 18F-FDG PET/RM es de 34%. Son factores asociados la edad, los tumores multicéntricos, los de cuadrantes internos, la existencia de VA-CMI, la estadificación NM. La evidencia de ICMI permite la individualización de la terapia, indicando la radioterapia torácica en 24,4%.(AU)

Objective: To evaluate the detection rate and therapeutic implication of the infiltration of the internal mammary chain (IMCI) by [18F]FDG PET/MRI for staging of patients with breast cancer. Methods: Prospective study including 41 women with breast cancer (stage ≥IIB) staged by [18F]FDG PET/MR. Two-phase exam: breast imaging (prone), whole-body (supine). TNM stage assessed by peer consensus with Nuclear Medicine and Radiology specialists. Study of the afferent vessel (AV) to IMC by breast MRI. IMCI was correlated with age, AV-IMC, T stage, breast quadrants, axillary and distant infiltration. Therapeutic re-evaluation by a multidisciplinary committee. Results: IMCI detection rate of 34% (14/41), with 8/14 patients under 55 years of age. All 14 patients with IMCI showed AV-IMC, 6 of them (43.9%) without VA-axillary. Of 27/41 patients without IMCI, in 13 (48.1%) only AV-axillary was found, in the remaining 14 (51.9%), AV-axillary and AV-IMC was found. In 57% (8/14) tumours were multicentric and 42% (6/14) focal, in inner quadrants in 4/6 (66.7%). In 1/14 patient (7.1%) only IMCI was found, in 9/14 (64.3%) axillary and IMC, in 4/14 patients (28.6%) distant lesions were detected. Committee re-evaluation: no further treatment in 27/41 patients (65.8%), thoracic radiotherapy in 10/41 patients (24.4%), systemic therapy in 4/41 patients (9.7%). Conclusion: Our detection rate of IMCI in breast cancer staging by [18F]FDG PET/MR was 34%. Related factors were age, multicentric tumours, inner quadrants, detection of AV-IMC, NM staging.The evidence of IMCI allowed tailored therapy, with thoracic radiotherapy implementation in 24.4% of patients.(AU)

Detection of internal mammary chain infiltration in breast cancer patients by [18F]FDG PET/MRI. Therapy implications.

OBJECTIVE: To evaluate the detection rate and therapeutic implication of the infiltration of the internal mammary chain (IMCI) by [18F]FDG PET/MRI for staging of patients with breast cancer. METHODS: Prospective study including 41 women with breast cancer (stage ≥ IIB) staged by [18F]FDG PET/MR. Two-phase exam: breast imaging (prone), whole-body (supine). TNM stage assessed by peer consensus with Nuclear Medicine and Radiology specialists. Study of the afferent vessel (AV) to IMC by breast MRI. IMCI was correlated with age, AV-IMC, T stage, breast quadrants, axillary and distant infiltration. Therapeutic re-evaluation by a multidisciplinary committee. RESULTS: IMCI detection rate of 34% (14/41), with 8/14 patients under 55 years of age. All 14 patients with IMCI showed AV-IMC, 6 of them (43.9%) without VA-axillary. Of 27/41 patients without IMCI, in 13 (48.1%) only AV-axillary was found, in the remaining 14 (51.9%), AV-axillary and AV-IMC was found. In 57% (8/14) tumours were multicentric and 42% (6/14) focal, in inner quadrants in 4/6 (66.7%). In 1/14 patient (7.1%) only IMCI was found, in 9/14 (64.3%) axillary and IMC, in 4/14 patients (28.6%) distant lesions were detected. Committee re-evaluation: no further treatment in 27/41 patients (65.8%), thoracic radiotherapy in 10/41 patients (24.4%), systemic therapy in 4/41 patients (9.7%). CONCLUSION: Our detection rate of IMCI in breast cancer staging by [18F]FDG PET/MR was 34%. Related factors were age, multicentric tumours, inner quadrants, detection of AV-IMC, NM staging. The evidence of IMCI allowed tailored therapy, with thoracic radiotherapy implementation in 24.4% of patients.

Estudio inicial sobre la comparación del rendimiento diagnóstico de la PET/RM con [18F]FDG y la PET/TC con [18F]FDG para la estadificación torácica del cáncer de pulmón de células no pequeñas: enfoque en la invasión pleural / An initial study on the comparison of diagnostic performance of 18F-FDG PET/MR and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer: Focus on pleural invasion

Objetivo Comparar el rendimiento diagnóstico de la PET/RM con [18F]FDG y la PET/TC de forma preliminar en relación con la estadificación torácica del cáncer de pulmón de células no pequeñas (CPCNP) con un enfoque especial en la evaluación de la invasión pleural. Métodos Se incluyeron 52 pacientes con CPCNP con confirmación histopatológica y sometidos a seguimiento durante un año más. Se realizó una PET/TC con [18F]FDG de cuerpo entero y a continuación una PET/RM torácica para la estadificación torácica inicial. Las imágenes de PET/RM torácica se adquirieron simultáneamente e incluyeron secuencias potenciadas en T2, con y sin saturación grasa, en T1 y de difusión. Dos radiólogos evaluaron de forma independiente la estadificación T, N torácica y la afectación pleural. Se utilizó la prueba de Chi-cuadrado de McNemar para comparar las diferencias entre PET/TC y PET/RM en los criterios de evaluación. Se realizó análisis ROC de eficacia diagnóstica con calculó del área bajo la curva (AUC) para el estudio de la invasión pleural. Resultados La PET/RM mostró una mayor sensibilidad y especificidad en la detección de invasión pleural respecto a la PET/TC; 82 vs. 64% (p=0,625), 98 vs. 95% (p=1.000). Los resultados del análisis ROC de la PET/TC vs. la PET/RM respecto a la invasión pleural fueron los siguientes: AUCPET/TC=0,79, AUCPET/RM=0,90, p=0,21. Los resultados de la estadificación T y N fueron casi idénticos en la PET/TC y la PET/RM. Las diferencias existentes entre la PET/TC y la PET/RM para la estadificación T y N y la precisión de la invasión pleural no fueron estadísticamente significativas (p>0,05 en cada una). Conclusión La PET/RM y la PET/TC demostraron un rendimiento equivalente en la evaluación de la estadificación torácica preoperatoria de los pacientes con CPCNP (AU)

Objective To compare the diagnostic performance of 18F-FDG PET/MR and PET/CT preliminarily for the thoracic staging of non-small cell lung cancer (NSCLC) with a special focus on pleural invasion evaluation. Methods Fifty-two patients with pathologically confirmed NSCLC were included and followed for another year. Whole-body 18F-FDG PET/CT and subsequent thoracic PET/MR were performed for initial thoracic staging. Thoracic (simultaneous) PET/MR acquired PET images and MRI sequences including T2 weighted imaging, with and without fat saturation, T1 weighted imaging, and diffusion weighted imaging. Two radiologists independently assessed the thoracic T, N staging and pleural involvement. The McNemar Chi-square test was used to compare the differences between PET/CT and PET/MR in the criteria. The area under the receiver-operating-characteristic curves (AUC) was calculated. Result Compared to PET/CT, PET/MR exhibited higher sensitivity, specificity in the detection of pleural invasion; 82% vs. 64% (P=.625), 98% vs. 95% (P=1.000), PET/MR to PET/CT, respectively. The receiver-operating-characteristic analysis results of PET/CT vs. PET/MR for the pleural invasion were as follow: AUCPET/CT=0.79, AUCPET/MR=0.90, P=.21. Both T staging results and N staging results were approximately identical in PET/CT and PET/MR. Differences between PET/CT and PET/MR in T staging, N staging as well as pleural invasion accuracy were not statistically significant (P>.05, each). Conclusion PET/MR and PET/CT demonstrated equivalent performance about the evaluation of preoperative thoracic staging of NSCLC patients. PET/MR may have greater potential in pleural invasion evaluation for NSCLC, especially for solid nodules, crucial to clinical decision-making, though our results did not demonstrate statistical significance (AU)

An initial study on the comparison of diagnostic performance of 18F-FDG PET/MR and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer: Focus on pleural invasion.

OBJECTIVE: To compare the diagnostic performance of 18F-FDG PET/MR and PET/CT preliminarily for the thoracic staging of non-small cell lung cancer (NSCLC) with a special focus on pleural invasion evaluation. METHODS: 52 patients with pathologically confirmed NSCLC were included and followed for another year. Whole-body 18F-FDG PET/CT and subsequent thoracic PET/MR were performed for initial thoracic staging. Thoracic (simultaneous) PET/MR acquired PET images and MRI sequences including T2 weighted imaging, with and without fat saturation, T1 weighted imaging, and diffusion weighted imaging (DWI). Two radiologists independently assessed the thoracic T, N staging and pleural involvement. The McNemar Chi-square test was used to compare the differences between PET/CT and PET/MR in the criteria. The area under the receiver-operating-characteristic curves (AUC) was calculated. RESULTS: Compared to PET/CT, PET/MR exhibited higher sensitivity, specificity in the detection of pleural invasion; 82 % vs. 64% (p = 0.625), 98 % vs. 95% (p = 1.000), PET/MR to PET/CT respectively. The receiver-operating-characteristic analysis results of PET/CT vs PET/MR for the pleural invasion were as follow: AUCPET/CT = 0.79, AUCPET/MR = 0.90, p = 0.21. Both T staging results and N staging results were approximately identical in PET/CT and PET/MR. Differences between PET/CT and PET/MR in T staging, N staging as well as pleural invasion accuracy were not statistically significant (p > 0.05, each). CONCLUSION: PET/MR and PET/CT demonstrated equivalent performance about the evaluation of preoperative thoracic staging of NSCLC patients. PET/MR may have greater potential in pleural invasion evaluation for NSCLC, especially for solid nodules, crucial to clinical decision-making, though our results did not demonstrate statistical significance.

Valor adicional de la tecnología híbrida de PET/RM frente a la RM y la PET en la enfermedad cardiovascular / Additional value of hybrid PET/MR imaging versus MR or PET performed separately to assess cardiovascular disease

Introducción y objetivos Los sistemas híbridos de tomografía por emisión de positrones (PET) y resonancia magnética (RM) son una tecnología prometedora para el diagnóstico por imagen, pero su aplicación cardiovascular en nuestro entorno clínico es desconocida. Nuestro objetivo es evaluar el valor de los equipos integrados de PET/RM frente a la RM y la PET por separado. Métodos Se incluyó prospectivamente a 49 pacientes, 30 para valoración de viabilidad miocárdica (grupo coronario) y 19 para estudio de enfermedad inflamatoria, infecciosa y tumoral (grupo no coronario), a los que se realizó una PET/RM cardiaca con 18F-fluorodesoxiglucosa, incluyendo secuencias de corrección de atenuación y, simultáneamente a la PET, secuencias de cine, caracterización tisular o realce tardío de RM, según indicación clínica. Resultados El 87,8% de los estudios de PET/RM fueron inicialmente interpretables. La PET/RM mejoró el diagnóstico en el 42,1% de los pacientes del grupo coronario respecto a la PET o la RM por separado, y en el 88,9% del grupo no coronario. De los casos no concluyentes según la RM o la PET, la PET/RM reclasificó a estudio diagnóstico al 87,5% de los pacientes del grupo coronario y el 70% de los del no coronario. Conclusiones En nuestra serie, la tecnología multimodal de PET/RM añade valor diagnóstico en algunos pacientes con enfermedad cardiovascular, sobre todo en enfermedad no coronaria y con hallazgos no concluyentes por RM o PET, y complementa cada técnica por separado. Los principales beneficios incluyen la adquisición simultánea, la integración de imágenes anatómicas, funcionales y metabólicas y la interacción entre distintos profesionales expertos en imagen. (AU)

Introduction and objectives Hybrid positron emission tomography (PET) and magnetic resonance (MR) imaging is an emerging technology in the diagnosis of cardiovascular disease; however, there have been no reports of its use in the national clinical setting. Our objective was to evaluate the additional value of integrated PET/MR systems compared with MR and PET performed separately in this setting. Methods We prospectively included 49 patients, 30 to assess myocardial viability (coronary group) and 19 to assess inflammatory, infectious, and tumoral diseases (noncoronary heart disease group). All patients underwent cardiac 18F-fluorodeoxyglucose PET/MR. PET/MR studies included attenuation correction sequences, followed by simultaneous cardiac PET and cardiac MR acquisition, with protocols adapted to the clinical indication (cine, tissue characterization and/or late enhancement imaging). Results Most (87.8%) PET/MR studies were initially interpretable. Use of PET/MR improved diagnosis vs PET or MR performed separately in 42.1% of coronary cases and 88.9% of noncoronary cases. PET/MR enabled reclassification of 87.5% of coronary cases initially classified as showing inconclusive results on MR or PET and 70% of noncoronary cases. Conclusions In our series, multimodality PET/MR technology provided additional diagnostic value in some patients with cardiovascular disease compared with MR and PET performed separately, especially in cases of noncoronary heart disease and in those with inconclusive results on MR or PET. In our experience, the main benefits of PET/MR include the possibility of simultaneous acquisition, the in vivo integration of anatomical/functional/metabolic aspects, and the interaction of different experts in imaging modalities. (AU)

18F-choline PET/MRI on initial staging of prostate cancer. Impact on therapy approach. / La PET/RM con 18F-colina en el diagnóstico inicial del cáncer de próstata. Impacto en la estrategia terapéutica.

AIM: Evaluate the therapy impact of initial staging in patients diagnosed with prostate cancer by 18 F-choline PET/MRI hybrid technique. MATERIAL: A prospective study which included 31 patients diagnosed with prostate cancer; Gleason > 7; mean PSA 13.6 ng/mL (range 6.3-20.6). PET/MRI studies were acquired simultaneously with hybrid equipment (SIGNA.3T, GE) following intravenous injection of 185 ± 18.5MBq of 18F-choline: - Early/prostate imaging: PET emission + multiparametric MR: DIXON-T1-T2-diffusion-gadolinium. - Late/whole-body imaging: PET emission + MR: DIXON-T1-T2-diffusion-STIR sequences. Images were visually evaluated. SUV & ADC & textures were also calculated. Treatment selection was based upon Oncology Committee consensus decision. RESULTS: Procedure was well tolerated in all patients, and no artifacts were reported. MRI was superior in T staging in eight patients (25.8%) (Likert: 2-3), whereas PET increased MRI sensitivity in three patients (9.7%) (PIRADS: 3). PROSTATE LESION LOCATION: Peripheral 91.4%, transitional 8.6%. SUVmax threshold: 2.95: sensitivity 92.9%, specificity 66.7%. No correlation SUV vs. ADC. Better distinction between stage T2 vs. T3 using the DiscrLin model with NG = 16 (AUC 0.7767 ± 0.3386). PET was superior to T2 in textures analysis (0.588 vs. 0.412). Seventeen patients (54.8%) were staged ≥ T3, with surgical treatment being contraindicated. Fifteen patients (48.4%) presented with extra-prostatic disease: 8/31 oligometastatic and 7/31 multiple metastasis. Therapy approach following PET/MRI was: radical treatment in 24/31 patients (77.4%), 14 radical prostatectomy and 10 MRI-guided radiotherapy; systemic treatment in 7/31 patients (22.6%). CONCLUSION: 18F-choline PET/MRI had a complementary role for the T staging, with a high detection rate for NM infiltration. PET/MRI findings allowed patients to be directed either to prostatectomy or MRI-guided radiotherapy, and thus avoiding radicaltreatment in 22.6% of patients.

Additional value of hybrid PET/MR imaging versus MR or PET performed separately to assess cardiovascular disease.

INTRODUCTION AND OBJECTIVES: Hybrid positron emission tomography (PET) and magnetic resonance (MR) imaging is an emerging technology in the diagnosis of cardiovascular disease; however, there have been no reports of its use in the national clinical setting. Our objective was to evaluate the additional value of integrated PET/MR systems compared with MR and PET performed separately in this setting. METHODS: We prospectively included 49 patients, 30 to assess myocardial viability (coronary group) and 19 to assess inflammatory, infectious, and tumoral diseases (noncoronary heart disease group). All patients underwent cardiac 18F-fluorodeoxyglucose PET/MR. PET/MR studies included attenuation correction sequences, followed by simultaneous cardiac PET and cardiac MR acquisition, with protocols adapted to the clinical indication (cine, tissue characterization and/or late enhancement imaging). RESULTS: Most (87.8%) PET/MR studies were initially interpretable. Use of PET/MR improved diagnosis vs PET or MR performed separately in 42.1% of coronary cases and 88.9% of noncoronary cases. PET/MR enabled reclassification of 87.5% of coronary cases initially classified as showing inconclusive results on MR or PET and 70% of noncoronary cases. CONCLUSIONS: In our series, multimodality PET/MR technology provided additional diagnostic value in some patients with cardiovascular disease compared with MR and PET performed separately, especially in cases of noncoronary heart disease and in those with inconclusive results on MR or PET. In our experience, the main benefits of PET/MR include the possibility of simultaneous acquisition, the in vivo integration of anatomical/functional/metabolic aspects, and the interaction of different experts in imaging modalities.

Importance of attenuation correction in PET/MR image quantification: Methods and applications. / Importancia de la corrección de atenuación en la cuantificación de imagen PET/RM: métodos y aplicaciones.

The generation of accurate attenuation correction (AC) maps is a basic step to allow for quantitative PET/MR imaging. However, generating MR-based AC maps is a challenge because there is no direct relationship between the PET attenuation coefficients (µ) and the intensity of the MR signal, contrary to what happens with the intensity of CT images. In fact, ignoring the bone causes a distorted and biased distribution of the calculated SUV values. To solve this problem, several MR-based AC methods have been proposed in the literature. In this paper we describe how these methods work, and the challenge they faced to translate into full body applications. Currently, in research environments, the accuracy of AC methods is no longer a limiting factor to solve in order to carry out quantitative in vivo molecular imaging studies. However, many of these methods present a series of limitations for their real implementation in the clinical practice due to insufficient clinical validation and the difficulty of their implementation in a real environment (as described in the examples of clinical applications). Thus, we need the PET/MR community to work on the standardization of the use and assessment of different AC methods. In this scenario, the opening and access by vendors to the implementation of new AC methods in their PET/MR scanners plays a crucial role.

Value of 18F-Choline PET/MRI hybrid technique on the therapeutic approach for patients with prostate cancer treated with prostatectomy and rising prostate specific antigen levels below 1 ng/ml. / Impacto de la tecnología híbrida PET/RM con 18F-colina en la estrategia terapéutica de los pacientes con cáncer de próstata tratados con prostatectomía que presentan elevación del antígeno prostático específico inferior a 1 ng/ml.

OBJECTIVE: To assess the detection rate of 18F-Choline PET/MRI and subsequent changes in therapy approach for patients with prostate cancer treated by prostatectomy and with rising levels of PSA <1 ng/ml. METHODS: Prospective study with our first 36 patients with prostatectomy for prostate cancer and rising levels of PSA, who were referred for an 18F-Choline PET/MRI study. A dual-phase study was acquired after intravenous administration of 185±10% MBq of 18F-Choline: 1) early imaging (immediately after tracer administration) of prostate area (emission PET/Multiparametric MRI). 2) whole-body imaging 1 h after tracer injection (emission PET/MRI: T1, T2, STIR, diffusion). The therapy approach for patients was decided upon the Oncology Committee consensus based on 18F-Choline PET/MRI findings. RESULTS: Twenty out of 36 patients (55.6%) were positive for the 18F-Choline PET/MRI study: 8 (22.2%) within the prostatectomy bed, 7 (19.4%) with infradiaphragmatic lymph nodes, 4 (11.1%) with local recurrence and infradiaphragmatic lymph nodes, and 1 (2.8%) with bone metastasis. Sixteen out of the 36 patients (44.4%) were negative for the 18F-Choline PET/MRI study. 18F-Choline PET/MRI findings had an impact on the therapy approach to follow: 15 patients (41.6%) showed oligometastatic disease which was treated by imaging-guided radiotherapy, 5 (13.9%) with multiple metastatic disease were treated by androgen deprivation therapy, 16 (44.4%) negative were under active surveillance. CONCLUSION: Hybrid 18F-Choline PET/MRI procedure showed a high detection rate for recurrence in prostate cancer patients treated with prostatectomy and rising PSA levels <1 ng/ml, and 18F-Choline PET/MRI findings resulted in a better tailored therapy approach delivered to our patients.

18F-choline PET/MRI in suspected recurrence of prostate carcinoma. / PET/RM con 18F-colina en la sospecha de recurrencia del carcinoma de próstata.

OBJECTIVE: To evaluate the usefulness of simultaneous 18F-choline PET/MRI in the suspicion of prostate cancer recurrence and to relate 18F-choline PET/MRI detection rate with analytical and pathological variables. MATERIAL AND METHODS: 27 patients with prostate cancer who received local therapy as primary treatment underwent a 18F-choline PET/MRI due to suspicion of recurrence (persistently rising serum PSA level). 18F-choline PET/MRI findings were validated by anatomopathological analysis, other imaging tests or by biochemical response to oncological treatment. RESULTS: 18F-choline PET/MRI detected disease in 15 of 27 patients (detection rate 55.56%). 4 (15%) presented exclusively local recurrence, 5 (18%) lymph node metastases and 7 (26%) bone metastases. Mean PSA (PSAmed) at study time was 2.94ng/mL (range 0.18-10ng/mL). PSAmed in patients with positive PET/MRI was 3.70ng/mL (range 0.24-10ng/mL), higher than in patients with negative PET/MRI, PSAmed 1.97ng/mL (range 0.18-4.38ng/mL), although without statistically significant differences. Gleason score at diagnosis in patients with a positive study was 7.33 (range 6-9) and in patients with a negative study was 7 (range 6-9), without statistically significant differences. CONCLUSION: 18F-choline PET/MRI detection rate was considerable despite the relatively low PSA values in our sample. The influence of Gleason score and PSA level on 18F-choline PET/MRI detection rate was not statistically significant.

Hybrid imaging in foot and ankle disorders. / Imagen híbrida en la patología del pie y tobillo.

Disorders of the foot and ankle are some of the most frequent ones affecting the musculoskeletal system and have a great impact on patients' quality of life. Accurate diagnosis is an important clinical challenge because of the complex anatomy and function of the foot, that make it difficult to locate the source of the pain by routine clinical examination. In the study of foot pathology, anatomical imaging (radiography, magnetic resonance imaging [MRI], ultrasound and computed tomography [CT]) and functional imaging (bone scan, positron emission tomography [PET] and MRI) techniques have been used. Hybrid imaging combines the advantages of morphological and functional studies in a synergistic way, helping the clinician manage complex problems. In this article we delve into the anatomy and biomechanics of the foot and ankle and describe the potential indications for the current hybrid techniques available for the study of foot and ankle disease.

The effect of tissue-segmented attenuation maps on PET quantification with a special focus on large arteries. / Efecto de la segmentación por tejidos en los mapas de atenuación sobre la cuantificación PET con especial hincapié en grandes arterias.

OBJECTIVES: Accuracy on quantitative PET image analysis relies on the correct application of attenuation correction which is one of the major challenges for PET/MRI that remains to be solved. The purpose of this study is to evaluate the effect of MRI-based attenuation maps and the use of flexible coils on the quantitative accuracy of PET images with a special focus on large arteries. MATERIALS AND METHODS: PET/CT data from eight oncologic patients was used. PET data was reconstructed using attenuation maps with different level of detail emulating several approaches available on current PET/MRI scanners. PET images obtained with CT-based and MRI-based attenuation maps were compared to evaluate the quantitative biases obtained. The quantitative effect produced by flexible MRI receiver coils on the attenuation maps was also studied. RESULTS: The use of simpler attenuation maps produced increased biases between PET data reconstructed with CT-based and MRI-based attenuation maps for fat, non-fat soft-tissues and bone. Biases in lung were very high due to the large heterogeneity and inter-patient variability of the lung. The quantification on large arteries had small deviations except for the case when flexible coils were used. The TBR provided smaller biases in all cases as it cancelled out the similar deviations obtained for arteries and reference veins. CONCLUSIONS: Simplified attenuation maps used on PET/MRI significantly increase the quantitative variability of PET images especially on lungs and bones. The quantification of PET images acquired with PET/MRI scanners applied to studies of atherosclerosis has small deviations, especially when the TBR is considered.

Simultaneous PET/MRI vs PET/CT in oncology. A systematic review. / PET/RM simultánea vs. PET/TC en oncología. Una revisión sistemática.

OBJECTIVE: The aim of this review was to evaluate the diagnostic performance of simultaneous PET/MRI in oncology compared with that of PET/CT, based upon the available evidence. MATERIAL AND METHODS: A systematic search was performed in the Medline and Embase databases to identify original clinical articles published up to 21 January 2016, in order to compare simultaneous PET/MRI and PET/CT in oncology patients. RESULTS: A total of 57 articles were obtained that included various diseases: head and neck cancer (5), lung cancer and lung nodules (13), colorectal cancer (1), liver lesions (2), abdominal incidentalomas (1), neuroendocrine tumours (2), thyroid carcinoma (2), breast cancer (3), gynaecological cancer (2), prostate cancer (4), lymphoma (2), multiple myeloma (1), bone metastases (3), intracranial tumours (2), paediatric oncology (1) and various tumours (13). Diagnostic performance of simultaneous PET/MRI was similar or even better to that of PET/CT in most oncological diseases. However, PET/CT was superior for small lung nodule detection. CONCLUSION: Simultaneous PET/MRI in oncology is feasible, performing at least equally as well as PET/CT, with lower radiation exposure. However, available evidence is still limited. Studies including more patients and tumours are needed to establish PET/MRI indications and to identify appropriate protocols for each disease.

PET/MRI: A luxury or a necessity? / PET/RM: ¿un lujo o una necesidad?

PET/MRI is a new multimodality technique with a promising future in diagnostic imaging. Technical limitations are being overcome. Interference between the two systems (PET and MRI) seems to have been resolved. MRI-based PET attenuation correction can be performed safely. Scan time is acceptable and the study is tolerable, with claustrophobia prevalence similar to that of MRI. Quantification with common parameters, such as Standardized Uptake Value (SUV), shows a fairly good correlation between both systems. However, PET/CT currently provides better results in scan time, scan costs, and patient comfort. Less patient radiation exposure is a big advantage of PET/MRI over PET/CT, which makes it particularly recommended in paediatric and adolescent patients requiring one or more studies. PET/MRI indications are the same as those of PET/CT, given that in cases where MRI is superior to CT, PET/MRI is superior to PET/CT. This superiority is clear in many soft tissue tumours. Moreover, it is common to perform both PET/CT and MRI in neurological diseases, as well as in some tumours, such as breast cancer. A single PET/MRI study replaces both with obvious benefit. MRI also allows other MRI-based PET corrections, such as motion or partial volume effect corrections. The better spatial resolution of MRI allows the transfer of well-defined MRI areas or small volumes of interest to PET image, in order to measure PET biomarkers in these areas. The richness of information of both techniques opens up immense possibilities of synergistic correlation between them.

[Nuclear medicine and radiopharmaceuticals]. / Medicina nuclear y radiofármacos.

Nuclear Medicine is a medical specialty that allows modern diagnostics and treatments using radiopharmaceuticals original radiotracers (drugs linked to a radioactive isotope). In Europe, radiopharmaceuticals are considered a special group of drugs and thus their preparation and use are regulated by a set of policies that have been adopted by individual member countries. The radiopharmaceuticals used in diagnostic examinations are administered in very small doses. So, in general, they have no pharmacological action, side effects or serious adverse reactions. The biggest problem associated with their use are the alterations in their biodistribution that may cause diagnostic errors. Nuclear Medicine is growing considerably influenced by the appearance and development of new radiopharmaceuticals in both the diagnostic and therapeutic fields and primarily to the impact of new multimodality imaging techniques (SPECT-CT, PET-CT, PET-MRI, etc.). It's mandatory to know the limitations of these techniques, distribution and eventual physiological alterations of radiopharmaceuticals, contraindications and adverse reactions of radiological contrasts, and the possible interference of both.

Evaluación del corregistro de imágenes de resonancia magnética y tomografía por emisión de positrones con 2-desoxy-2-flúor-d-glucosa marcada con flúor-18 en pacientes con patología tumoral cerebral / Validation of MRI and 18F-FDG-PET coregistration in patients with primary brain tumors

Objetivo: Determinar la efectividad del co-registro de imágenes PET/RM (tomografía de emisión de positrones y resonancia magnética) en el diagnóstico de recidiva tumoral vs.. radionecrosis en pacientes con patología tumoral cerebral primaria previamente tratados. Material y métodos: El diagnóstico de tumor cerebral se determinó por RM e histopatología. Después de 3 a 5 meses postratamiento se realizó RM y PET como parte del seguimiento. El análisis de dichas imágenes se hizo de manera visual y semicuantitativa mediante la obtención de un índice de captación de 18F-FDG de tejido tumoral/ tejido cerebral sano. Resultados: Se estudiaron 57 pacientes; un total de 37 gliomas astrocíticos, 9 gliomas mixtos, 5 tumores embrionarios, 1 tumor meníngeo y 1 tumor oligodendroglial . Todas las imágenes de RM presentaban áreas de reforzamiento, dejando sospecha entre radionecrosis o viabilidad tumoral; con el co-registro PET/RM se diagnosticaron 21 estudios negativos (30 %) y 36 positivos (70 %). El índice tejido tumoral/tejido cerebral sano se correlacionó adecuadamente con los resultados visuales obtenidos. Conclusión: La RM sobreestima el área tumoral a valorar. La presencia de la actividad metabólica analizada mediante PET sobre las áreas de reforzamiento por RM permite determinar la presencia de viabilidad tumoral. Esto aumenta la certeza diagnóstica de ambas técnicas de imagen.

OBJECTIVE: To evaluate the role of PET and MRI fused image study inpatients with primary brain tumors previously treated, to determine the presence of radionecrosis vs residual tumor viability. METHODS: Primary brain tumors were diagnosed by biopse and MR. 18FDG-PET scan and T1 enhanced MRI follow-up studies were performed between 3 and 5 months after treatment. The 18F-FDG uptake was semiquantitavively calculated by a region-of-interest based Tumor hotspot/normal brain tissue index. RESULTS: Fifty-seven patients were studied, 37 had high grade gliomas; 9 had oligoastrocytomas; 5 had Embrionary tumors; I had a meningyoma and I had an oliodendroglial tumor. All MR studies showed tumor enhancement, without determine wether if it was radionecrosis or tumor viability. PET/MR fused study diagnosed 21 negative studies (30%) and 36 positive results (70%). Tumor hotspot/normal brain tissue index correlated well with the visual analysis registered. CONCLUSIONS: Visual analysis in the contrast enhanced MR overestimates the tumoral area, without defining a possible diagnosis between tumor viability and radionecrosis. Metabolic activity in the 18F-FDG PET study in the enhanced area, determines the presence of residual tumor viability. Therefore, coregistration can be used to obtain a more specific diagnosis optimizing the cinical use.