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![MELAS syndrome. Single-voxel proton MR spectroscopy over the centrum semiovale in a patient with MELAS syndrome shows normal Cho (1), Cr (2), and NAA (3) and mild elevation of lactate (4) (from Castillo et al [39]).](publication/10876640/figure/fig8/AS:667824951414785@1536233284159/MELAS-syndrome-Single-voxel-proton-MR-spectroscopy-over-the-centrum-semiovale-in-a.png)
MELAS syndrome. Single-voxel proton MR spectroscopy over the centrum semiovale in a patient with MELAS syndrome shows normal Cho (1), Cr (2), and NAA (3) and mild elevation of lactate (4) (from Castillo et al [39]).
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Proton magnetic resonance spectroscopy (H1-MRS) has been increasingly receiving more attention from radiologists, neurosurgeons, radiation and medical oncologists in the "in situ" clinical evaluation of human tumors. The utilization of H1-MRS, especially in human brain tumors, coupled to both routine magnetic resonance imaging (MRI) and functional...
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The next major development is expected to be photon-counting computed tomography (CT), a novel method that has the potential to transform clinical CT. An enormous amount of research has been done recently to show the advancements in hardware assembly and its operating principles. The Medline database search was used to find the papers for this revi...
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... In the clinical setting, in vivo brain MRS has shown tremendous capabilities in oncology [10][11][12][13][14][15][16] and has provided notable contributions in the fields of neuropsychiatry [17] and neurology [18], among others. ...
In vivo proton magnetic resonance spectroscopy
(MRS) has been around for nearly thirty (30) years and has
proven itself to be an indispensable tool at the hands of an
experienced practitioner. However, in certain occasions such as
when there are hemorrhagic foci inside the volume of interest,
the spectral resolution is hindered, due to paramagnetic effects.
In these cases, spectra acquired with automatic shimming of the
static magnetic field B0 field may present broad linewidths and
overall poor spectral quality. In such a scenario, the MRS
practitioner must perform a manual shim, by appropriately
adjusting the strengths of the gradient coils. The purpose of this
study was to provide a step-by-step guide for manually
shimming the B0, to improve spectral resolution of acquired
spectra and, thus, to potentially increase the diagnostic power
of the method. Furthermore, the effect of spectral resolution on
the signal-to-noise ratio (SNR) of metabolite peaks was also
investigated in a phantom study at two field strengths, where all
acquisition parameters and conditions were identical, with the
exception of the spectral linewidth which ranged from 1 Hz to 8
Hz (at 1.5T), or equivalently from 2 Hz to 16 Hz (at 3.0T).
... The association of choline, whose value increases as a result of the increase in cellular membrane synthesis, and a decrease due to neuron loss, is the distinguishing feature of actively growing malignant brain neoplasms (15). As the malignancy of gliomas increases, NAA and creatinine levels decrease, while choline, lipid and lactate peaks increase. ...
OBJECTIVE: Preoperative diagnosis is very important in determining the treatment algorithm in cranial lesions. The aim of this study is to compare the results of magnetic resonance spectroscopy, which is one of the preoperative imaging methods, with the results of pathology and to reveal its effectiveness in diagnosis.MATERIAL AND METHODS: Thirty five patients who underwent preoperative magnetic resonance spectroscopy imaging among 75 patients who were operated for cranial lesions in our clinic between 2016 - 2019 were included in the study. N-acetyl aspartate, creatine, choline and lactate values were calculated as biochemical metabolites, and preoperative diagnoses made according to these values were compared with postoperative pathology results and discussed in the light of the literature.RESULTS: A total of 35 patients, 20 male and 15 female, were included in the study. The age range of the patients was between 18 - 82. As a result of magnetic resonance spectroscopy, 29 patients were diagnosed with high grade glial tumors. As a result of the postoperative evaluation, the magnetic resonance spectroscopy results of 27 patients were found to be compatible with the pathology results, while differences were observed in 8 patients. A significant increase in choline peak and choline / NAA ratio was noted in high-grade glial tumors.CONCLUSIONS: There is a high correlation between the preoperative evaluations obtained by magnetic resonance spectroscopy which is used in the differential diagnosis of cranial lesions, and the pathological diagnosis.
... Since the 1990s, studies on patients with brain lesions and primary brain tumours have shown that MRS can distinguish between different grades of malignancy and even intratumoral heterogeneity [30]. As mentioned before, peaks or absences from certain metabolites can discriminate between different brain lesions [26,[32][33][34]40]. ...
... The resulting MR spectrum comprises resonances or peaks from different metabolites expressed in parts per million, or ppm, a radiofrequency scale. The metabolites in the 1-5 ppm range are the ones analysed in the clinical setting (in-vivo 1 H MRS)[26,[29][30][31] . ...
Proton magnetic resonance spectroscopy (1H-MRS) delivers information about the non-invasive metabolic landscape of brain pathologies. 1H-MRS is used in clinical setting in addition to MRI for diagnostic, prognostic and treatment response assessments, but the use of this radiological tool is not entirely widespread. The importance of developing automated analysis tools for 1H-MRS lies in the possibility of a straightforward application and simplified interpretation of metabolic and genetic data that allow for incorporation into the daily practice of a broad audi-ence. Here, we report a prospective clinical imaging trial (DRKS00019855) which aimed to de-velop a novel MR-spectroscopy-based algorithm for in-depth characterization of brain lesions and prediction of molecular traits. Dimensional reduction of metabolic profiles demonstrated distinct patterns throughout pathologies. We combined a deep autoencoder and multi-layer linear discriminant models for voxel-wise prediction of the molecular profile based on MRS imaging. Molecular subtypes were predicted by an overall accuracy of 91.2% using a classifier score. Our study indicates a first step into combining the metabolic and molecular traits of lesions for ad-vancing the preoperative diagnostic workup of brain tumors and improve personalized tumor treatment.
... By recognizing characteristic changes in the metabolite pro le within a brain lesion, as compared to the normal brain parenchyma, MRS provides important diagnostic biochemical information that is not obtainable through conventional anatomic MRI [30]. The technique has been evaluated for the di erentiation of neoplastic from non-neoplastic CNS lesions (such as brain abscess, demyelination, infarct, and radiation necrosis) with good results. ...
Cerebral gliomas comprise a heterogeneous group of primary neoplasms of the central nervous system, representing a signifcant cause of cancer morbidity and mortality. Contrast-enhanced magnetic resonance imaging (MRI) is paramount for identifying structural brain abnormalities related to the development of gliomas. Although morphological MRI remains the current standard of care for initial diagnostic workup, surgical planning, monitoring therapy response and surveillance during follow-up, it is rather diffcult to define tumor grade and boundaries and to assess response to radiochemotherapy solely by contrast-enhancement, due to a variety of factors influencing blood-brain barrier (BBB) permeability and contrast agent distribution. The nature of a lesion lies beyond often misleading gross structural patterns, down to the cellular and molecular level, hence the imaging techniques of advanced multimodal MRI and
positron emission tomography (PET) have emerged to provide critical non-invasive insight into the underlying
biology of primary brain cancer. Out of the various PET radiotracers, labeled amino acids are of particular significance due to their non-dependency on BBB disruption to reach glioma cells and their excellent tumor-to-background contrast. After discussing the basic imaging principles of MR perfusion, diffusion, spectroscopy and PET in glioma, this review focuses on the correlative imaging with amino acid
PET and advanced MRI techniques in tumor grading and staging, in guiding stereotactic biopsy and surgical
excision and in assessing therapy response, post-therapy surveillance and prognosis. Lastly, a reference
is made on the expanding availability of integrated PET/MRI systems and the resulting benefits of simultaneous
image acquisition.
... Increased lactate suggests tumor hypoxia and lipid indicates necrosis as is seen in HGG histopathology. 32 MRS is technically challenging to acquire in clinical practice with overlap seen between tumors and tumor mimickers. ...
PET/MR imaging benefits neurologic clinical care and research by providing spatially and temporally matched anatomic MR imaging, advanced MR physiologic imaging, and metabolic PET imaging. MR imaging sequences and PET tracers can be modified to target physiology specific to a neurologic disease process, with applications in neurooncology, epilepsy, dementia, cerebrovascular disease, and psychiatric and neurologic research. Simultaneous PET/MR imaging provides efficient acquisition of multiple temporally matched datasets, and opportunities for motion correction and improved anatomic assignment of PET data. Current challenges include optimizing MR imaging-based attenuation correction and necessity for dual expertise in PET and MR imaging.
... The metabolites that can be investigated via MRS methods include but are not limited to N-acetylaspartate (NAA), choline (Cho), creatine (Cr), lactate, glutamate (Glu), glutamine (Gln) and lipids. Different metabolites are involved in different physiological and pathological procedures, so can be utilized to characterize the metabolism associated with different diseases including cancer (88). MRS has been preliminarily explored for HNC in recent years ( Figure 5) (89)(90)(91)(92)(93). ...
Radiation therapy (RT), in particular intensity-modulated radiation therapy (IMRT), is becoming a more important nonsurgical treatment strategy in head and neck cancer (HNC). The further development of IMRT imposes more critical requirements on clinical imaging, and these requirements cannot be fully fulfilled by the existing radiotherapeutic imaging workhorse of X-ray based imaging methods. Magnetic resonance imaging (MRI) has increasingly gained more interests from radiation oncology community and holds great potential for RT applications, mainly due to its non-ionizing radiation nature and superior soft tissue image contrast. Beyond anatomical imaging, MRI provides a variety of functional imaging techniques to investigate the functionality and metabolism of living tissue. The major purpose of this paper is to give a concise and timely review of some advanced functional MRI techniques that may potentially benefit conformal, tailored and adaptive RT in the HNC. The basic principle of each functional MRI technique is briefly introduced and their use in RT of HNC is described. Limitation and future development of these functional MRI techniques for HNC radiotherapeutic applications are discussed. More rigorous studies are warranted to translate the hypotheses into credible evidences in order to establish the role of functional MRI in the clinical practice of head and neck radiation oncology.
... This technique is already used for the diagnosis and follow up of brain, prostate and breast tumors. 1H-MRS, indeed, allows to measure the concentration of the main metabolites of living organs, providing biochemical variations within the tissues [17][18][19]. ...
... Also lactates and lipids concentrations were altered but with less significance: the former increased probably for the hypossic environment, the latters reduced for alterations of the cells membranes. 1 H-MRS is already used in clinical oncology for the diagnosis and follow-up of prostate, breast and brain tumors [17,19,27]. Indeed, choline is the essential part of the phospholipids which compose the cell membrane and its increasement can reflect a higher turn-over as membrane disruption or cell proliferation (e.g., in tumours) [17,28]. ...
... This technique is already used for the diagnosis and follow up of brain, prostate and breast tumors. 1H-MRS, indeed, allows to measure the concentration of the main metabolites of living organs, providing biochemical variations within the tissues [17][18][19]. ...
... Also lactates and lipids concentrations were altered but with less significance: the former increased probably for the hypossic environment, the latters reduced for alterations of the cells membranes. 1 H-MRS is already used in clinical oncology for the diagnosis and follow-up of prostate, breast and brain tumors [17,19,27]. Indeed, choline is the essential part of the phospholipids which compose the cell membrane and its increasement can reflect a higher turn-over as membrane disruption or cell proliferation (e.g., in tumours) [17,28]. ...
... Each of these metabolites yields a characteristic resonance frequency across a spectrum determined by the atomic nucleus of interest. Proton MR spectroscopy ( 1 H-MRS) depicts changes in the metabolite profile of certain brain tumors as compared with normal brain tissue (5). Key metabolites of interest include N-acetylaspartate, for neuronal integrity; choline, for cellular membrane turnover; creatine, for bioenergy stores; lactate, for anaerobic glycolysis; lipids, byproducts of necrosis; glutamate-glutamine and g-aminobutyric acid, neurotransmitters; and myoinositol, a glial cell marker (6). ...
Standard magnetic resonance imaging (MRI) and computed tomography are routinely employed for anatomic diagnosis in brain tumors. Pre-therapy planning and post-treatment response assessments rely heavily on gadolinium-enhanced MRI. Advanced MRI techniques and positron emission tomography (PET) imaging offer physiologic, metabolic or functional information about tumor biology that goes beyond the diagnostic yield of standard anatomic imaging. With the advent of combined PET-MRI scanners, we are entering an era wherein the relationships among different elements of tumor metabolism can be simultaneously explored through multi-modality MRI and PET imaging. The purpose of this review is to provide a practical and clinically-relevant overview of current anatomic and physiologic imaging of brain tumors as a foundation for further investigations, with a primary focus on MRI and PET techniques that have demonstrated utility in the current care of brain tumor patients.
Copyright © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
... Importantly, PET-CT and MRS/MRSI are complementary in their advantages that are whole body scans and localized diagnostics for the former and latter, respectively. Overall, MRS/MRSI are viewed by leading experts as a modality which could revolutionize not only cancer diagnostics, but also molecular-image guided surgery and biopsy, as well as target delineation for radiotherapy (6)(7)(8)(9)(10)(11)(12)(13)(14). However, robust and more reliable signal processing within MRS/ MRSI than that in the past and current practice is crucial for achieving this potential, as emphasized by e.g. the U.S. National Cancer Institute (6). ...
... Refs. (8,11,12,37,38). Viewed in that light, the limitations of the FFT become all the more striking. ...
With the rapidly-expanding sophistication in our understanding of cancer cell biology, molecular imaging offers a critical bridge to oncology. Molecular imaging through magnetic resonance spectroscopy (MRS) can provide information about many metabolites at the same time. Since MRS entails no ionizing radiation, repeated monitoring, including screening can be performed. However, MRS via the fast Fourier transform (FFT) has poor resolution and signal-to-noise ratio (SNR). Moreover, subjective and non-unique (ambiguous) fittings of FFT spectra cannot provide reliable quantification of clinical usefulness. In sharp contrast, objective and unique (unambiguous) signal processing by the fast Pade transform (FPT) can increase resolution and retrieve the true quantitative metabolic information. To illustrate, we apply the FPT to in vitro MRS data as encoded from malignant ovarian cyst fluid and perform detailed analysis. This problem area is particularly in need of timely diagnostics by more advanced modalities, such as high-resolution MRS, since conventional methods usually detect ovarian cancers at late stages with poor prognosis, whereas at an early stage the prognosis is excellent. The reliability and robustness of the FPT is assessed for time signals contaminated with varying noise levels. In the presence of higher background noise, all physical metabolites were unequivocally identified and their concentrations precisely extracted, using small fractions of the total signal length. Via the "signal-noise separation" concept alongside the "stability test", all non-physical information was binned, such that fully denoised spectra were generated. These results imply that a reformulation of data acquisition is needed, as guided by the FPT in MRS, since a small number of short transient time signals can provide high resolution and good SNR. This would enhance the diagnostic accuracy of MRS and shorten examination times, thereby improving efficiency and cost-effectiveness of this high throughput cancer diagnostic modality. Such advantages could be particularly important for more effective ovarian cancer detection, as well as more broadly for improved diagnostics and treatment within oncology.
