Three-dimensional Magnetic Resonance Spectroscopy Research Articles

The Role of Three-Dimensional Magnetic Resonance Spectroscopy in Diagnosing and Grading of Gliomas

In patients with suspected cerebral glioma, non-invasive preoperative evaluation of brain tumor grading is important for planning treatment and prognostication. Conventional MRI is an established and useful tool in brain tumor grading, but MRI-based tumor grading may lead to low-grade or high-grade misclassification in some cases. Three-dimensional magnetic resonance spectroscopy (MRS) has been proposed as an alternative modality for grading cerebral glioma.

Prediction of prostate cancer recurrence after radiation therapy using multiparametric magnetic resonance imaging and spectroscopy: assessment of prognostic factors on pretreatment imaging.

To assess whether data from pre-therapeutic multiparametric magnetic resonance imaging (mpMRI) combined with three-dimensional magnetic resonance spectroscopy (3D MRS) provide prognostic factors of biochemical relapse in patients with localized prostate cancer treated by external radiotherapy or brachytherapy. In our single institution observational retrospective study we included a cohort of 230 patients treated by external radiotherapy or brachytherapy who had an initial mpMRI with 3D MRS from January 2008 to December 2015 for newly diagnosed localized prostatic cancer, proven histologically. Three trained radiologists recorded tumor characteristics, MRI T-stage and metabolic abnormalities from 3D MRS data. Univariate and multivariate Cox analyzes explored the relationship between clinical and imaging variables to highlight prognostic factors for recurrence, using biochemical relapse as the primary endpoint. mpMRI data analysis allowed to reclassify 21.7% of the patients in a MRI National Comprehensive Cancer Network (NCCN) group higher than their initial clinical T-stage, but also to detect a lesion in 78% of the patients considered as clinically T1c. After a median of follow-up of 8.7 years (IQR, 6.6-10.1) following cancer diagnosis, 36 (16%) patients developed a biochemical relapse. The multivariate Cox analysis demonstrated the existence of 3 independent factors for prediction of biochemical recurrence: extracapsular extension (ECE) (HR =3.33; 95% CI: 1.93-5.73; P<0.01), choline/citrate ratio in healthy tissue in the transition zone (TZ) (HR =2.96; 95% CI: 1.06-8.28; P=0.04) and the NCCN Magnetic Resonance Imaging classification (intermediate versus low-risk, HR =3.06; 95% CI: 1.13-8.30; P<0.01). Combination of mpMRI and 3DMRS could aid in the prognostic stratification of localized prostate cancer treated by radiotherapy or brachytherapy, by combining accurate evaluation of tumor extension, and quantification of prostate metabolism.

Awake Transcortical Approach Resection of Dominant Posterior Cingulate Gyrus Glioma: 2-Dimensional Operative Video.

Two techniques, the translongitudinal cerebral fissure and transfrontal cortical approach, can be employed to resect posterior cingulate gyrus tumors. We demonstrate the transcortical technique comprising of multimodal imaging guidance and awake brain mapping which enabled maximum safe resection of dominant cingulate gyrus glioma. The patient, a 49-yr-old female, came to clinic after experiencing headache for a month. Initial magnetic resonance imaging (MRI) scans revealed a nonenhancing lesion of the left posterior cingulate gyrus. Three-dimensional magnetic resonance spectroscopy was used to analyze the choline/N-acetyl-aspartate index (CNI) which strongly suggested a low-grade glioma diagnosis. In surgery, after creating a tailed bone window and dural opening, strip electrode was placed across the central sulcus for continuous motor evoked potential monitoring. Next, direct cortical stimulation was done to map functional cortical areas. The transcortical approach was chosen at this point because many veins hindered hemisphere retraction. Noneloquent cortical incisions were made and the tumor was carefully debunked with a cavitron ultrasonic surgical aspirator. The corpus callosum marked the deep end of dissection. Subcortical mapping combined with diffusion tensor imaging tractography-based navigation was performed to localize motor and language tracks. Intraoperative MRI evaluation confirmed a gross total resection. Pathological and molecular analysis revealed a World Health Organization Grade II IDH-wildtype Diffuse Astrocytoma diagnosis. Since the patient falls in high-risk group, she was also administered radiation and chemotherapy. Long-term cognitive evaluation follow-up of the patient showed she had good functional recovery with no obvious long-term deficits. Informed patient consent was obtained.

Magnetic resonance spectroscopy-guided stereotactic biopsy for brain lesion

To study the clinical value of magnetic resonance spectroscopy (MRS) image in stereotactic biopsy for brain lesion. From April 2008 to April 2010, 126 cases (72 male and 54 female, aged from 10 to 82 years, mean 45 years) of brain lesion which were difficult to diagnose were divided into two groups by random number table, 62 cases were executed for MRI-guided frameless stereotactic biopsy (MRI group), 64 cases were executed for MRI and MRS-guided frameless stereotactic biopsy (MRS group). Operation used MRI and Three-dimensional MRS image to locate, and used frameless CAS-R-2 robots to carry out the positioning operating. No surgery-related deaths and infections. Pathological diagnosis was 106 cases of brain tumors, 6 cases of inflammatory disease, 4 cases of tumor-like demyelinating disease and multiple sclerosis, 3 cases of neurodegenerative disease, 7 cases failed to obtain positive pathological diagnosis. The total rate of positive diagnosis was 94.4%, the positive rate in MRS-guided stereotactic biopsy group was 98.4% (63/64), the positive rate of conventional MRI-guided biopsy group was 90.3% (56/62), and there was statistically significant difference between the two groups (χ(2) = 3.92, P = 0.047). Four cases presented with postoperative complications, the complication rate was 3.2% (4/126); the complications were cerebral hemorrhage associated with aphasia, epilepsy, subcutaneous hematoma, gastrointestinal bleeding, which were improved after treatment. MRS-guided stereotactic biopsy group has a higher positive rate than MRI-guided stereotactic biopsy group, indicating that this method can improve the positive rate of diagnosis, and thus will help to formulate treatment plan for brain lesion.

Locally Advanced Prostate Cancer: Three-Dimensional Magnetic Resonance Spectroscopy to Monitor Prostate Response to Therapy

To correlate results of three-dimensional magnetic resonance spectroscopic imaging (MRSI) with prostate-specific antigen (PSA) levels and time since external beam irradiation (EBRT) in patients treated with long-term hormone therapy (HT) and EBRT for locally advanced disease to verify successful treatment by documenting the achievement of metabolic atrophy (MA). Between 2006 and 2008, 109 patients were consecutively enrolled. MA was assessed by choline and citrate peak area-to-noise-ratio <5:1. Cancerous metabolism (CM) was defined by choline-to-creatine ratio >1.5:1 or choline signal-to-noise-ratio >5:1. To test the strength of association between MRSI results and the time elapsed since EBRT (TEFRT), PSA levels, Gleason score (GS), and stage, logistic regression (LR) was performed. p value <0.05 was statistically significant. The patients' outcomes were verified in2011. MRSI documented MA in 84 of 109 and CM in 25 of 109 cases. LR showed that age, GS, stage, and initial and recent PSA had no significant impact on MRSI results which were significantly related to PSA values at the time of MRSI and to TEFRT. Patients were divided into three groups according to TEFRT: <1 year, 1-2 years, and >2 years. MA was detected in 54.1% of patients of group 1, 88.9% of group 2, and in 94.5% of group 3 (100% when PSA nadir was reached). CM was detected in 50% of patients with reached PSA nadir in group 1. Local relapse was found in 3 patients previously showing CM at long TEFRT. MA detection, indicative of successful treatment because growth of normal or abnormal cells cannot occur without metabolism, increases with decreasing PSA levels and increasing time on HT after EBRT. This supports long-term HT in advanced prostate cancer. Larger study series are needed to assess whether MRSI could predict local relapse by detecting CM at long TEFRT.

Histopathological validation of a three-dimensional magnetic resonance spectroscopy index as a predictor of tumor presence.

Data obtained preoperatively from three-dimensional (3D)/proton magnetic resonance (MR) spectroscopy were compared with the results of histopathological assays of tissue biopsies obtained during surgery to verify the sensitivity and specificity of a choline-containing compound-N-acetylaspartate index (CNI) used to distinguish tumor from nontumorous tissue within T2-hyperintense and contrast-enhancing lesions of patients with untreated gliomas. The information gleaned from the biopsy correlation study was used to test the hypothesis that there is metabolically active tumor in nonenhancing regions of the T2-hyperintense lesion that can be detected using MR spectroscopy. Patients suspected of harboring a glioma underwent 3D MR spectroscopy during their preoperative MR imaging examination. Surgical navigation techniques were used to record the location of tissue biopsies collected during open resection of the tumor. A receiver operating curve analysis of the CNI and histological characteristics of specimens at each biopsy location was performed to determine the optimal threshold of the CNI required to separate tumor from nontumorous tissue. Histograms of the CNIs within enhancing and nonenhancing regions of lesions appearing on MR images were generated to determine the spatial distribution of CNIs consistent with tumor. Biopsy samples containing tumor were distinguished from those containing a mixture of normal, edematous, gliotic, and necrotic tissue with 90% sensitivity and 86% specificity by using a CNI threshold of 2.5. The CNIs of nontumorous specimens were significantly different from those of biopsy specimens containing Grade II (p < 0.03), Grade III (p < 0.005), and Grade IV (p < 0.01) tumors. On average, one third to one half of the T2-hyperintense lesion outside the contrast-enhancing lesion contained CNI greater than 2.5.

Metabolic imaging of low-grade gliomas with three-dimensional magnetic resonance spectroscopy

Purpose: The role of radiotherapy (RT) seems established for patients with low-grade gliomas with poor prognostic factors. Three-dimensional (3D) magnetic resonance spectroscopy imaging (MRSI) has been reported to be of value in defining the extent of glioma infiltration. We performed a study examining the impact MRSI would have on the routine addition of 2–3-cm margins around MRI T2-weighted hyperintensity to generate the treatment planning clinical target volume (CTV) for low-grade gliomas. Methods and Materials: Twenty patients with supratentorial gliomas WHO Grade II (7 astrocytomas, 6 oligoastrocytomas, 7 oligodendrogliomas) underwent MRI and MRSI before surgery. The MRI was contoured manually; the regions of interest included T2 hyperintensity and, if present, regions of contrast enhancement on T1-weighted images. The 3D-MRSI peak parameters for choline and N-acetyl-aspartate, acquired voxel-by-voxel, were categorized using a choline/ N-acetyl-aspartate index (CNI), a tool for quantitative assessment of tissue metabolite levels, with CNI 2 being the lowest value corresponding to tumor. CNI data were aligned to MRI and displayed as 3D contours. The relationship between the anatomic and metabolic information on tumor extent was assessed by comparing the CNI contours and other MRSI-derived metabolites to the MRI T2 volume. Results: The limitations in the size of the region “excited” meant that MRSI could be used to evaluate only a median 68% of the T2 volume (range 38–100%), leaving the volume T2c. The CNI 2 volume (median 29 cm 3, range 10–73) was contained totally within the T2c in 55% of patients. In the remaining patients, the volume of CNI 2 extending beyond the T2c was quite small (median 2.3 cm 3, range 1.4–5.2), but was not distributed uniformly about the T2c, extending up to 22 mm beyond it. Two patients demonstrated small regions of contrast enhancement corresponding to the regions of highest CNI. Other metabolites, such as creatine and lactate, seem useful for determining less and more radioresistant areas, respectively. Conclusion: Metabolically active tumor, as detected by MRSI, is restricted mainly to the T2 hyperintensity in low-grade gliomas, but can extend outside it in a limited and nonuniform fashion up to 2 cm. Therefore, a CTV including T2 and areas of CNI extension beyond the T2 hyperintensity would result in a reduction in the size and a change in the shape of the standard clinical target volumes generated by adding uniform margins of 2–3 cm to the T2 hyperintensity.