Evaluation of the INTERPRET decision-support system: can it improve the diagnostic value of magnetic resonance spectroscopy of the brain?

Purpose

We evaluated in a clinical setting the INTERPRET decision-support system (DSS), a software generated to aid in MRS analysis to achieve a specific diagnosis for brain lesions.

Methods

The material consisted of 100 examinations of focal intracranial lesions with confirmed diagnoses. MRS was obtained at 1.5 T using TE 20–30 ms. Data were processed with the LCModel for conventional analysis. The INTERPRET DSS 3.1. was used to obtain specific diagnoses. MRI and MRS were reviewed by one interpreter. DSS analysis was made by another interpreter, in 80 cases by two interpreters. The diagnoses were compared with the definitive diagnoses. For comparisons between DSS, conventional MRS analysis, and MRI, the diagnoses were categorised: high-grade tumour, low-grade tumour, non-neoplastic lesion.

Results

Interobserver agreement in choosing the diagnosis from the INTERPRET database was 75%. The diagnosis was correct in 38/100 cases, incorrect in 57 cases. No good match was found in 5/100 cases. The diagnostic category was correct with DSS/conventional MRS/MRI in 67/58/52 cases, indeterminate in 5/8/20 cases, incorrect in 28/34/28 cases. Results with DSS were not significantly better than with conventional MRS analysis. All definitive diagnoses did not exist in the INTERPRET database. In the 61 adult patients with the diagnosis included in the database, DSS/conventional MRS/MRI yielded a correct diagnosis category in 48/32/29 cases (DSS vs conventional MRS: p = 0.002, DSS vs MRI: p = 0.0004).

Conclusion

Use of the INTERPRET DSS did not improve MRS categorisation of the lesions in the unselected clinical cases. In adult patients with lesions existing in the INTERPRET database, DSS improved the results, which indicates the potential of this software with an extended database.

Electronic supplementary material

The online version of this article (10.1007/s00234-018-2129-7) contains supplementary material, which is available to authorized users.

Placental perfusion in normal pregnancy and early and late preeclampsia: a magnetic resonance imaging study

OBJECTIVE

Our primary aim was to investigate if women with early or late preeclampsia have different placental perfusion compared with normal pregnancies. A secondary aim was to investigate if placental perfusion changes with increasing gestational age in normal pregnancy.

METHODS

The study population included thirteen women with preeclampsia (five with early and eight with late preeclampsia) and nineteen women with normal pregnancy (ten with early and nine with late pregnancy). Early was defined as <34 weeks and late as ≥ 34 weeks gestation. All women underwent a magnetic resonance imaging (MRI) examination including a diffusion weighted sequence at 1.5 T. The perfusion fraction was calculated.

RESULTS

Women with early preeclampsia had a smaller placental perfusion fraction (p = 0.001) and women with late preeclampsia had a larger placental perfusion fraction (p = 0.011), compared to women with normal pregnancies at the corresponding gestational age. The placental perfusion fraction decreased with increasing gestational age in normal pregnancies (p = 0.001).

CONCLUSION

Both early and late preeclampsia differ in placental perfusion from normal pregnant women. Observed differences are however in the opposite direction, suggesting differences in pathophysiology. Placental perfusion decreases with increasing gestational age in normal pregnancy.

Reproducibility of hepatic triglyceride content assessment in normals using localized magnetic resonance spectroscopy

AIM

To investigate the reproducibility of measurements of hepatic triglyceride content (HTGC) in subjects with normal HTGC using localized (1)H-magnetic resonance spectroscopy ((1)H-MRS) and a clinical 1.5T scanner.

METHODS

The (1)H-MRS acquisition was performed with a common protocol using the whole-body coil and no respiratory triggering. An upper limit of normal HTGC of 5.56% was used. Duplicate measurements, including subject repositioning, were acquired from 23 subjects, 19 of whom had a normal HTGC.

RESULTS

The mean coefficient of variation (CV) from the duplicate measurements was 14.8% (20.5% before exclusion of a subject who was considered to be an outlier). Mean CVs of subgroups below and above the 1% HTGC limit were 19.8 and 7.0 respectively.

CONCLUSIONS

The mean CV calculated in subjects with HTGC in the normal range was found to be higher than CVs of wide range HTGC groups reported in the literature. It is concluded that the reproducibility of HTGC measurements using (1)H-MRS depends on the HTGC range. These findings are of importance in reproducibility studies and in estimations of required study group sizes.

Assessment of lipids in skeletal muscle by high-resolution spectroscopic imaging using fat as the internal standard: comparison with water referenced spectroscopy

The main purpose of the study was to compare proton (1H) single-voxel MR spectroscopy (MRS) with high-spatial-resolution spectroscopic imaging (MRSI) to determine the lipid content in human skeletal muscle. Unsuppressed water line was used as a concentration reference in the processing of single-voxel spectra. The spectrum from yellow bone marrow with a 100% fat content and probe with the vegetable oil served as internal and external reference for high-spatial-resolution MRSI, respectively. Very good correlation was found between lipid concentrations measured by water referenced single-voxel MRS and high-spatial-resolution MRSI with yellow bone marrow as the internal standard. Excellent correlation was found between total lipid concentrations estimated by high-spatial-resolution MRSI with vegetable oil as the external fat standard and yellow bone marrow as the internal reference. From comparison of single-voxel MRS and MRSI approaches, it follows that relaxation correction of the reference water and methylene fat line is inevitable in processing the standard single-voxel spectra. The high-resolution MRSI approach is recommended to avoid the problem of relaxation corrections and enables using vegetable oil as the external fat standard.