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Objectives To determine the value of 18F-FDG-PET/MRI in the diagnosis and management of patients with pelvic recurrence of rectal cancer. Methods Forty-four patients (16 women, 28 men) with a history of rectal cancer who received FDG-PET/MRI between June 2011 and February 2017 at our institution were retrospectively enrolled. Three patients received two FDG-PET/MRIs; thus a total of 47 examinations were included. Pelvic recurrence was confirmed either with histology (n = 27) or imaging follow-up (n = 17) (> 4 months). Two readers (one radiologist, one nuclear medicine physician) interpreted the images in consensus. Pelvic lesions were assessed regarding FDG uptake and morphology. Sensitivity, specificity, positive and negative predictive values as well as accuracy of PET/MRI in detecting recurrence were determined. Results In 47 FDG-PET/MRIs 30 suspicious pelvic lesions were identified, 29 of which were malignant. Two patients underwent resection and had histologically proven pelvic recurrence without showing suspicious findings on FDG-PET/MRI. Changes in management due to FDG-PET/MRI findings had been implemented in eight patients. Eighty per cent (16/20) of resected patients had histologically negative resection margins (R0), one patient had uncertain resection margins. Sensitivity of FDG-PET/MRI in detecting recurrence was 94%, specificity 94%, positive/negative predictive value and accuracy were 97%, 90% and 94%, respectively. Conclusions FDG-PET/MRI is a valuable tool in the diagnosis and staging of pelvic recurrence in patients with rectal cancer.

Objective To assess the diagnostic value of PET/MR (positron emission tomography/magnetic resonance imaging) with FDG (18F-fluorodeoxyglucose) for lymph node staging in head and neck cancer. Materials and Methods This prospective study was approved by the local ethics committee; all patients signed informed consent. Thirty-eight patients with squamous cell carcinoma of the head and neck region underwent a PET scan on a conventional scanner and a subsequent PET/MR on a whole-body hybrid system after a single intravenous injection of FDG. The accuracy of PET, MR and PET/MR for lymph node metastases were compared using receiver operating characteristic (ROC) analysis. Histology served as the reference standard. Results Metastatic disease was confirmed in 16 (42.1%) of 38 patients and 38 (9.7%) of 391 dissected lymph node levels. There were no significant differences between PET/MR, MR and PET and MR (p > 0.05) regarding accuracy for cervical metastatic disease. Based on lymph node levels, sensitivity and specificity for metastatic involvement were 65.8% and 97.2% for MR, 86.8% and 97.0% for PET and 89.5% and 95.2% for PET/MR. Conclusions In head and neck cancer, FDG PET/MR does not significantly improve accuracy for cervical lymph node metastases in comparison to MR or PET.

Rationale and Objectives: The purpose of this study was to evaluate the sensitivity and specificity of positron emission tomography/magnetic resonance imaging (PET/MR) with 18F-fluorodeoxyglucose (FDG) for nodal involvement in malignant lymphoma. Materials and Methods: Twenty-seven patients with malignant lymphoma (16 men and 11 women; mean age, 45 years) were included in this retrospective study. The patients underwent FDG PET/MR after intravenous injection of FDG (176-357 MBq FDG, 282 MBq on average). Follow-up imaging and histology served as the standard of reference. Results: One-hundred and twenty-seven (18.1%) of 702 lymph node stations were rated as having lymphoma-involvement based on the standard of reference. One-hundred and twenty-four (17.7%) of 702 lymph node stations were rated as positive by FDG PET/MR. The sensitivity and specificity of FDG PET/MR for lymph node station involvement were 93.8% and 99.4%. Conclusions: FDG PET/MR is feasible for lymphoma staging and has a high-sensitivity and specificity for nodal involvement in lymphoma. Comparison with PET/CT is necessary to determine whether FDG PET/MR can replace PET/CT for lymphoma staging.

Object: To evaluate the feasibility of positron emission tomography/magnetic resonance imaging (PET/MR) with 18fluoro-2-deoxyglucose (FDG) for therapy response evaluation of malignant lymphoma. Materials and methods: Nine patients with malignant lymphoma who underwent FDG-PET/MR before and after chemotherapy were included in this retrospective study. Average time between the two scans was 70 days. The scans were evaluated independently by two nuclear medicine physicians. The Ann Arbor classification was used to describe lymphoma stage. Furthermore, the readers also rated PET image quality using a five point scale. Weighted kappa was used to calculate interrater agreement. Results: The initial scan showed foci of increased FDG uptake in all patients, with Ann Arbor stage varying between I and IV. In the follow-up examination, all but one patient showed complete response to chemotherapy. PET image quality was rated as very good or excellent for all scans. Interrater agreement was excellent regarding Ann Arbor stage (kappa = 0.97) and good regarding image quality (kappa = 0.41). Conclusion PET/MR shows promising initial results for therapy response evaluation in lymphoma patients.

Ziel/Aim: Die Skelettszintigraphie mit F-18-NaF-PET weist eine hohe Sensitivität für die Detektion von Skelettmetastasen auf. Voraussetzung für deren Nachweis ist jedoch, dass die Metastase die Knochenmatrix alteriert. Knochenmarkmetastasen, die noch keine Stoffwechselreaktion der Knochenmatrix verursachen, entgehen dem Nachweis der Skelettszintigraphie. Im MRT können Knochenmarkmetastasen mit hoher Sensitivität detektiert werden. Ziel dieser Untersuchung ist es, den möglichen diagnostischen Zugewinn hinsichtlich der Detektion von Knochen- bzw. auch mgl. Knochenmarkmetastasen bei der kombinierten Anwendung der F-18-NaF-PET und einem GK-MRT mit einem Ganzkörper-PET/MR-Gerät zu untersuchen. Methodik/Methods: Seit Inbetriebnahme des PET/MR-Gerätes (Philips Ingenuity (TOF-PET/ 3T-MRT)) im Januar 2011 wurden 345 Untersuchungen durchgeführt, davon handelte es sich bei 96 Untersuchungen um Skelettszintigraphien mit F-18-Natriumfluorid mit der Frage nach Skelettmetastasen. Bei 52 Untersuchungen konnte neben dem Schwächungs-MRT und der PET noch ein diagnostisches Ganzkörper-MRT durchgeführt werden. 28 Patientendatensätze gehen in diese vorläufige Datenauswertung ein: 19 Männer, 9 Frauen, mittleres Alter 65 Jahre, 15 Prostata-Karzinome, 5 Mamma-Karzinome, 3 Schilddrüsen-Karzinome, 2 Karzinoide, 1 Bronchial-Karzinom, 1 CUP, 1 Plasmozytom. Injektion von 250 MBq F18-Natriumfluorid, Schwächungs-MRT; Start der Ganzkörper-PET ab 60 min p.i.. MRT: GK-coronar T1 und wenn möglich sagittale STIR der Wirbelsäule. Ergebnisse/Results: Qualitativ ergibt die NaF-PET Skelettszintigramme von hoher Qualität. Die coronaren GK-MRT und die sagittalen MRT-Schichten der Wirbelsäule ergänzen die PET mit exzellenten morphologischen Informationen. Metastasenverdächtige Läsionen wurden bei 16/28 Patienten gefunden. Davon bei 9 Patienten ausschließlich im NaF-PET, bei 5 Patienten fanden sich metastasenverdächtige Läsionen ausschließlich im MRT. Die MRT zeigte zusätzliche metastasenverdächtige Läsionen ü

Ziel/Aim: Ganzkörper-PET/MR-Geräte kombinieren die metabolische Information der Positronen-Emissions-Tomographie mit dem hohen Weichteilkontrast der Magnet-Resonanz-Tomographie in einem Untersuchungsablauf. Ziel dieser Untersuchung ist es, den möglichen diagnostischen Zugewinn bei der kombinierten Anwendung beider Untersuchungsmodalitäten beim Primärstaging von Patienten mit Kopf-Hals-Tumoren zu untersuchen Methodik/Methods: 40 Patienten (32 Männer, 8 Frauen, Alter 38 -82 Jahre, mittleres Alter 64 Jahre) mit histologisch gesicherten Kopf-Hals-Tumoren wurden an einem kombinierten PET/MR-Gerät (Philips Ingenuity PET-MR (TOF-PET/ 3T-MRT)) vor geplanter kurativer Operation untersucht (Untersuchungsablauf Kopf/Hals: Schwächungs-MRT; PET:350 MBq F-18-FDG, Start ab ca. 175 min p.i, 6 min /bed.; diagn. MRT: NV16-Spule, T1/T1-KM, T2, STIR). Beurteilt wurden die Detektierbarkeit des Primärtumors und von regionalen Lymphknotenmetastasen getrennt für PET, MRT und deren Kombination im Vergleich zur histologischen Aufarbeitung des Op-Präparates. Zum Ausschluss von Fernmetastasen wurde vor der dedizierten Kopf-Hals-Untersuchung eine konventionelle PET-Untersuchung des Körperstammes 60 min nach Injektion von 350 MBq F-18-FDG (ECAT-EXAT HR+, Siemens/CTI) durchgeführt. Ergebnisse/Results: Der Primärtumor war bei 5 Patienten im PET (bei geringer Größe), bei 10 Patienten im MRT (geringe Größe bzw. bei Metallartefakten) nicht abgrenzbar. Bei bisher 26 Patienten konnte ein Vergleich mit der Histologie bzgl. der LK-Metastasen erfolgen. Insgesamt wurden 863 LK histologisch beurteilt, davon waren 56 LK metastatisch befallen. Die Sensitivität und Spezifität hinsichtlich der Detektion von LK-Metastasen für PET und MRT betrug jeweils 69% bzw. 98%, die kombinierte Auswertung von PET-MRT erhöhte die Sensitivität auf 83%. Bei 8 Patienten wurde in der PET-Untersuchung des Körperstammes eine weitere hypernmetabole Läsion mit V.a. Zweittumor bzw. Fernmetastase detektiert. Schlussfolgerungen/Conclusi

Purpose/Introduction: Sequential PET/MR scanners for whole body investigations have been developed only recently and are starting to become commercially available. In 2011, one of the first of these combined systems (Ingenuity TF PET/MR, Philips) was installed at our institute. PET/MR is expected to offer new possibilities, in particular in the field of quantitative bimodal functional imaging [1]. Quantitative PET requires attenuation correction (AC) which is commonly based on a measurement of the photon attenuation using either a radioactive source in standalone PET (RSAC), or CT in PET/CT systems (CTAC). In PET/MR systems such a measurement cannot be performed, therefore AC is based on a dedicated MR measurement (MRAC) plus segmentation and tissue type identification [2]. Here, we report on a first evaluation of MRAC in whole body investigations with the new system. Subjects and Methods: Evaluation of MRAC is performed by a direct comparison of MRAC maps acquired with the Philips Ingenuity TF PET/MR and RSAC maps acquired with a Siemens ECAT Exact Hr+ PET scanner for 18 patients. Moreover, the quantitative influence of AC on the reconstructed images was investigated. Results: In most cases the MRAC maps match the RSAC maps very well. Artefacts due to dental implants and sternal cerclages were found. In one case, the algorithm was not able to separate tissue from air in the patients lung. The influence of these artefacts on the reconstructed PET image will be reported. Discussion/Conclusions: The vendor-provided MRAC algorithms yielded good results in our first patient measurements with respect to soft tissue and air segmentation. However, the algorithm relies on anatomic reference data and thus artefacts arise if the anatomy of the patient does not fit to the reference. In the future, an improved separation between tissue, bone and air without using anatomic reference data might be achieved with ultra short echo time sequences [3,4]. References: [1] Pichler, B.J.

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The recently introduced whole-body PET/MRI systems combine the unique metabolic imaging capabilities of positron emission tomography (PET) and the excellent soft tissue contrast of magnetic resonance imaging (MRI). The aim of this pilot study was to evaluate the feasibility of PET/MRI for initial staging of head and neck cancer. Materials and Methods:Ten male patients aged (age 52 to 78 years, median age 62.8 y) with histologically proven squamous cell carcinoma of the head and neck region were examined using both a stand-alone PET scanner and a wholebody PET/MRI scanner. Scanning started 60 minutes after intravenous administration of 350 MBq [18-F]-2-fluoro-2-deoxy-D-glucose (FDG) for the body trunk to exclude distant metastases. PET/MRI of the head and neck region followed immediately the first scan. The study was approved by the local ethics committee. A four-point-scale was used for qualitative evaluation of PET image quality. Furthermore, the signal-to-noise ratio (SNR) of the tumor and of both cerebellar hemispheres were determined for both PET data sets and used for semiquantitative comparison of image quality. Results were compared using the Wilcoxon matched-pair test.Results:The primary tumor was detected by PET/MRI in all 10 patients, by PET in 9 out of 10 cases, and by MRI in 9 out of 10 cases. Seven patients had lymph nodes suspect for metastatic disease. In two patients, lymph nodes considered suspect using MRI showed no pathological FDG uptake. In contrast, a single patient had lymph nodes considered suspect by PET but not by MRI. Visual evaluation of PET images showed consistent results (including regional contrast) for both scanners. There were no statistically significant differences regarding SNR between conventional PET and PET/MRI for the tumor and for both cerebellar hemispheres (p > 0.05). Conclusion: PET/MRI of head and neck cancer is feasible with a whole-body PET/MRI scanner with excellent image quality and - fusion. While previously availab

Combined PET/MR systems for whole body investigations have been developed recently and are now starting to become available. One of the first of these systems (Gemini TF PET/MR, Philips) has been installed at our site. PET/MR is expected to provide new possibilities, notably in the area of quantitative bimodal functional imaging. Quantitative PET imaging requires attenuation correction (AC), which is straightforward for PET/CT but not for PET/MR. In order to ensure quantitative accuracy of the PET data in the absence of a measured AC, one needs to use MR-based AC (MRAC), which relies on a combination of templates and accurate segmentation and tissue type identification of a suitable MR scan. Here, we report on a first evaluation of MRAC in phantoms as well as in patient investigations with the new system. Methodik/Methods: A NEMA IEC Body Phantom was used. Data were evaluated regarding quantitative accuracy of background and sphere activity as well as homogeneity of the background. Reconstructed resolution was assessed as well. Evaluation of MRAC in patients is performed by direct comparison of MRAC with a transmission based AC (TMAC) acquired with an ECAT Exact HR+ (Siemens). Ergebnisse/Results: Background inhomogeneity was found to be < 4% across the whole phantom. The reconstructed activity in the sphere inserts deviates from the known true values by < 5%. No artifacts related to erroneous AC could be observed in these measurements. The reconstructed resolution (FWHM) in these measurements was determined to be (5.01 - 5.48) mm. Patient studies will be performed in the coming months and evaluated as described above. The corresponding results will be reported. Schlussfolgerungen/Conclusions: The vendor provided MRAC algorithms yielded very good results in our first phantom measurements both with respect to quantitative accuracy as well as regarding general image quality. The upcoming patient investigations will show whether these findings can be confirmed in whole

This prospective study assessed the impact of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) on the staging an d possible consequential changes of treatment regimen in patients with Hodgkin´s lymphoma (HL). A total of 88 consecutive patients with histologically verified Hodgkin´s lymphoma underwent a PET scan in addition to conventional staging procedures. Treatment was based on the conventional staging only, and the results of the FDG-PET did not affect the treatment strategy. The evaluation focused on the suggested change in clinical stage according to the Ann Arbor classification and on the suggested change in treatment strategy rather than on a lesion-by-lesion analysis. Using all the methods performed as the standard of reference, 18F-FDG-PET staging was concordant with conventional staging in 70 out of 88 patients (80 %). 18F-fluorodeoxyglucose positron emission tomography suggested a change to a different clinical stage in 18 patients (20 %). Management would have been changed in 16 patients (18 %): intensification of treatment in nine patients (10 %) and minimisation of treatment in seven patients (8 %). In the 44 patients with early disease (stage IA - IIB), treatment would have benn intensified in nine out of 44 patients (20 %). 18F-fluorodeoxyglucose postitron emission tomography is a relevant noninvasive method that supplements conventional staging procedures and should therefore be used routinely to stage Hodgkin´s lymphoma, particularly in patients with an early stage.

Susceptibilitys contrast based MR perfusion measurement in contrast uptaking tissues are complicated by the contribution of the interstitially deposited contrast medium (CM) to the shortening of both T1 and T2. Applying double echo sequences, both contributions can be corrected for. In this paper, the consequences of different degrees of correction on perfusion parameters are investigated.

Rationale and Objectives. In this phase III study, we evaluated the efficacy and safety of a negative contrast medium, ferristene (oral magnetic particles), among 277 patients undergoing magnetic resonance (MR) imaging of the abdomen. Methods. Enhanced (800 ml ferristene) MR images were compared with unenhanced MR images in an intraindividual-patient control design. Adverse events were recorded. The examinations were performed on 1.5-T MR systems (T1- and T2-weighted sequences). Results. Ferristene increased the diagnostic information in 50.9% of the patients, particularly in those with abdominal masses, lymphoma, or pancreatic disease. Distribution of ferristene in the stomach, duodenum, jejunum, and ileum was complete or sufficient in 70.5-85% of the studies. In 64% of the patients, we were confident in the MR findings after the use of ferristene, and ferristene disclosed additional findings in 22% of the patients. The incidence of adverse events was 9.0%, but only 3.6% of all patients experienced ferristene-related adverse events (e.g., nausea, vomiting). Most events were mild or moderate in intensity. Conclusion. Ferristene was well tolerated, and for 50% of the patients it added useful diagnostic information.