Application value of 3T ¹H-magnetic resonance spectroscopy in diagnosing breast tumors

The history of magnetic resonance imaging and its reflections in Acta Radiologica

The first reports in Acta Radiologica on magnetic resonance imaging (MRI) were published in 1984, four years after the first commercial MR scanners became available. For the first two years, all MR papers originated from the USA. Nordic contributions started in 1986, and until 2020, authors from 44 different countries have published MR papers in Acta Radiologica. Papers on MRI have constituted, on average, 30%-40% of all published original articles in Acta Radiologica, with a high of 49% in 2019. The MR papers published since 1984 document tremendous progress in several areas such as magnet and coil design, motion compensation techniques, faster image acquisitions, new image contrast, contrast-enhanced MRI, functional MRI, and image analysis. In this historical review, all of these aspects of MRI are discussed and related to Acta Radiologica papers.

Are there differences in the biochemical profile of bilateral normal testes? A 3.0 T 1H-MR spectroscopy study

Bilateral normal testes asymmetry represents an interesting phenomenon. The aim was to assess possible differences in the biochemical profile of bilateral normal testes by 3.0 T proton magnetic resonance spectroscopy (1H-MRS). Twenty-one men were examined with scrotal 3.0 T MRI, including a single-voxel point-resolved spectroscopy sequence. MR spectra were obtained by placing a volume of interest in the middle of each normal testis. Normalised metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to creatine (Cr) concentration, were compared between bilateral normal testes using Mann-Whitney U test. 1H-MRS allowed the detection of certain testicular metabolites, including total choline, Cr, myo-inositol, Glx, total lipids and macromolecules resonating at 0.9, 1.3 and 2.0 ppm. Normal left testis had higher median normalised concentrations of Glx (p = .002) and lactate (p = .041) compared with the normal right testis. Differences in concentrations of Glx were attributed to differences in glutamate (p = .020). Normal testes asymmetry is confirmed in this study by differences in the biochemical testicular profile, as assessed by 3.0 T 1H-MRS. Increase in levels of glutamate and lactate in normal left testis should be correlated with changes in metabolic pathways, specifically glycometabolism and amino acid metabolism.

In vivo MR spectroscopy for breast cancer diagnosis

Breast cancer is a significant health concern in females, worldwide. In vivo proton (1H) MR spectroscopy (MRS) has evolved as a non-invasive tool for diagnosis and for biochemical characterization of breast cancer. Water-to-fat ratio, fat and water fractions and choline containing compounds (tCho) have been identified as diagnostic biomarkers of malignancy. Detection of tCho in normal breast tissue of volunteers and in lactating females limits the use of tCho as a diagnostic marker. Technological developments like high-field scanners, multi channel coils, pulse sequences with water and fat suppression facilitated easy detection of tCho. Also, quantification of tCho and its cut-off for objective assessment of malignancy have been reported. Meta-analysis of in vivo 1H MRS studies have documented the pooled sensitivities and the specificities in the range of 71-74% and 78-88%, respectively. Inclusion of MRS has been shown to enhance the diagnostic specificity of MRI, however, detection of tCho in small sized lesions (≤1 cm) is challenging even at high magnetic fields. Potential of MRS in monitoring the effect of chemotherapy in breast cancer has also been reported. This review briefly presents the potential clinical role of in vivo 1H MRS in the diagnosis of breast cancer, its current status and future developments.

Role of diffusion weighted imaging and magnetic resonance spectroscopy in breast cancer patients with indeterminate dynamic contrast enhanced magnetic resonance imaging findings

PURPOSE

Dynamic contrast enhanced MRI (DCEMRI), diffusion weighted imaging (DWI) and in vivo proton (¹H) magnetic resonance spectroscopy (MRS) provides functional and molecular nature of breast cancer. This study evaluates the potential of the combination of three MR parameters [curve kinetics, apparent diffusion coefficient (ADC) and total choline (tCho) concentration] determined from these techniques in increasing the sensitivity of breast cancer detection.

METHODS

MR investigations were carried out at 1.5 T on 56 patients with cytologically/histologically confirmed breast carcinoma. Single-voxel MRS was used to determine the tCho concentration. 3D FLASH was used for DCEMRI while single shot EPI based DWI was used for ADC determination.

RESULTS

On DCEMRI, one patient showed type I curve, while 8 showed type II and 47 showed type III curve thus giving a sensitivity of 83.9% as detection rate of malignancy. tCho concentration was above cut-off value (2.54 mmol/kg) for 50/56 cases giving a sensitivity of 89.3%. Among 9 indeterminate DCEMRI cases, tCho showed malignancy in 6 cases with type II curve. DWI detected malignancy in 54/56 cases that included 9 cases that were false negative on DCEMRI, yielding a sensitivity of 96.4%. A total of 54 cases showed malignancy when any two of the three MR parameters was positive for malignancy yielding a sensitivity of 96.4% while it increased to 100% when any one parameters showed positive result.

CONCLUSION

DWI showed highest sensitivity of detection compared to DCEMRI and MRS. Multi-parametric approach yielded 96.4% and 100% sensitivity when any two or one of the three parameters was taken as positive for malignancy, respectively. Also the results demonstrated that addition of DWI and MRS play a significant role in establishing the final diagnosis of malignancy, especially in cases where DCEMRI is indeterminate.

Efficacy of single voxel 1H MR spectroscopic imaging at 3T for the differentiation of benign and malign breast lesions

PURPOSE

The aim of our study was to evaluate the effect of 1H Magnetic Resonance Spectroscopy (MRS) in differentiating breast lesions.

MATERIALS AND METHODS

Single voxel 1H Magnetic Resonance Spectroscopy (1H-MRS) was performed with 3T magnet in 45 women. The choline cut off point was set semi-quantitavely. Sensitivity, specificity and accuracy of MRS were calculated.

RESULTS

Twenty-four of 25 (96%) malignant and 9 of 26 (35%) benign lesions had choline peak. With the use cutoff value of 19,5 MRS provided a 96% sensitivity, 65% specificity and 80% accuracy.

CONCLUSION

MRS has a high diagnostic accuracy in differentiating breast lesions.

Metabolite profiling in retinoblastoma identifies novel clinicopathological subgroups

BACKGROUND

Tumour classification, based on histopathology or molecular pathology, is of value to predict tumour behaviour and to select appropriate treatment. In retinoblastoma, pathology information is not available at diagnosis and only exists for enucleated tumours. Alternative methods of tumour classification, using noninvasive techniques such as magnetic resonance spectroscopy, are urgently required to guide treatment decisions at the time of diagnosis.

METHODS

High-resolution magic-angle spinning magnetic resonance spectroscopy (HR-MAS MRS) was undertaken on enucleated retinoblastomas. Principal component analysis and cluster analysis of the HR-MAS MRS data was used to identify tumour subgroups. Individual metabolite concentrations were determined and were correlated with histopathological risk factors for each group.

RESULTS

Multivariate analysis identified three metabolic subgroups of retinoblastoma, with the most discriminatory metabolites being taurine, hypotaurine, total-choline and creatine. Metabolite concentrations correlated with specific histopathological features: taurine was correlated with differentiation, total-choline and phosphocholine with retrolaminar optic nerve invasion, and total lipids with necrosis.

CONCLUSIONS

We have demonstrated that a metabolite-based classification of retinoblastoma can be obtained using ex vivo magnetic resonance spectroscopy, and that the subgroups identified correlate with histopathological features. This result justifies future studies to validate the clinical relevance of these subgroups and highlights the potential of in vivo MRS as a noninvasive diagnostic tool for retinoblastoma patient stratification.

1H-MRS evaluation of breast lesions by using total choline signal-to-noise ratio as an indicator of malignancy: a meta-analysis

The aim of this study was to evaluate the diagnostic performance of the use of total choline signal-to-noise ratio (tCho SNR) criteria in MRS studies for benign/malignant discrimination of focal breast lesions. We conducted (1) a meta-analysis based on 10 studies including 480 malignant breast lesions and 312 benign breast lesions and (2) a subgroup meta-analysis of tCho SNR ≥ 2 as cutoff for malignancy based on 7 studies including 371 malignant breast lesions and 239 benign breast lesions. (1) The pooled sensitivity and specificity of proton MRS with tCho SNR were 0.74 (95 % CI 0.69-0.77) and 0.76 (95 % CI 0.71-0.81), respectively. The PLR and NLR were 3.67 (95 % CI 2.30-5.83) and 0.25 (95 % CI 0.14-0.42), respectively. From the fitted SROC, the AUC and Q* index were 0.89 and 0.82. Publication bias was present (t = 2.46, P = 0.039). (2) Meta-regression analysis suggested that neither threshold effect nor evaluated covariates including strength of field, pulse sequence, TR and TE were sources of heterogeneity (all P value >0.05). (3) Subgroup meta-analysis: The pooled sensitivity and specificity were 0.79 and 0.72, respectively. The PLR and NLR were 3.49 and 0.20, respectively. The AUC and Q* index were 0.92 and 0.85. The use of tCho SNR criteria in MRS studies was helpful for differentiation between malignant and benign breast lesions. However, pooled diagnostic measures might be overestimated due to publication bias. A tCho SNR ≥ 2 as cutoff for malignancy resulted in higher diagnostic accuracy.

In vivo post-contrast 1H-MRS evaluation of malignant and benign breast lesions: a meta-analysis

The aim of this study is to perform a meta-analysis to evaluate the diagnostic performance of the in vivo post-contrast proton magnetic resonance spectroscopy (MRS) for benign/malignant discrimination of focal breast lesions. Sixteen studies with a total of 661 malignant breast lesions and 388 benign breast lesions were included. The pooled sensitivity and specificity of post-contrast 1H-MRS were 74 % (95 % confidence interval (CI) 70-77 %) and 78 % (95 % CI 73-82 %), respectively. The positive likelihood ratio (PLR) and the negative likelihood ratio (NLR) were 4.00 (95 % CI 2.74-5.84) and 0.25 (95 % CI 0.17-0.37), respectively. From the fitted summary receiver operating characteristics curve (SROC), the AUC and Q* index were 0.89 and 0.83. Publication bias was present (t = 2.43, P = 0.029). Meta-regression analysis suggested that neither threshold effect nor evaluated covariates including method of choline analysis, strength of field, pulse sequence, repetition time (TR), and time interval were sources of heterogeneity (all P values >0.05). In vivo post-contrast 1H-MRS was useful for differentiation between malignant and benign focal breast lesions. However, pooled diagnostic measures might be overestimated. The standardization of the acquisition protocol as well as the post-processing method for post-contrast proton MRS need to be established for the future study.

Differential diagnosis between malignant and benign breast lesions using single-voxel proton MRS: a meta-analysis

OBJECTIVES

We aim to investigate the diagnostic capability of single-voxel proton MR spectroscopy (MRS) for benign/malignant discrimination of focal breast lesions with a meta-analysis.

MATERIALS AND METHODS

The meta-analysis included a total of 750 malignant breast lesions and 419 benign breast lesions from eighteen studies.

RESULTS

The pooled sensitivity and specificity of MRS were 0.71 (95 % CI 0.68-0.74) and 0.85 (95 % CI 0.81-0.88), respectively. The positive likelihood ratio and negative LR were 4.11 (95 % CI 3.11-5.43) and 0.25 (95 % CI 0.17-0.36), respectively. The P value for χ(2) heterogeneity for all pooled estimates was <0.05. From the fitted summary receiver operating characteristics curve, AUC was 0.89 and Q* was 0.84. Asymmetrical in funnel plots indicated there may be publication bias (t = 2.85, P = 0.012). The meta-regression analysis indicated that neither threshold effect nor evaluated covariates that include strength of field, scanning technique (PRESS or STEAM), repetition time, NSA, and pre- or post-contrast agent were the sources of heterogeneity (all P value >0.05).

CONCLUSIONS

Single-voxel proton MRS was useful for differentiation between malignant and benign breast lesions. However, pooled diagnostic measures might be overestimated. The standardization of the acquisition protocol for MRS across the multicenter trials is recommended.