Quantitative study of liver magnetic resonance spectroscopy quality at 3T using body and phased array coils with physical analysis and clinical evaluation

MR Spectroscopy for Detecting Fumarate Hydratase Deficiency in Hereditary Leiomyomatosis and Renal Cell Carcinoma Syndrome

Background Noninvasive in vivo detection of fumarate accumulation may help identify fumarate hydratase deficiency in renal cancer related to hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome. Purpose To investigate the feasibility of MR spectroscopy (MRS) in detecting elevated fumarate levels in HLRCC-associated renal cancers. Materials and Methods This study included an experimental xenograft mouse model and prospective clinical cohort. First, MRS was performed on patient-derived tumor xenograft models and control models to detect fumarate. Then, consecutive participants with clinical suspicion of HLRCC-associated renal tumors were enrolled. For the detection of fumarate, MRS results were classified as detected, borderline, undetected, or technical failure. The sensitivity, specificity, and accuracy of MRS for diagnosing HLRCC-associated renal cancer were assessed. The signal-to-noise ratio (SNR) of the fumarate peak was calculated and evaluated with receiver operating characteristic curve analysis. Results Fumarate peaks were detected at 6.54 parts per million in all three patient-derived xenograft models. A total of 38 participants (21 men; mean age, 47 years [range, 18-71 years]) with 46 lesions were analyzed. All primary HLRCC-associated renal cancers showed a fumarate peak; among the seven metastatic HLRCC-associated lesions, a fumarate peak was detected in three lesions and borderline in two. When only detected peaks were regarded as positive findings, the sensitivity, specificity, and accuracy of MRS at the lesion level were 69% (nine of 13 lesions), 100% (33 of 33 lesions), and 91% (42 of 46 lesions), respectively. When borderline peaks were also included as a positive finding, the sensitivity, specificity, and accuracy reached 85% (11 of 13 lesions), 88% (29 of 33 lesions), and 87% (40 of 46 lesions), respectively. The SNR of fumarate showed an area under the receiver operating characteristic curve of 0.87 for classifying HLRCC-associated tumors. Conclusion MR spectroscopy of fumarate was sensitive and specific for hereditary leiomyomatosis and renal cell carcinoma-associated tumors. © RSNA, 2022 Online supplemental material is available for this article.

Magnetic Resonance Spectroscopy of Hepatic Fat from Fundamental to Clinical Applications

The number of individuals suffering from fatty liver is increasing worldwide, leading to interest in the noninvasive study of liver fat. Magnetic resonance spectroscopy (MRS) is a powerful tool that allows direct quantification of metabolites in tissue or areas of interest. MRS has been applied in both research and clinical studies to assess liver fat noninvasively in vivo. MRS has also demonstrated excellent performance in liver fat assessment with high sensitivity and specificity compared to biopsy and other imaging modalities. Because of these qualities, MRS has been generally accepted as the reference standard for the noninvasive measurement of liver steatosis. MRS is an evolving technique with high potential as a diagnostic tool in the clinical setting. This review aims to provide a brief overview of the MRS principle for liver fat assessment and its application, and to summarize the current state of MRS study in comparison to other techniques.

Tumor enhancement of colorectal liver metastases on preoperative gadobutrol-enhanced MRI at 5 minutes post-contrast injection is associated with overall survival post-hepatectomy

Previous studies have demonstrated that target tumor enhancement (TTE) of colorectal cancer liver metastases (CRCLM) on 10-minute delayed phase gadobutrol-enhanced MRI is associated with overall survival post-hepatectomy. The purpose of this study was to determine whether TTE of CRCLM on preoperative gadobutrol-enhanced MRI measured at 5-minute delayed phase is also associated with overall survival. We performed a single-institution, REB-approved, retrospective study of 121 patients with CRCLM who had received a clinical gadobutrol-enhanced MRI after treatment with chemotherapy and prior to liver surgery between January 1, 2006 and December 31, 2012. The TTE of the colorectal liver metastases (CRLM) on 5-minute delayed phase was determined. Kaplan-Meier and Cox-regression survival analyses were used in order to determine the association between TTE on 5-minute delayed phase and overall survival, after adjusting for known prognostic variables. TTE of chemotherapy-treated CRLM on gadobutrol-enhanced MRI at 5-minute post-contrast injection is associated with overall survival post-hepatectomy. On Kaplan-Meier survival analysis, there was a significant difference in overall survival between strong and weak TTE groups (log-rank P=0.009) with 74.4% survival at 36 months in the strong TTE group compared to only 44.6% in the weak TTE group. On Cox-regression analysis, the adjusted hazard ratio of death for patients with low TTE was 0.40 (95% CI: 0.18-0.90, P=0.026), after adjusting for known prognostic variables. This study provides preliminary evidence that tumor enhancement of CRLM at 5 minutes post-contrast injection on gadobutrol-enhanced MRI may provide preoperative prognostic information. This may be helpful for risk stratification of patients for surgery.

Late gadolinium enhancement of colorectal liver metastases post-chemotherapy is associated with tumour fibrosis and overall survival post-hepatectomy

Purpose

To determine whether late gadolinium MRI enhancement of colorectal liver metastases (CRCLM) post-chemotherapy is associated with tumour fibrosis and survival post-hepatectomy.

Materials and methods

The institutional review board approved this retrospective cohort study and waived the requirement for informed consent. A cohort of 121 surgical patients who received preoperative MRI after chemotherapy between 2006-2012 was included in this study. Target tumour enhancement (TTE), defined as the mean contrast-to-noise ratio of up to two target lesions on late-phase gadobutrol-enhanced MRI, was determined by two independent raters. The average TTE was correlated with tumour fibrosis on post-hepatectomy specimens using Spearman correlation and with survival post-hepatectomy using Kaplan-Meier and Cox regression. Inter-rater reliability was determined using relative intra-class correlation coefficients.

Results

In the surgical cohort (mean age: 63.0 years; male: 58%), TTE was associated with tumour fibrosis (r = 0.43, p < 0.001). Strong TTE was associated with improved survival compared to weak TTE (3-year survival: 88.4% vs. 58.8%, p = 0.003) with a hazard ratio of 0.32 (95% CI: 0.14-0.75, p = 0.008), after taking into account known prognostic variables. Inter-rater reliability was very good with a relative intraclass correlation of 0.84 (95% CI: 0.77-0.89).

Conclusion

Late gadolinium MRI enhancement of CRCLM post-chemotherapy is associated with tumour fibrosis and survival.

Key Points

• MRI enhancement of colorectal liver metastases is associated with survival post-hepatectomy

• MRI enhancement of chemotherapy-treated colorectal liver metastases correlates with tumour fibrosis

• Measuring late MRI enhancement using target tumour enhancement is reliable

Magnetic Resonance Spectroscopy and its Clinical Applications: A Review

In vivo NMR spectroscopy is known as magnetic resonance spectroscopy (MRS). MRS has been applied as both a research and a clinical tool in order to detect visible or nonvisible abnormalities. The adaptability of MRS allows a technique that can probe a wide variety of metabolic uses across different tissues. Although MRS is mostly applied for brain tissue, it can be used for detection, localization, staging, tumour aggressiveness evaluation, and tumour response assessment of breast, prostate, hepatic, and other cancers. In this article, the medical applications of MRS in the brain, including tumours, neural and psychiatric disorder studies, breast, prostate, hepatic, gastrointestinal, and genitourinary investigations have been reviewed.