MR-Based PET Attenuation Correction for PET/MR Imaging

Bezrukov, Ilja; Mantlik, Frederic; Schmidt, Holger; Schoelkopf, Bernhard; Pichler, Bernd J.

doi:10.1053/j.semnuclmed.2012.08.002

Cited by 140 publications

(128 citation statements)

References 39 publications

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“…Despite the possible benefits, surprisingly little has been done in this particular area although interest appears to be increasing as combined PET/MRI machines make their way into clinical practice [2]. In contrast, great effort has been devoted to skull stripping, the process of segmenting brain from nonbrain tissue without further considering the composition of the non-brain tissue [3], as well as the subsequent segmentation of the brain into different types of soft tissue [4].…”

Section: Introductionmentioning

confidence: 99%

Skull Segmentation in MRI by a Support Vector Machine Combining Local and Global Features

Sjölund

Järlideni

Andersson

et al. 2014

2014 22nd International Conference on Pattern Recognition

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Abstract-Magnetic resonance (MR) images lack information about radiation transport-a fact which is problematic in applications such as radiotherapy planning and attenuation correction in combined PET/MR imaging. To remedy this, a crude but common approach is to approximate all tissue properties as equivalent to those of water. We improve upon this using an algorithm that automatically identifies bone tissue in MR. More specifically; we focus on segmenting the skull prior to stereotactic neurosurgery, where it is common that only MR images are available.In the proposed approach, a machine learning algorithm known as a support vector machine is trained on patients for which both a CT and an MR scan are available. As input, a combination of local and global information is used. The latter is needed to distinguish between bone and air as this is not possible based only on the local image intensity.A whole skull segmentation is achievable in minutes. In a comparison with two other methods, one based on mathematical morphology and the other on deformable registration, the proposed method was found to yield consistently better segmentations.

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Section: Introductionmentioning

confidence: 99%

Skull Segmentation in MRI by a Support Vector Machine Combining Local and Global Features

Sjölund

Järlideni

Andersson

et al. 2014

2014 22nd International Conference on Pattern Recognition

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“…The first application is in combined PET/MR imaging-currently transitioning to reach its full clinical potential-where attenuation correction is necessary but CT acquisition would require an additional scan (Bezrukov, Mantlik, Schmidt, Schölkopf & Pichler 2013). The second application is in certain types of radiotherapy planning, where CT's limited soft tissue contrast stunts accurate tumor delineation whereas MR provides valuable guidance.…”

Section: Introductionmentioning

confidence: 99%

Generating patient specific pseudo-CT of the head from MR using atlas-based regression

et al. 2015

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Abstract. Radiotherapy planning and attenuation correction of PET images require simulation of radiation transport. The necessary physical properties are typically derived from computed tomography (CT) images, but in some cases, including stereotactic neurosurgery and combined PET/MR imaging, only magnetic resonance (MR) images are available. With these applications in mind, we describe how a realistic, patient-specific, pseudo-CT of the head can be derived from anatomical MR images. We refer to the method as atlas-based regression, because of its similarity to atlas-based segmentation.Given a target MR and an atlas database comprising MR and CT pairs, atlas-based regression works by registering each atlas MR to the target MR, applying the resulting displacement fields to the corresponding atlas CTs and, finally, fusing the deformed atlas CTs into a single pseudo-CT.We use a deformable registration algorithm known as the Morphon and augment it with a certainty mask that allows a tailoring of the influence certain regions are allowed to have on the registration. Moreover, we propose a novel method of fusion, wherein the collection of deformed CTs is iteratively registered to their joint mean, and find that the resulting mean CT becomes more similar to the target CT. However, the voxelwise median provided even better results; at least as good as earlier work that required special MR imaging techniques. This makes atlas-based regression a good candidate for clinical use.

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“…In general, resulting PET quantification is accurate for adult and pediatric patients. However, significant quantitative errors are observed in and around skeletal structures (e. g., bone metastases and bone marrow) as bone attenuation is routinely neglected [7,15,18]. Furthermore, typical segmentation artifacts can occur in MR-based attenuation correction that are mostly observed around metal implants causing MR susceptibility artifacts.…”

Section: Image Interpretation and Pitfallsmentioning

confidence: 99%

“…cients are not measured but usually derived based on tissue segmentation using T1-weighted sequences [15]. In general, resulting PET quantification is accurate for adult and pediatric patients.…”

Section: Image Interpretation and Pitfallsmentioning

confidence: 99%

“…In addition, a dedicated MR sequence has to be acquired for each bed position for MR-based attenuation correction. On most scanners, a double-echo chemical shift gradient-echo sequence is used for this purpose (Dixon technique) [15]. After this basic module, additional MRI sequences are usually measured depending on the clinical question, available previous imaging, and patient compliance ( • " Fig.…”

Section: Examination Protocolmentioning

confidence: 99%

See 1 more Smart Citation

Pediatric Oncologic Imaging: A Key Application of Combined PET/MRI

Gatidis¹,

Fougère²,

Schaefer³

2016

Fortschr Röntgenstr

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Pediatric imaging has been identified as a key application of combined whole-body PET/MRI. First studies have revealed the clinical feasibility and possible advantages of PET/MRI over PET/CT and MRI. Besides a significant reduction in radiation exposure of about 50???75?%, combined whole-body PET/MRI offers the diagnostic advantage of the multiparametric characterization of pathophysiologic processes and helps reduce the number of necessary imaging studies. However, very few studies focusing on pediatric PET/MRI have been published to date. Additional studies are necessary in order to fully appreciate the clinical impact of this novel method. This review article shall summarize the existing literature concerning pediatric PET/MRI and give insight into the practical experience derived from over 160 pediatric PET/MRI examinations that were performed in T?bingen. Key Points: ??Combined PET/MR is a promising imaging modality in pediatric oncology. ??Using combined PET/MRI, diagnostic radiation exposure of pediatric patients and the number of necessary imaging studies can be reduced. ??Further clinical studies are necessary in order to define specific indications for combined PET/MRI in pediatric radiology. Citation Format: ??Gatidis S, la Foug?re C, Schaefer J F Pediatric Oncologic Imaging: A Key Application of Combined PET/MRI. Fortschr R?ntgenstr 2016; 188: 359???364

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MR-Based PET Attenuation Correction for PET/MR Imaging

Cited by 140 publications

References 39 publications

Skull Segmentation in MRI by a Support Vector Machine Combining Local and Global Features

Skull Segmentation in MRI by a Support Vector Machine Combining Local and Global Features

Generating patient specific pseudo-CT of the head from MR using atlas-based regression

Pediatric Oncologic Imaging: A Key Application of Combined PET/MRI

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