1H magnetic resonance spectroscopy of preinvasive and invasive cervical cancer: In vivo-ex vivo profiles and effect of tumor load

1H magnetic resonance spectroscopy in the differentiation between low- and high-grade cervical carcinoma: is it efficient?

Purpose

To evaluate the extent to which magnetic resonance spectroscopy (MRS) lipid metabolites are accurate in predicting high-grade cervical cancer.

Material and methods

This prospective single-centre pilot study included 20 cases with pathologically proven cervical cancer. They underwent pelvic magnetic resonance imaging (MRI) with MRS. Two radiologists, blinded to the histopathological results, with 10 years of experience in gynaecological imaging, independently analysed the MRI images and MRS curves, and a third one resolved any disagreement. Using the histopathological results as a standard test, the receiver operating characteristics (ROC) curve was utilised to calculate the optimal lipid peak (1.3 ppm) cutoff for predicting high-grade cervical cancer. The difference in MRS metabolites between low- and high-grade cervical cancer groups was estimated using the Mann-Whitney test.

Results

The study included 11 high-grade and nine low-grade cervical cancer cases based on the histopathological evaluation. A lipid (1.3 ppm) peak of 29.9 was the optimal cutoff for predicting high-grade cervical cancer with 100% sensitivity, 77.8%, specificity, and 90% accuracy. Moreover, there was a significant difference between low- and high-grade cervical cancer cases concerning lipid peak at 0.9 ppm, lipid peak at 1.3 ppm, and the peak of choline with (p-value 0.025, 0.001, and 0.023), respectively.

Conclusions

MRS might be considered a useful imaging technique for assessing the grade of cervical cancer and improving the planning of treatment. It shows a good diagnostic accuracy. Therefore, it can be adopted in clinical practice for better patient outcome.

Post treatment imaging in patients with local advanced cervical carcinoma

Cervical cancer (CC) is the fourth leading cause of death in women worldwide and despite the introduction of screening programs about 30% of patients presents advanced disease at diagnosis and 30-50% of them relapse in the first 5-years after treatment. According to FIGO staging system 2018, stage IB3-IVA are classified as locally advanced cervical cancer (LACC); its correct therapeutic choice remains still controversial and includes neoadjuvant chemo-radiotherapy, external beam radiotherapy, brachytherapy, hysterectomy or a combination of these modalities. In this review we focus on the most appropriated therapeutic options for LACC and imaging protocols used for its correct follow-up. We explore the imaging findings after radiotherapy and surgery and discuss the role of imaging in evaluating the response rate to treatment, selecting patients for salvage surgery and evaluating recurrence of disease. We also introduce and evaluate the advances of the emerging imaging techniques mainly represented by spectroscopy, PET-MRI, and radiomics which have improved diagnostic accuracy and are approaching to future direction.

The contribution of the 1H-MRS lipid signal to cervical cancer prognosis: a preliminary study

Background

The aim of this study was to investigate the role of the lipid peak derived from ¹H magnetic resonance (MR) spectroscopy in assessing cervical cancer prognosis, particularly in assessing response to neoadjuvant chemotherapy (NACT) of locally advanced cervical cancer (LACC).

Methods

We enrolled 17 patients with histologically proven cervical cancer who underwent 3-T MR imaging at baseline. In addition to conventional imaging sequences for pelvic assessment, the protocol included a single-voxel point-resolved spectroscopy (PRESS) sequence, with repetition time of 1,500 ms and echo times of 28 and 144 ms. Spectra were analysed using the LCModel fitting routine, thus extracting multiple metabolites, including lipids (Lip) and total choline (tCho). Patients with LACC were treated with NACT and reassessed by MRI at term. Based on tumour volume reduction, patients were classified as good responder (GR; tumour volume reduction > 50%) and poor responder or nonresponder (PR-or-NR; tumour volume reduction ≤ 50%).

Results

Of 17 patients, 11 were LACC. Of these 11, only 6 had both completed NACT and had good-quality ¹H-MR spectra; 3 GR and 3 PR-or-NR. A significant difference in lipid values was observed in the two groups of patients, particularly with higher Lip values and higher Lip/tCho ratio in PR-NR patients (p =0.040). A significant difference was also observed in choline distribution (tCho), with higher values in GR patients (p = 0.040).

Conclusions

Assessment of lipid peak at ¹H-MR spectroscopy could be an additional quantitative parameter in predicting the response to NACT in patients with LACC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41747-022-00300-1.

Underdiagnosis of early cervical cancer with an invisible cervical transformation zone in an elderly patient: A case report

The treatment of cervical intraepithelial neoplasia (CIN) can result in under- or overtreatment. The current report describes a case of undertreatment of a cervical tumor. A 72-year-old woman was preoperatively diagnosed with CIN3. Following surgery, the final diagnosis of the excised specimen was keratinizing squamous cell carcinoma that measured 2.5 cm in size. The exocervical margin and deep margin were negative. The patient received adjuvant therapy with concurrent chemoradiotherapy and never had disease recurrence. In elderly patients, making an accurate preoperative diagnosis based on specimens from cervical biopsies with or without colposcopy is difficult. MRI may be an accurate preoperative indicator of early cervical tumor, although some studies have demonstrated that MRI has a limitation with respect to its diagnostic ability. Other studies have reported that it is necessary to perform conization prior to hysterectomy. Physicians must reconsider the determined preoperative diagnosis of an early cervical tumor and establish standard guidelines for deciding when to use surgical treatment in elderly patients.

Clinical value of N-acetyl mucinous compounds and lipid peaks in differentiating benign and malignant ovarian mucinous tumors by MR spectroscopy

PURPOSE

To retrospectively evaluate the clinical significance of the peaks of N-acetyl mucinous compounds (NAMC) at 2 ppm and lipid at 1.3 ppm in in-vivo proton magnetic resonance (MR) spectroscopy for distinguishing benign and malignant mucinous tumors in patients with ovarian masses.

METHODS

MR spectroscopy was performed in patients with pathologically diagnosed mucinous ovarian tumors at 3 T MRI system. The peaks of NAMC, lipid, and total choline compounds (tCho) were classified into three classes in comparison with the noise level by visual estimation. The NAMC concentration was quantified relative to unsuppressed water by using LCModel analysis.

RESULTS

A total of 27 ovarian mucinous tumors in 27 patients were included in this study. The NAMC peak was observed in all 27 mucinous tumors, and the lipid peak was observed in 14 of 27 tumors: 1 of 9 benign tumors (11%), and 13 of 18 malignant tumors (11 borderline malignancies and 7 carcinomas) (72%). The presence of the lipid peak for the diagnosis of malignant mucinous tumor showed generally better diagnostic ability than MR imaging, with a sensitivity of 72%, specificity of 89%, accuracy of 78%, PPV of 93%, and NPV of 62%. The concentration of the NAMC in malignant mucinous tumors tended to be higher than that in benign mucinous tumors, but there was no statistically significant difference.

CONCLUSIONS

The bimodal peaks of NAMC and lipid are suggestive of malignant mucinous tumors, and the presence of the lipid peak may be useful in distinguishing benign from malignant ovarian mucinous tumors.

Focus on the glycerophosphocholine pathway in choline phospholipid metabolism of cancer

Activated choline metabolism is a hallmark of carcinogenesis and tumor progression, which leads to elevated levels of phosphocholine and glycerophosphocholine in all types of cancer tested so far. Magnetic resonance spectroscopy applications have played a key role in detecting these elevated choline phospholipid metabolites. To date, the majority of cancer-related studies have focused on phosphocholine and the Kennedy pathway, which constitutes the biosynthesis pathway for membrane phosphatidylcholine. Fewer and more recent studies have reported on the importance of glycerophosphocholine in cancer. In this review article, we summarize the recent literature on glycerophosphocholine metabolism with respect to its cancer biology and its detection by magnetic resonance spectroscopy applications.

Proton MRS of cervical cancer at 7 T

The differentiation grade of cervical cancer is histologically assessed by examining biopsies or surgical specimens. MRS is a highly sensitive technique that images tissue metabolism and can be used to increase the specificity of tissue characterization in a non-invasive manner. We aim to explore the feasibility of using in vivo ¹ H-MRS at 7 T in women with cervical cancer to study tissue fatty acid composition. 10 women with histologically proven Stage IB1-IIB cervical cancer were scanned with a whole-body 7 T MR system with a multi-transmit system and an internal receive only monopole antenna. A STEAM sequence was used to obtain ¹ H-MRS data. Fatty acid resonances were fitted with Lorentzian curves and the 2.1 ppm/1.3 ppm ratios were calculated. ¹ H-MRS data showed fatty acid signals resonating at 2.1 ppm, 1.9 ppm, 1.5 ppm, 1.3 ppm and 0.9 ppm. Mean 2.1/1.3 ppm ratios were 0.019 ± 0.01, 0.021 ± 0.006, 0.12 ± 0.089 and 0.39 ± 0.27 for normal, Grade I, Grade II and Grade III groups respectively. Poorly differentiated tumor tissue (Grade III) showed elevated fatty acid ratios when compared with the well differentiated tumor (Grade I) or normal tissue. ¹ H-MRS in cervical cancer at 7 T is feasible and individual fatty acid signals were detected. In addition, poorly differentiated tumors show more fatty acid unsaturation. The 2.1 ppm/1.3 ppm ratio has potential for tumor characterization in a non-invasive manner for uterine cervical cancer.

Applications of high-resolution magic angle spinning MRS in biomedical studies II-Human diseases

High-resolution magic angle spinning (HRMAS) MRS is a powerful method for gaining insight into the physiological and pathological processes of cellular metabolism. Given its ability to obtain high-resolution spectra of non-liquid biological samples, while preserving tissue architecture for subsequent histopathological analysis, the technique has become invaluable for biochemical and biomedical studies. Using HRMAS MRS, alterations in measured metabolites, metabolic ratios, and metabolomic profiles present the possibility to improve identification and prognostication of various diseases and decipher the metabolomic impact of drug therapies. In this review, we evaluate HRMAS MRS results on human tissue specimens from malignancies and non-localized diseases reported in the literature since the inception of the technique in 1996. We present the diverse applications of the technique in understanding pathological processes of different anatomical origins, correlations with in vivo imaging, effectiveness of therapies, and progress in the HRMAS methodology.

Carcinosarcoma of the uterus: MRI findings including diffusion-weighted imaging and MR spectroscopy

BACKGROUND

Recently carcinosarcoma has become regarded as a subset of endometrial carcinoma. Because the clinical course of carcinosarcoma is aggressive with poor prognosis, it should be differentiated from endometrial carcinomas for the appropriate surgical management and adjuvant therapy.

PURPOSE

To clarify the magnetic resonance imaging (MRI) characteristics of uterine carcinosarcoma including diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurement and MR spectroscopy (MRS) with quantitative metabolite evaluation.

MATERIAL AND METHODS

MRI findings of 12 pathologically diagnosed uterine carcinosarcomas obtained on 3T MRI were retrospectively evaluated. The mean and minimum ADCs, and the lipid and choline concentration levels were compared with those of pathologically diagnosed 38 endometrial carcinomas.

RESULTS

The mean and minimum ADCs in carcinosarcomas and endometrial carcinomas were not significantly different. The mean ADC of carcinosarcomas was significantly higher than that of higher grade (G2 and G3) endometrial carcinomas. The choline concentration in carcinosarcomas was significantly lower than that in endometrial carcinomas. High lipid peak was observed in 91% of carcinosarcomas and in 24% of endometrial carcinomas.

CONCLUSION

Large, exophytic heterogeneous endometrial mass containing strongly enhanced areas, which may exhibit "tumor delivery", is a suggestive of carcinosarcoma. Relatively high mean ADC and low choline concentration considering its highly malignant nature due to intra-tumoral heterogeneity with necrosis and epithelial cystic components, and the presence of necrosis-associated high lipid peak may be compatible with carcinosarcoma.

Role of 3T multiparametric-MRI with BOLD hypoxia imaging for diagnosis and post therapy response evaluation of postoperative recurrent cervical cancers

•

In operated cervix cancer, the accuracy of diagnosing vaginal vault/local recurrent lesions was higher at combined multiparametric MR imaging and conventional MR imaging (100%) than at conventional MR imaging (70%) or multiparametric MR imaging (96.7%) alone.

•

We found a significant correlation between percentage tumor regression and pre-treatment parameters: NEI (p = 0.02), the maximum slope (p = 0.04), mADC value (p = 0.001) and amount of hypoxic fraction present in the pretherapy MRI (p = 0.01).

•

Multiparametric and BOLD hypoxia MR Imaging are feasible and reliable in diagnosing post-operative recurrence in cervical cancer and should be applied when there is clinical suspicion of post-operative recurrence.

•

Quantitative image features obtained at multiparametric-MRI with BOLD hypoxia imaging has potential to be an appropriate and reliable biologic target for radiation dose painting to optimize therapy in future.

Objectives

To assess the diagnostic value of multiparametric-MRI (MPMRI) with hypoxia imaging as a functional marker for characterizing and detecting vaginal vault/local recurrence following primary surgery for cervical cancer.

Methods

With institutional review board approval and written informed consent 30 women (median age: 45 years) from October 2009 to March 2010 with previous operated carcinoma cervix and suspected clinical vaginal vault/local recurrence were examined with 3.0T-MRI. MRI imaging included conventional and MPMRI sequences [dynamic contrast enhanced (DCE), diffusion weighted (DW), 1H-MR spectroscopy (1HMRS), blood oxygen level dependent hypoxia imaging (BOLD)]. Two radiologists, blinded to pathologic findings, independently assessed the pretherapy MRI findings and then correlated it with histopathology findings. Sensitivity, specificity, positive predictive value, negative predictive value and their confidence intervals were calculated. The pre and post therapy conventional and MPMRI parameters were analyzed and correlated with response to therapy.

Results

Of the 30 patients, there were 24 recurrent tumors and 6 benign lesions. The accuracy of diagnosing recurrent vault lesions was highest at combined MPMRI and conventional MRI (100%) than at conventional-MRI (70%) or MPMRI (96.7%) alone. Significant correlation was seen between percentage tumor regression and pre-treatment parameters such as negative enhancement integral (NEI) (p = 0.02), the maximum slope (p = 0.04), mADC value (p = 0.001) and amount of hypoxic fraction on the pretherapy MRI (p = 0.01).

Conclusion

Conventional-MR with MPMRI significantly increases the diagnostic accuracy for suspected vaginal vault/local recurrence. Post therapy serial MPMRI with hypoxia imaging follow-up objectively documents the response. MPMRI and BOLD hypoxia imaging provide information regarding tumor biology at the molecular, subcellular, cellular and tissue levels and this information may be used as an appropriate and reliable biologic target for radiation dose painting to optimize therapy in future.

Can the signal-to-noise ratio of choline in magnetic resonance spectroscopy reflect the aggressiveness of endometrial cancer?

RATIONALE AND OBJECTIVES

To differentiate endometrial cancer (ECa) from benign lesions in endometrial or in submucosa (BLs-ESm), and investigate whether the signal-to-noise ratio (SNR) of choline-containing compounds (Cho) obtained from three-dimensional (1)H magnetic resonance spectroscopy (MRS) is associated with the aggressiveness of ECa.

MATERIALS AND METHODS

Thirty-three patients with ECa and 15 patients with BLs-ESm underwent preoperative multivoxel (1)H MRS at 3 T MR. The amplitude of Cho peak of each voxel was recorded, and the corresponding SNR of Cho peak (ChoSNR) was calculated. The maximum ChoSNR (max ChoSNR) for each lesion was identified. The max ChoSNR of ECa and BLs-ESm, as well as type I ECa and type II ECa, was compared. The relationship between max ChoSNR and pathologic characteristics of tumors, including tumor grade, stage, type, and tumor size, was analyzed.

RESULTS

The mean max ChoSNR (±standard deviation [SD]) was 30.93 ± 16.89 for ECa and 10.40 ± 3.07 for BLs-ESm (P < .001). The mean max ChoSNR for type II ECa (48.54 ± 21.46) was higher than that for type I ECa (26.19 ± 12.02, P = .001). There were no significant differences among different grades (P = .449). The Spearman coefficient between max ChoSNR and stage was 0.423 (P = .014); the difference existed only between Ia and III ECa (P = .048). The Pearson coefficient between ChoSNR and tumor size was 0.515 (P = .002).

CONCLUSIONS

The max ChoSNR obtained from MRS can differentiate ECa from BLs and type I ECa and type II ECa, but cannot differentiate between each grade ECa and each International Federation of Gynecology and Obstetrics stage ECa. However, max ChoSNR increased with the increase in International Federation of Gynecology and Obstetrics stage and size of ECa.

Single-shot single-voxel lactate measurements using FOCI-LASER and a multiple-quantum filter

Measurement of tissue lactate using (1) H MRS is often confounded by overlap with intense lipid signals at 1.3 ppm. Single-voxel localization using PRESS is also compromised by the large chemical shift displacement between voxels for the 4.1 ppm (-CH) resonance and the 1.3 ppm -CH3 resonance, leading to subvoxels with signals of opposite phase and hence partial signal cancellation. To reduce the chemical shift displacement to negligible proportions, a modified semi-LASER sequence was written ("FOCI-LASER", abbreviated as fLASER) using FOCI pulses to permit high RF bandwidth even with the limited RF amplitude characteristic of clinical MRI scanners. A further modification, MQF-fLASER, includes a selective multiple-quantum filter to detect lactate and reject lipid signals. The sequences were implemented on a Philips 3 T Achieva TX system. In a solution of brain metabolites fLASER lactate signals were 2.7 times those of PRESS. MQF-fLASER lactate was 47% of fLASER (the theoretical maximum is 50%) but still larger than PRESS lactate. In oil, the main 1.3 ppm lipid peak was suppressed to less than 1%. Enhanced suppression was possible using increased gradient durations. The minimum detectable lactate concentration was approximately 0.5 mM. Coherence selection gradients needed to be at the magic angle to avoid large water signals derived from intermolecular multiple-quantum coherences. In pilot patient measurements, lactate peaks were often observed in brain tumours, but not in cervix tumours; lipids were effectively suppressed. In summary, compared with PRESS, the fLASER sequence yields greatly superior sensitivity for direct detection of lactate (and equivalent sensitivity for other metabolites), while the single-voxel single-shot MQF-fLASER sequence surpasses PRESS for lactate detection while eliminating substantial signals from lipids. This sequence will increase the potential for in vivo lactate measurement as a biomarker in targeted anti-cancer treatments as well as in measurements of tissue hypoxia.

Current opportunities and challenges of magnetic resonance spectroscopy, positron emission tomography, and mass spectrometry imaging for mapping cancer metabolism in vivo

Cancer is known to have unique metabolic features such as Warburg effect. Current cancer therapy has moved forward from cytotoxic treatment to personalized, targeted therapies, with some that could lead to specific metabolic changes, potentially monitored by imaging methods. In this paper we addressed the important aspects to study cancer metabolism by using image techniques, focusing on opportunities and challenges of magnetic resonance spectroscopy (MRS), dynamic nuclear polarization (DNP)-MRS, positron emission tomography (PET), and mass spectrometry imaging (MSI) for mapping cancer metabolism. Finally, we highlighted the future possibilities of an integrated in vivo PET/MR imaging systems, together with an in situ MSI tissue analytical platform, may become the ultimate technologies for unraveling and understanding the molecular complexities in some aspects of cancer metabolism. Such comprehensive imaging investigations might provide information on pharmacometabolomics, biomarker discovery, and disease diagnosis, prognosis, and treatment response monitoring for clinical medicine.

Characterisation of mobile lipid resonances in tissue biopsies from patients with cervical cancer and correlation with cytoplasmic lipid droplets

The aims of this study were to characterise the major saturated and unsaturated lipid peaks in histologically normal cervical epithelium and stroma, dysplastic epithelium (low-grade cervical intraepithelial neoplasia, CIN) and cancer-containing tissue samples from patients with cervical cancer using diffusion-weighted (1) H high-resolution magic angle spinning MRS, to determine whether mobile lipid resonances (MLRs) distinguish tissue types and to test for a correlation between MLRs and the number of cytoplasmic lipid droplets. Diffusion-weighted spectra of tissue biopsies were acquired using a stimulated echo sequence with bipolar gradients. Major saturated and unsaturated MLRs were identified and multivariate analysis of peak combinations was used to determine the best separation between tissue classes. Lipid droplets were visualised with Nile red staining and fluorescence microscopy. Correlations of saturated lipid resonances (0.9 and 1.3 ppm), polyunsaturated resonances (2.8 ppm), triglycerides (4.3 ppm) and unsaturated resonances (5.3 ppm) with average droplet number (per image) were investigated using a Spearman rank test. A large heterogeneity in lipid content among samples was observed, resulting in no significant differences in MLR intensities of individual peaks between the three tissue classes. Linear discriminant analysis separated 'no cancer' from 'cancer' based on the intensities at 0.9, 1.3, 2.2 and 2.8 ppm [area under the curve (AUC) = 0.939, p < 0.001], 'low-grade CIN' from 'cancer' based on the intensities at 0.9, 4.1, 4.3 and 5.3 ppm (AUC = 0.987, p < 0.001) and 'no cancer' from 'low-grade CIN' based on intensities at 0.9, 2.2 and 4.3 ppm (AUC = 0.984, p < 0.001). The distribution of cytoplasmic lipid droplets was nonuniform and was not related to the presence of epithelial or stromal components. On average, there were more droplets visible in low-grade CIN and cancer-containing tissues. Significant correlations between MLR peaks and lipid droplet number were seen for 0.9 (p = 0.002), 1.3 (p = 0.003) and 2.8 ppm (p = 0.018). MLR combinations indicative of average lipid structure efficiently separated tissue classes. Increased lipid resonances correlated with increased numbers of cytoplasmic lipid droplets.

MR-visible lipids and the tumor microenvironment

MR-visible lipids or mobile lipids are defined as lipids that are observable using proton MRS in cells and tissues. These MR-visible lipids are composed of triglycerides and cholesterol esters that accumulate in neutral lipid droplets, where their MR visibility is conferred as a result of the increased molecular motion available in this unique physical environment. This review discusses the factors that lead to the biogenesis of MR-visible lipids in cancer cells and in other cell types, such as immune cells and fibroblasts. We focus on the accumulations of mobile lipids that are inducible in cultured cells by a number of stresses, including culture conditions, and in response to activating stimuli or apoptotic cell death induced by anticancer drugs. This is compared with animal tumor models, where increases in mobile lipids are observed in response to chemo- and radiotherapy, and to human tumors, where mobile lipids are observed predominantly in high-grade brain tumors and in regions of necrosis. Conducive conditions for mobile lipid formation in the tumor microenvironment are discussed, including low pH, oxygen availability and the presence of inflammatory cells. It is concluded that MR-visible lipids appear in cancer cells and human tumors as a stress response. Mobile lipids stored as neutral lipid droplets may play a role in the detoxification of the cell or act as an alternative energy source, especially in cancer cells, which often grow in ischemic/hypoxic environments. The role of MR-visible lipids in cancer diagnosis and the assessment of the treatment response in both animal models of cancer and human brain tumors is also discussed. Although technical limitations exist in the accurate detection of intratumoral mobile lipids, early increases in mobile lipids after therapeutic interventions may be useful as a potential biomarker for the assessment of treatment response in cancer.

Molecular imaging of cancer: MR spectroscopy and beyond

Proton magnetic resonance spectroscopic imaging is a non-invasive diagnostic tool for the investigation of cancer metabolism. As an adjunct to morphologic and dynamic magnetic resonance imaging, it is routinely used for the staging, assessment of treatment response, and therapy monitoring in brain, breast, and prostate cancer. Recently, its application was extended to other cancerous diseases, such as malignant soft-tissue tumours, gastrointestinal and gynecological cancers, as well as nodal metastasis. In this review, we discuss the current and evolving clinical applications of proton magnetic resonance spectroscopic imaging. In addition, we will briefly discuss other evolving techniques, such as phosphorus magnetic resonance spectroscopic imaging, sodium imaging and diffusion-weighted imaging in cancer assessment.

Quantification of metabolites in breast cancer patients with different clinical prognosis using HR MAS MR spectroscopy

Absolute quantitative measures of breast cancer tissue metabolites can increase our understanding of biological processes. Electronic REference To access In vivo Concentrations (ERETIC) was applied to high resolution magic angle spinning MR spectroscopy (HR MAS MRS) to quantify metabolites in intact breast cancer samples. The ERETIC signal was calibrated using solutions of creatine and TSP. The largest relative errors of the ERETIC method were 8.4%, compared to 4.4% for the HR MAS MRS method using TSP as a standard. The same MR experimental procedure was applied to intact tissue samples from breast cancer patients with clinically defined good (n = 13) and poor (n = 16) prognosis. All samples were examined by histopathology for relative content of different tissue types and proliferation index (MIB-1) after MR analysis. The resulting spectra were analyzed by quantification of tissue metabolites (β-glucose, lactate, glycine, myo-inositol, taurine, glycerophosphocholine, phosphocholine, choline and creatine), by peak area ratios and by principal component analysis. We found a trend toward lower concentrations of glycine in patients with good prognosis (1.1 µmol/g) compared to patients with poor prognosis (1.9 µmol/g, p = 0.067). Tissue metabolite concentrations (except for β-glucose) were also found to correlate to the fraction of tumor, connective, fat or glandular tissue by Pearson correlation analysis. Tissue concentrations of β-glucose correlated to proliferation index (MIB-1) with a negative correlation factor (-0.45, p = 0.015), consistent with increased energy demand in proliferating tumor cells. By analyzing several metabolites simultaneously, either in ratios or by metabolic profiles analyzed by PCA, we found that tissue metabolites correlate to patients' prognoses and health status five years after surgery. This study shows that the diagnostic and prognostic potential in MR metabolite analysis of breast cancer tissue is greater when combining multiple metabolites (MR Metabolomics).

Detection of cancer in cervical tissue biopsies using mobile lipid resonances measured with diffusion-weighted (1)H magnetic resonance spectroscopy

The purpose of this study was to implement a diffusion-weighted sequence for visualisation of mobile lipid resonances (MLR) using high resolution magic angle spinning (HR-MAS) (1)H MRS and to evaluate its use in establishing differences between tissues from patients with cervical carcinoma that contain cancer from those that do not. A stimulated echo sequence with bipolar gradients was modified to allow T(1) and T(2) measurements and optimised by recording signal loss in HR-MAS spectra as a function of gradient strength in model lipids and tissues. Diffusion coefficients, T(1) and apparent T(2) relaxation times were measured in model lipid systems. MLR profiles were characterised in relation to T(1) and apparent T(2) relaxation in human cervical cancer tissue samples. Diffusion-weighted (DW) spectra of cervical biopsies were quantified and peak areas analysed using linear discriminant analysis (LDA). The optimised sequence reduced spectral overlap by suppressing signals originating from low molecular weight metabolites and non-lipid contributions. Significantly improved MLR visualisation allowed visualisation of peaks at 0.9, 1.3, 1.6, 2.0, 2.3, 2.8, 4.3 and 5.3 ppm. MLR analysis of DW spectra showed at least six peaks arising from saturated and unsaturated lipids and those arising from triglycerides. Significant differences in samples containing histologically confirmed cancer were seen for peaks at 0.9 (p < 0.006), 1.3 (p < 0.04), 2.0 (p < 0.03), 2.8 (p < 0.003) and 4.3 ppm (p < 0.0002). LDA analysis of MLR peaks from DW spectra almost completely separated two clusters of cervical biopsies (cancer, 'no-cancer'), reflecting underlying differences in MLR composition. Generated Receiver Operating Characteristic (ROC) curves and calculated area under the curve (0.962) validated high sensitivity and specificity of the technique. Diffusion-weighting of HR-MAS spectroscopic sequences is a useful method for characterising MLR in cancer tissues and displays an accumulation of lipids arising during tumourigenesis and an increase in the unsaturated lipid and triglyceride peaks with respect to saturated MLR.

Phenotyping murine models of non-alcoholic fatty liver disease through metabolic profiling of intact liver tissue

NAFLD (non-alcoholic fatty liver disease) is a common cause of chronic liver disease associated with the metabolic syndrome. Effective techniques are needed to investigate the potential of animal models of NAFLD. The present study aimed to characterize murine models of NAFLD by metabolic profiling of intact liver tissue. Mice of three strains (BALB/c, C3H and the novel mutant, Gena/263) were fed a control or high-fat diet. Biometric, biochemical and histological analysis demonstrated a spectrum of NAFLD from normal liver to steatohepatitis. Metabolic profiling of intact liver tissue, using 1H MAS (proton magic angle spinning) MRS (magnetic resonance spectroscopy), showed an increase in the total lipid-to-water ratio, a decrease in polyunsaturation indices and a decrease in total choline with increasing disease severity. Principal components analysis and partial least-squares discriminant analysis showed separation of each model from its control and of each model from the total dataset. Class membership from the whole dataset was predicted with 100% accuracy in six out of eight models. Those models with steatosis discriminated from those with steatohepatitis with 100% accuracy. The separation of histologically defined steatohepatitis from simple steatosis is clinically important. Indices derived from 1H MAS MRS studies may inform subsequent in vivo MRS studies at lower field strengths.

Targeting regions with highest lipid content on MR spectroscopy may improve diagnostic yield in stereotactic biopsy

Gliomas are heterogeneous brain tumors and prognosis and treatment are dependent on the highest histological grade present. Stereotactic biopsy is associated with an inherent risk of sampling error. Magnetic resonance spectroscopy (MRS) uses clinical MR scanners to provide chemical in addition to conventional information. MRS studies in brain tumors have found increased levels of choline-containing compounds (Cho) and decreased levels of N-acetylaspartate (NAA), creatine (Cr) and phosphocreatine (PCr) which are all associated with increased grade of glioma. We propose the use of MRS-guided stereotactic biopsy of astrocytomas to increase diagnostic yield and reduce the sampling error rate. MRS was performed on two patients undergoing stereotactic biopsy for suspected astrocytoma. Spectral peak heights of the metabolites Cho at 3.2 parts per million (ppm) chemical shift, NAA at 2.0 ppm and lipid (Lip) at 1.2 ppm, were measured. Biopsy targets were selected from the voxels with the highest Cho/NAA and normalised against Cho levels in the contralateral normal tissue, as well as those with highest lipid content. The biopsies were taken and tissue diagnosis was obtained via standard histological techniques. Histological grade was found to be different in one case: the region with a high Lip/Cr and Cho/NAA ratios showed glioblastoma, whereas the region with high Cho/NAA but low Lip/Cr ratios showed anaplastic astrocytoma. The second patient had high Cho/NAA ratio but low Lip/Cr ratio in both targets and the histology revealed anaplastic astrocytoma in both samples. MRS is a useful biomedical imaging tool for diagnosing and grading astrocytomas. Targeting regions with highest lipid content can potentially improve the diagnostic yield and minimize sampling error in stereotactic biopsy.

Using metabolomics to monitor anticancer drugs

The metabolome of a cancer cell is likely to show changes after responding to an anticancer drug. These changes could be used to decide whether to continue treatment or, in the context of a drug trial, to indicate whether the drug is working and perhaps its mechanism of action. (Nuclear) magnetic resonance spectroscopy (NMR/MRS) methods can offer important insights into novel anticancer agents in order to accelerate the drug development process including time-course studies on the effect of a drug on its site of action (termed pharmacodynamics), in this case the cancer. In addition, some classes of anticancer agents currently under development (e.g. antiangiogenics) are designed to be used in combination with other drugs and will not cause tumour shrinkage when used as single agents in Phase 1 clinical trials. Thus NMR/MRS may have a special role in monitoring the pharmacodynamic actions of such drugs in early-phase clinical trials. This review focuses on the use of ex vivo NMR and in vivo MRS methods for monitoring the effect of some novel anticancer drugs on the cancer metabolome. Ex vivo NMR methods are complementary to in vivo measurements, as they can provide additional information and help in the interpretation of the in vivo data.

Proton spectroscopy provides accurate pathology on biopsy and in vivo

In the last 25 years, MR spectroscopy (MRS) has moved from being a basic research tool into routine clinical use. The spectroscopy method reports on those chemicals that are mobile on the MR time scale. Many of these chemicals reflect specific pathological processes but are complicated by the fact that many chemicals change at one time. There are currently two clinical applications for spectroscopy. The first is in the pathology laboratory, where it can be an adjunct to, and in some cases replacement, for difficult pathologies like Barrett's esophagus and follicular adenoma of the thyroid. The spectroscopy method on a breast biopsy can also report on prognostic indicators, including the potential for spread, from information present in the primary tumor alone. The second application for spectroscopy is in vivo to provide a preoperative diagnosis and this is now achievable for several organs including the prostate. The development of spectroscopy for clinical purposes has relied heavily on the serially-sectioned histopathology to confirm the high accuracy of the method. The combination of in vivo MRI, in vivo MRS, and ex vivo MRS on biopsy samples offers a modality of very high accuracy for preoperative diagnosis and provision of prognostic information for human cancers.

In vivo detection of metabolic changes by 1H-MRS in the DEN-induced hepatocellular carcinoma in Wistar rat

PURPOSE

To investigate the serial changes of the hepatic metabolites in a chemical-induced rat model of hepatocellular carcinoma (HCC) in vivo by a clinical 1.5 T MR scanner.

METHODS

Diethyl nitrosamine (DEN) induced HCC model rats (n=60) and control rats (n=20) were included. From week 7 to week 20 after DEN administration, every other week 10-12 animals (8-9 treated and 2-3 controls) were randomly scanned before being sacrificed. According to the pathologic changes, the whole process of tumorigenesis was divided into early and late periods (week 7-13 and week 14-20, respectively). The serial hepatic changes were tested by both routine MRI and single voxel 1H-MRS and compared with pathological results. Point resolved spectroscopy sequence (PRESS) was used for the location in MRS. The integrations of lipid- and choline-containing metabolites were calculated and analyzed.

RESULTS

All of the listed tests were fully finished in 66 rats (48 treated and 18 controls). Of the MRS curves, 65.2% (43/66) could be analyzed (mainly with resistant baseline with peaks appearing at right positions). From those qualified MRS curves, there were up to seven peaks which could be identified. The peaks of methylene lipids and methyl lipids were combined together in most cases and became the most notable component. The relative integrals of the combined lipid peak and that of the choline-containing compounds in different groups and stages were measured. Comparing with that of the controls of the same stage, the lipid of treated rats decreased in the late stage, and the choline-containing compounds increased in the same stage. Statistically significant differences were found (P<0.05) for the integrals of the lipid and the choline-containing metabolites between treated and controls in the late stage.

CONCLUSIONS

Our initial studies for the integrals of the lipid compounds and the choline-containing metabolites might be useful for a better understanding of the metabolic activity of this DEN-induced rat HCC model.

Magnetic resonance in surgical oncology: II - literature review

Ex vivo and in vivo applications of magnetic resonance spectroscopy have been developed which aid in distinguishing malignant from normal tissues. Studies of breast, colon, cervix, oesophageal and prostate cancer reveal both the successes and failings of present technology. Verification that these non-invasive tests might supplant conventional histology in obtaining spatial diagnostic and chemical prognostic information remains for the time being illusive.

Synchronous endometrial and cervical tumors in a 26-year-old nullipara: diagnostic modalities updated

Proton magnetic resonance spectroscopy (MRS), performed on conventional magnetic resonance imaging (MRI) scanners, provides useful information at the biochemical level. MRS has been used to measure tissue concentrations of proton-containing compounds such as organic and amino acids, and sugars in living tissues. We have used MRS in a 26-year-old female with suspected cervical and endometrial carcinomas. With the use of the above mentioned technique, biochemical differences in the endometrium and the cervix tissues were detected. The presented case is the first virgin patient in the relevant literature in whom endometrial and cervical carcinoma was detected. Choline (Cho), creatine (Cr), N-acetylaspartate (NAA), lipid and lactate region of the MRS spectrum suggested that the technique could be used as an indicator of metabolic alterations in the cervical and endometrial tumor cells.

Magnetic resonance spectroscopy of premalignant and malignant endometrial disorders: a feasibility of in vivo study

OBJECTIVE

To assess the potential clinical utility of in vivo proton magnetic resonance spectroscopy (MRS) in patients with various endometrial lesions.

METHODS

Twelve patients with untreated uterine bleeding were included in this study. In-vivo proton MRS was performed using a 1.5 T MR scanner. The metabolite levels were classified into three classes in comparison with the noise level by visual examination. All the patients have endometrial biopsy. For each type of lesions, chemical compound were described.

RESULTS

Pathological examination resulted in three endometrial cancer, two simple hyperplasias, one complex hyperplasia, two partial hydatiform mole, two proliferative endometrium and two secretory endometrium. In women with endometrial carcinoma, high choline and lipid signals were detected, whereas no creatine and no lactate signals were found. In women with endometrial hyperplasia, choline signal was detectable in all cases but one case showed lactate signal in addition to choline. In women with partial hydatidiform mole, the only detectable signal was choline. Lipid signals were detected in none of the cases with endometrial hyperplasia and partial hidatidiform mole. In women with either secretory or proliferative endometrium, choline and lactate signals were detectable in all cases but one case showed solely choline. Lipid signals were not detected in any of subjects with secretory or proliferative endometrium.

CONCLUSION

The observed difference is the presence of lipid signal only in endometrial carcinoma.