UNLABELLED: Simultaneous PET and MRI using new hybrid PET/MRI systems promises optimal spatial and temporal coregistration of structural, functional, and molecular image data. In a pilot study of 10 patients with intracranial masses, the feasibility of tumor assessment using a PET/MRI system comprising lutetium oxyorthosilicate scintillators coupled to avalanche photodiodes was evaluated, and quantification accuracy was compared with conventional PET/CT datasets. METHODS: All measurements were performed with a hybrid PET/MRI scanner consisting of a conventional 3-T MRI scanner in combination with an inserted MRI-compatible PET system. Attenuation correction of PET/MR images was computed from MRI datasets. Diagnoses at the time of referral were low-grade astrocytoma (n = 2), suspicion of low-grade astrocytoma (n = 1), anaplastic astrocytoma (World Health Organization grade III; n = 1), glioblastoma (n = 2), atypical neurocytoma (n = 1), and meningioma (n = 3). In the glial tumors, (11)C-methionine was used for PET; in the meningiomas, (68)Ga-DOTATOC was administered. Tumor-to-gray matter and tumor-to-white matter ratios were calculated for gliomas, and tracer uptake of meningiomas was referenced to nasal mucosa. PET/MRI was performed directly after clinically indicated PET/CT examination. RESULTS: In all patients, the PET datasets showed similar diagnostic image quality on the hybrid PET/MRI and the PET/CT studies; however, slight streak artifacts were visible in coronal and sagittal sections when using the higher intrinsic resolution of the PET/MRI insert. Prefiltering of images with a 4-mm gaussian filter at a resolution comparable to that of the PET/CT system virtually eliminated these artifacts. Although acquisition of the PET/MR images started at 30-60 min after PET/CT (20.4-min half-life of (11)C) acquisition, the signal-to-noise ratio was good enough, thus underlining the high sensitivity of the PET insert, compared with whole-body PET systems. The computed tumor-to-reference tissue ratios exhibited an excellent accordance between the PET/MRI and PET/CT systems, with a Pearson correlation coefficient of 0.98. Mean paired relative error was 7.9% +/- 12.2%. No significant artifacts or distortions were detected in the simultaneously acquired MR images using the PET/MRI scanner. CONCLUSION: Structural, functional, and molecular imaging in patients with brain tumors is feasible with diagnostic imaging quality using simultaneous hybrid PET/MR image acquisition.
UNLABELLED: Simultaneous PET and MRI using new hybrid PET/MRI systems promises optimal spatial and temporal coregistration of structural, functional, and molecular image data. In a pilot study of 10 patients with intracranial masses, the feasibility of tumor assessment using a PET/MRI system comprising lutetium oxyorthosilicate scintillators coupled to avalanche photodiodes was evaluated, and quantification accuracy was compared with conventional PET/CT datasets. METHODS: All measurements were performed with a hybrid PET/MRI scanner consisting of a conventional 3-T MRI scanner in combination with an inserted MRI-compatible PET system. Attenuation correction of PET/MR images was computed from MRI datasets. Diagnoses at the time of referral were low-grade astrocytoma (n = 2), suspicion of low-grade astrocytoma (n = 1), anaplastic astrocytoma (World Health Organization grade III; n = 1), glioblastoma (n = 2), atypical neurocytoma (n = 1), and meningioma (n = 3). In the glial tumors, (11)C-methionine was used for PET; in the meningiomas, (68)Ga-DOTATOC was administered. Tumor-to-gray matter and tumor-to-white matter ratios were calculated for gliomas, and tracer uptake of meningiomas was referenced to nasal mucosa. PET/MRI was performed directly after clinically indicated PET/CT examination. RESULTS: In all patients, the PET datasets showed similar diagnostic image quality on the hybrid PET/MRI and the PET/CT studies; however, slight streak artifacts were visible in coronal and sagittal sections when using the higher intrinsic resolution of the PET/MRI insert. Prefiltering of images with a 4-mm gaussian filter at a resolution comparable to that of the PET/CT system virtually eliminated these artifacts. Although acquisition of the PET/MR images started at 30-60 min after PET/CT (20.4-min half-life of (11)C) acquisition, the signal-to-noise ratio was good enough, thus underlining the high sensitivity of the PET insert, compared with whole-body PET systems. The computed tumor-to-reference tissue ratios exhibited an excellent accordance between the PET/MRI and PET/CT systems, with a Pearson correlation coefficient of 0.98. Mean paired relative error was 7.9% +/- 12.2%. No significant artifacts or distortions were detected in the simultaneously acquired MR images using the PET/MRI scanner. CONCLUSION: Structural, functional, and molecular imaging in patients with brain tumors is feasible with diagnostic imaging quality using simultaneous hybrid PET/MR image acquisition.
Authors: Sasan Partovi; Andres Kohan; Christian Rubbert; Jose Luis Vercher-Conejero; Chiara Gaeta; Roger Yuh; Lisa Zipp; Karin A Herrmann; Mark R Robbin; Zhenghong Lee; Raymond F Muzic; Peter Faulhaber; Pablo R Ros Journal: Am J Nucl Med Mol Imaging Date: 2014-03-20
Authors: Svetlana Balyasnikova; Johan Löfgren; Robin de Nijs; Yanna Zamogilnaya; Liselotte Højgaard; Barbara M Fischer Journal: Am J Nucl Med Mol Imaging Date: 2012-10-15
Authors: Marco Wiesmüller; Harald H Quick; Bharath Navalpakkam; Michael M Lell; Michael Uder; Philipp Ritt; Daniela Schmidt; Michael Beck; Torsten Kuwert; Carl C von Gall Journal: Eur J Nucl Med Mol Imaging Date: 2012-10-06 Impact factor: 9.236
Authors: Lingzhi Hu; Kuan-Hao Su; Gisele C Pereira; Anu Grover; Bryan Traughber; Melanie Traughber; Raymond F Muzic Journal: Med Phys Date: 2014-10 Impact factor: 4.071