Volume Selection Strategies for In Vivo Biological Spectroscopy

Ordidge, Roger J.; Connelly, Alan; Gordon, R. E.; Lohman, Joost A. B.

doi:10.1007/978-1-4684-8178-5_9

Cited by 51 publications

(67 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…13) by applying selective radiofrequency excitation pulses such as stimulated echo acquisition mode (86) or point-resolved spectroscopy (87,88). The Fourier transformation of the acquired signal provides a defined spectrum that allows for discrimination between various metabolites.…”

Section: Beyond Anatomic Mri-toward Functional Imagingmentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

View full text Add to dashboard Cite

This review concentrates on the latest advances in molecular imaging technology, including PET, MRI, and optical imaging. In PET, significant improvements in tumor detection and image resolution have been achieved by introducing new scintillation materials, iterative image reconstruction, and correction methods. These advances enabled the first clinical scanners capable of time-of-flight detection and incorporating point-spread-function reconstruction to compensate for depth-of-interaction effects. In the field of MRI, the most important developments in recent years have mainly been MRI systems with higher field strengths and improved radiofrequency coil technology. Hyperpolarized imaging, functional MRI, and MR spectroscopy provide molecular information in vivo. A special focus of this review article is multimodality imaging and, in particular, the emerging field of combined PET/MRI. PETi s a high-performance imaging technology that can image the whole-body distribution of positron-emitting biomarkers with high sensitivity. The invention of PET dates back more than 30 y. However, the acceptance of PET as a routine clinical diagnostic tool has been hampered by the need for an on-site cyclotron and a radiochemistry unit for the production of the short-lived radiotracers (1-7). With the availability of commercial radiopharmacies that supply PET probes and with the relatively broad insurance coverage for a variety of clinical indications, the number of PET centers now totals more than 2,000 worldwide.Major technologic milestones in the development of PET include the discovery of faster and brighter scintillators such as lutetium oxyorthosilicate (LSO), gadolinium oxyorthosilicate, and lutetium yttrium oxyorthosilicate. Furthermore, the continuing development of the detectors, progressing from one-to-one scintillator-to-photomultiplier-tube (PMT) coupling (8,9) to advanced block and Anger readout schemes, helps to limit the costs of a PET scanner by providing a multiplexed readout and reduced electronic channels (10-13).The use of faster scintillators enabled the transition from 2-dimensional data acquisitions for whole-body PET, using lead or tungsten collimators as septa (14-16), to 3-dimensional (3D) acquisitions (17). However, approximately an 8-fold increase in detection sensitivity is accompanied by an increased fraction of random and scattered photon events leading to degradation of image quality if not corrected during image reconstruction (18). This degradation effectively reduces the increase in sensitivity from a factor of 8 to approximately 5-fold. To achieve high-quality and quantitative PET data, various image reconstruction techniques have evolved (19). One simple approach is filtered backprojection, which is computationally fast but results in poor image quality if the count statistics of the available PET data are inadequate. Better image quality and improved spatial resolution are achieved by iterative methods such as ordered-subset expectation maximization or maximumlikelihood expectation maximiza...

show abstract

Section: Beyond Anatomic Mri-toward Functional Imagingmentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

View full text Add to dashboard Cite

show abstract

“…The voxel size was either 1.8 × 1.8 × 1.8 cm 3 or 2.0 × 2.0 × 2.0 cm 3 . Localization was obtained using the point-resolved spin-echo sequence (PRESS) (13,14) followed by voxel shimming. The typical water peak linewidth (FWHM) ranged from 8 to 17 Hz.…”

Section: Mri/mrs Protocolmentioning

confidence: 99%

Quantitative correlation between 1H MRS and dynamic contrast-enhanced MRI of human breast cancer

Baek

Chen

et al. 2008

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Proton MR spectroscopy ( 1 H MRS) and dynamic contrast-enhanced (DCE) MR imaging provide functional information, including vascular volume, vascular permeability, and choline (Cho) metabolism. In this study, we applied these two imaging modalities to quantitatively characterize 36 malignant breast lesions in 32 patients and analyzed the correlation between them. The Cho concentration was quantified by single-voxel 1 H MRS using water as an internal reference. The measured Cho levels ranged from 0.32 to 10.47 mmol/kg, consistent with previously reported values. In 25 mass type lesions, the Cho concentration was significantly correlated with tumor size (r = 0.69, p < 0.0002). In addition, the Cho level was found to be significantly higher in lesions presenting as mass type lesions compared to non-mass type diffuse enhancements (p = 0.035). The enhancement kinetics from tissues covered within each MRS voxel were measured and analyzed with a 2-compartmental model to obtain pharmacokinetic parameters K trans and k ep . A significant correlation was found between the Cho level and pharmacokinetic parameter k ep (r = 0.62, p < 0.0001), indicating that tissues with a high Cho level have higher wash-out rates in DCE MR imaging. The results suggest a correlation between choline metabolism and angiogenesis activity, which might be explained by the association of Cho with cell replication and angiogenesis required to support tumor growth.

show abstract

“…A double spin-echo point-resolved spectroscopy sequence was used for VOI localization. 13,14 Each measurement was performed with a TR of 2000 ms, a TE of 144 ms, 2048 time domain data points, 4000-Hz spectral width, and 128 signals acquired. After zero filling to 4096 data points, gaussian multiplication of 5 Hz, exponential multiplication of Ϫ4 Hz (line broadening), Fourier transformation, and linear baseline correction, N-acetylaspartate (NAA; referenced at 2.0 ppm), total choline, total creatine, and lactate peaks were identified by their chemical shifts.…”

Section: Mri Methodsmentioning

confidence: 99%

Hemodynamic and Metabolic Changes in Transient Ischemic Attack Patients

Bisschops

Kappelle

Mali

2002

Stroke

View full text Add to dashboard Cite

Background and Purpose-We investigated whether patients with transient ischemic attack (TIA) have systemic low flow to the brain or an abnormal intracranial flow distribution caused by an abnormal anatomy of the circle of Willis. Furthermore, we investigated whether metabolic changes were present in the brain. Methods-Forty-four patients with clinically diagnosed TIA were prospectively included in our study. Clinical and neurological data were compiled. MR imaging; quantitative flow measurements of the internal carotid, middle cerebral, and basilar arteries; MR angiography of the circle of Willis; and 1 H-MR spectroscopy were performed in all patients within 3 days of onset of symptoms. Results-Compared with control subjects, TIA patients did not have altered flow volume in any of the arteries and had normal flow distribution through the circle of Willis. In TIA patients, the N-acetylaspartate (NAA)/choline ratio in noninfarcted regions was significantly decreased in the symptomatic hemisphere (

show abstract

Volume Selection Strategies for In Vivo Biological Spectroscopy

Cited by 51 publications

References 14 publications

Latest Advances in Molecular Imaging Instrumentation

Latest Advances in Molecular Imaging Instrumentation

Quantitative correlation between 1H MRS and dynamic contrast-enhanced MRI of human breast cancer

Hemodynamic and Metabolic Changes in Transient Ischemic Attack Patients

Contact Info

Product

Resources

About