In vivo proton magnetic resonance spectroscopy of large focal hepatic lesions and metabolite change of hepatocellular carcinoma before and after transcatheter arterial chemoembolization using 3.0-T MR scanner

Hepatocellular carcinoma: State of the art diagnostic imaging

Primary liver cancer is the fourth most common malignancy worldwide, with hepatocellular carcinoma (HCC) comprising up to 90% of cases. Imaging is a staple for surveillance and diagnostic criteria for HCC in current guidelines. Because early diagnosis can impact treatment approaches, utilizing new imaging methods and protocols to aid in differentiation and tumor grading provides a unique opportunity to drastically impact patient prognosis. Within this review manuscript, we provide an overview of imaging modalities used to screen and evaluate HCC. We also briefly discuss emerging uses of new imaging techniques that offer the potential for improving current paradigms for HCC characterization, management, and treatment monitoring.

In vivo detection of dysregulated choline metabolism in paclitaxel-resistant ovarian cancers with proton magnetic resonance spectroscopy

Background

Chemoresistance gradually develops during treatment of epithelial ovarian cancer (EOC). Metabolic alterations, especially in vivo easily detectable metabolites in paclitaxel (PTX)-resistant EOC remain unclear.

Methods

Xenograft models of the PTX-sensitive and PTX-resistant EOCs were built. Using a combination of in vivo proton-magnetic resonance spectroscopy (¹H-MRS), metabolomics and proteomics, we investigated the in vivo metabolites and dysregulated metabolic pathways in the PTX-resistant EOC. Furthermore, we analyzed the RNA expression to validate the key enzymes in the dysregulated metabolic pathway.

Results

On in vivo ¹H-MRS, the ratio of (glycerophosphocholine + phosphocholine) to (creatine + phosphocreatine) ((GPC + PC) to (Cr + PCr))(i.e. Cho/Cr) in the PTX-resistant tumors (1.64 [0.69, 4.18]) was significantly higher than that in the PTX-sensitive tumors (0.33 [0.10, 1.13]) (P = 0.04). Forty-five ex vivo metabolites were identified to be significantly different between the PTX-sensitive and PTX-resistant tumors, with the majority involved of lipids and lipid-like molecules. Spearman’s correlation coefficient analysis indicated in vivo and ex vivo metabolic characteristics were highly consistent, exhibiting the highest positive correlation between in vivo GPC + PC and ex vivo GPC (r = 0.885, P < 0.001). These metabolic data suggested that abnormal choline concentrations were the results from the dysregulated glycerophospholipid metabolism, especially choline metabolism. The proteomics data indicated that the expressions of key enzymes glycerophosphocholine phosphodiesterase 1 (GPCPD1) and glycerophosphodiester phosphodiesterase 1 (GDE1) were significantly lower in the PTX-resistant tumors compared to the PTX-sensitive tumors (both P < 0.01). Decreased expressions of GPCPD1 and GDE1 in choline metabolism led to an increased GPC levels in the PTX-resistant EOCs, which was observed as an elevated total choline (tCho) on in vivo ¹H-MRS.

Conclusions

These findings suggested that dysregulated choline metabolism was associated with PTX-resistance in EOCs and the elevated tCho on in vivo ¹H-MRS could be as an indicator for the PTX-resistance in EOCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03292-z.

NMR spectroscopy of a single mammalian early stage embryo

The resolving power, chemical sensitivity and non-invasive nature of NMR have made it an established technique for in vivo studies of large organisms both for research and clinical applications. NMR would clearly be beneficial for analysis of entities at the microscopic scale of about 1 nL (the nanoliter scale), typical of early development of mammalian embryos, microtissues and organoids: the scale where the building blocks of complex organisms could be observed. However, the handling of such small samples (about 100 µm) and sensitivity issues have prevented a widespread adoption of NMR. In this article we show how these limitations can be overcome to obtain NMR spectra of a mammalian embryo in its early stage. To achieve this we employ ultra-compact micro-chip technologies in combination with 3D-printed micro-structures. Such device is packaged for use as plug & play sensor and it shows sufficient sensitivity to resolve NMR signals from individual bovine pre-implantation embryos. The embryos in this study are obtained through In Vitro Fertilization (IVF) techniques, transported cryopreserved to the NMR laboratory, and measured shortly after thawing. In less than 1 h these spherical samples of just 130-190 µm produce distinct spectral peaks, largely originating from lipids contained inside them. We further observe how the spectra vary from one sample to another despite their optical and morphological similarities, suggesting that the method can further develop into a non-invasive embryo assay for selection prior to embryo transfer.

A Preliminary Study on the Diagnostic Efficacy of Proton Magnetic Resonance Spectroscopy at 3.0T in Rabbit With VX2 Liver Tumor

Background:

To investigate the diagnostic efficacy of choline (Cho) value of magnetic resonance spectroscopy (MRS) in rabbit with VX2 liver tumor via comparative and quantitative analysis with the choline compounds concentration measured by enzyme linked immunosorbent assay (ELISA).

Methods:

MRS was performed on normal liver and VX2 tumor. The Cho value of VX2 tumor was compared with that of normal liver. Tissues were harvested for ELISA to detect the concentrations of acetylcholine (ACh), glycophorophosphygholine (GPC) and phosphochorine (PC). The diagnostic performance of Cho value and concentrations of choline compounds were assessed by receiver operating characteristic (ROC) curve and area under ROC curve (AUC). The specificity and sensitivity were discussed by the maximum Youden’s index.

Results:

The concentration of ACh was obviously higher than that of GPC and PC both in VX2 tumor and normal liver (P < 0.01). Furthermore, the concentration differences among ACh, GPC and PG were the third power of 10. Both the ACh concentration and Cho value of MRS in VX2 tumor were significantly higher than those in normal liver (P < 0.01). The AUC of ACh in VX2 tumor was 0.883, when the cutoff value was 7259000, the sensitivity and specificity of the diagnosis of liver cancer were 94.4% and 77.8%, respectively. The AUC of Cho in VX2 tumor was 0.807, when the cutoff value was 28.35, the sensitivity and specificity of the diagnosis of liver cancer were 83.3% and 77.8%, respectively.

Conclusion:

The change of Cho value in MRS between liver cancer and normal liver was consistent with the changes of concentrations of choline compounds measured by ELISA, especially the change of ACh concentration. The diagnostic efficiency of Cho value and that of choline compounds concentration in liver cancer were extremely similar, with the AUC more than 0.8. We conclude that MRS may be applied as an important, non-invasive biomarker for the diagnosis of liver cancer.

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.

1H-NMR metabolomics reveals a multitarget action of Crithmum maritimum ethyl acetate extract in inhibiting hepatocellular carcinoma cell growth

Hepatocellular carcinoma (HCC) is nowadays the sixth cause of tumour-related deceases worldwide, estimated to become the third in Western countries by 2030. New drugs for HCC treatment still have many adverse effects. Several lines of evidence indicate that plant metabolites offer concrete opportunities for developing new therapeutic strategies for many diseases, including cancer. We previously reported that ethyl acetate extract of a spontaneous edible plant harvested in Apulia, Crithmum maritimum, significantly inhibited cell growth in HCC cells. By ¹H-NMR spectroscopy, here we show that Crithmum maritimum ethyl acetate extract counteracts the Warburg effect, by reducing intracellular lactate, inhibits protein anabolism, by decreasing amino acid level, and affects membrane biosynthesis by lowering choline and phosphocholine. Also, we observed an effect on lipid homeostasis, with a reduction in triglycerides, cholesterol, monounsaturated fatty acids (MUFA), and diunsaturated fatty acids (DUFA), and an increase in polyunsaturated fatty acids (PUFA). Taken together, these data demonstrate that Crithmum maritimum-induced cytostasis is exerted through a multi-effect action, targeting key metabolic processes in HCC cells. Overall, our findings highlight the role of Crithmum maritimum as a promising tool for the prevention and the improvement of the therapeutic options for HCC and other types of tumours.

NMR microsystem for label-free characterization of 3D nanoliter microtissues

Performing chemical analysis at the nanoliter (nL) scale is of paramount importance for medicine, drug development, toxicology, and research. Despite the numerous methodologies available, a tool for obtaining chemical information non-invasively is still missing at this scale. Observer effects, sample destruction and complex preparatory procedures remain a necessary compromise. Among non-invasive spectroscopic techniques, one able to provide holistic and highly resolved chemical information in-vivo is nuclear magnetic resonance (NMR). For its renowned informative power and ability to foster discoveries and life-saving applications, efficient NMR at microscopic scales is highly sought after, but so far technical limitations could not match the stringent necessities of microbiology, such as biocompatible handling, ease of use, and high throughput. Here we introduce a novel microsystem, which combines CMOS technology with 3D microfabrication, enabling nL NMR as a platform tool for non-invasive spectroscopy of organoids, 3D cell cultures, and early stage embryos. In this study we show its application to microlivers models simulating non-alcoholic fatty liver disease, demonstrating detection of lipid metabolism dynamics in a time frame of 14 days based on 117 measurements of single 3D human liver microtissues.

Quantification of Functional MR Predicts Early Response in Post-doxorubicin Drug-Eluting Beads Chemoembolization for Hepatocellular Carcinoma

BACKGROUND

The purpose of this study was to assess the value of functional MRI (fMRI) of post-doxorubicin drug-eluting beads transcatheter arterial chemoembolization (DEB-TACE) for hepatocellular carcinoma (HCC) as an early imaging biomarker of response to therapy.

METHODS

This prospective analysis included 21 consecutive patients undergoing fMRI before and after DEB-TACE at a single medical center from January 2013 to December 2014. Functional MRI, including relative changes in apparent diffusion coefficient (ADC) and choline levels measured at hydrogen-1 magnetic resonance spectroscopy (MRS) of treated lesions, was recorded at baseline before DEB-TACE, and at 1, 2, and 4 weeks after DEB-TACE therapy. Assessment of tumor response was based on dynamic contrast-enhanced computer tomography imaging response according to modified response evaluation criteria in solid tumors.

RESULTS

At post-therapy, 76% (n = 16) of patients demonstrated objective tumor response, 10% (n = 2) had stable disease, and 3 (14%) had progressive disease. Stable disease and progressive disease were designated as non-response. At week 2, the mean change in ADC value of responsive tumors was 0.35 ± 0.24 mm²/s, which was greater than that of non-response tumors (mean 0.01 ± 0.13 × 10^-3 mm²/s) (P = 0.006). Significant differences were found in mean choline/water ratio between responsive (7.8 ± 4.9 × 10^-3) and non-responsive (17.2 ± 4.9 × 10^-3) tumors (P = 0.005). Composite scores of choline/water ratio and relative change of ADC showed significantly better diagnostic accuracy in non-responsive tumors than responsive tumors (area under the curve = 1.0; P < 0.001).

CONCLUSIONS

Combined DWI and MRS may be used as an early imaging biomarker of therapy response in HCC patients after chemoembolization therapy.

Quantitative MRI for Assessment of Treatment Outcomes in a Rabbit VX2 Hepatic Tumor Model

Globally, primary and secondary liver cancer is one of the most common cancer types, accounting 8.2% of deaths worldwide in 2018. One of the key strategies to improve the patient's prognosis is the early diagnosis, when liver function is still preserved. In hepatocellular carcinoma (HCC), the typical wash-in/wash-out pattern in conventional magnetic resonance imaging (MRI) reaches a sensitivity of 60% and specificity of 96-100%. However, in recent years functional MRI sequences such as hepatocellular-specific gadolinium-based dynamic-contrast enhanced MRI, diffusion-weighted imaging (DWI), and magnetic resonance spectroscopy (MRS) have been demonstrated to improve the evaluation of treatment success and thus the therapeutic decision-making and the patient's outcome. In the preclinical research setting, the VX2 liver rabbit tumor, which once originated from a virus-induced anaplastic squamous cell carcinoma, has played a longstanding role in experimental interventional oncology. Especially the high tumor vascularity allows assessing the treatment response of locoregional interventions such as radiofrequency ablation (RFA) and transcatheter arterial embolization (TACE). Functional MRI has been used to monitor the tumor growth and viability following interventional treatment. Besides promising results, a comprehensive overview of functional MRI sequences used so far in different treatment setting is lacking, thus lowering the comparability of study results. This review offers a comprehensive overview of study protocols, results, and limitations of quantitative MRI sequences applied to evaluate the treatment outcome of VX2 hepatic tumor models, thus generating a unique basis for future MRI studies and potential translation into the clinical setting. Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2019. J. Magn. Reson. Imaging 2020;52:668-685.

Hepatocellular Carcinoma: State of the Art Imaging and Recent Advances

The incidence of hepatocellular carcinoma (HCC) is increasing, with this trend expected to continue to the year 2030. Hepatocarcinogenesis follows a predictable course, which makes adequate identification and surveillance of at-risk individuals central to a successful outcome. Moreover, imaging is central to this surveillance, and ultimately to diagnosis and management. Many liver study groups throughout Asia, North America and Europe advocate a surveillance program for at-risk individuals to allow early identification of HCC. Ultrasound is the most commonly utilized imaging modality. Many societies offer guidelines on how to diagnose HCC. The Liver Image Reporting and Data System (LIRADS) was introduced to standardize the acquisition, interpretation, reporting and data collection of HCC cases. The LIRADS advocates diagnosis using multiphase computed tomography or magnetic resonance imaging (MRI) imaging. The 2017 version also introduces contrast-enhanced ultrasound as a novel approach to diagnosis. Indeed, imaging techniques have evolved to improve diagnostic accuracy and characterization of HCC lesions. Newer techniques, such as T1 mapping, intravoxel incoherent motion analysis and textural analysis, assess specific characteristics that may help grade the tumor and guide management, allowing for a more personalized approach to patient care. This review aims to analyze the utility of imaging in the surveillance and diagnosis of HCC and to assess novel techniques which may increase the accuracy of imaging and determine optimal treatment strategies.

Levels of choline-containing compounds in normal liver and liver metastases of colorectal cancer as recorded by 1 H MRS

PURPOSE

A relatively high signal for choline-containing compounds (total choline, tCho) is commonly found in ¹ H MR spectra of malignant tumors, but it is unclear if this also occurs in tumors in the liver. We evaluated the potential of the tCho signal in single voxel ¹ H MR spectra of the human liver to assess metastases of colorectal cancers.

EXPERIMENT

MR spectra of an 8 cm³ PRESS-localized voxel were obtained at 3 T from the livers of 12 healthy volunteers and from metastatic lesions in 20 patients in two different sessions. To correct for motion artifacts, sequentially recorded spectra were individually phased and frequency aligned before averaging. Spectra were analyzed using LCModel and tissue levels estimated by water referencing. Repeatability was assessed with Bland-Altman analyses. To estimate tumor necrosis, diffusion-weighted imaging of the liver was performed. High resolution magic angle spinning (HRMAS) spectra of tumor and normal liver samples were obtained at 11.7 T.

RESULTS

With increasing tumor volumes, tCho levels decreased, indicating a partial volume effect. Mean tCho content in tumors larger than the PRESS voxel (>8 cm³ ) was significantly lower (p < 0.01) than for normal liver: 1.6 (range 0.0-3.4) versus 6.9 (range 4.9-11.1) mmol/kg wet weight, while it was comparable for tumors smaller than 8 cm³ : 7.0 (range 3.8-9.3) mmol/kg. The higher 90th percentile apparent diffusion coefficient value in the larger lesions indicates more necrosis. Measurement repeatability was average in normal livers and poor in tumors. HRMAS did not show substantial differences in choline-containing compounds between normal liver and metastasis.

CONCLUSION

An increased tCho content was not observed in ¹ H MR spectra of liver metastasis of colorectal cancer, compared with normal liver. This may be due to the background of a high tCho signal in spectra of normal liver or to an intrinsic lower tCho content in these tumors, but is most likely the result of necrosis in metastatic tumor tissue.

Fully navigated 3 T proton magnetic resonance spectroscopy of liver metastases with inner-volume saturation

PURPOSE

To demonstrate that fully navigated magnetic resonance spectroscopy (MRS) with inner-volume saturation (IVS) at 3 T results in high-quality spectra that permit evaluating metabolic changes in hepatic metastases without the need for patient compliance.

METHODS

Nine patients with untreated, biopsy-proven large hepatic metastases (minimum diameter of 3 cm) were included. In each patient, localized proton MRS was performed in the metastatic lesion and in uninvolved liver parenchyma. To improve quality and consistency of proton MRS, navigator gating was thereby performed not only during acquisition of the spectroscopic data but also during localization imaging and throughout the preparation phases. IVS was utilized to reduce chemical shift displacement between different metabolites and to diminish flow artifacts. Metabolite quantities were normalized relative to the unsuppressed water peak and choline-containing compounds (CCC) to lipid ratios were determined. Wilcoxon signed-rank tests were used to assess differences in the amounts of lipids and CCC as well as the CCC-to-lipid ratios between liver metastases and normal-appearing liver parenchyma.

RESULTS

Fully navigated point-resolved spectroscopy with IVS resulted in high-quality spectra in all patients. Navigator gating during localization imaging and spectroscopic acquisition thereby ensured a precise localization of the spectroscopic voxel. Decreased quantities of lipid and CCC were observed in metastatic tissue compared with uninvolved liver parenchyma. However, the latter trend fell short of statistical significance. Moreover, elevated levels of the CCC-to-lipid ratios were detected in metastatic tissue relative to normal-appearing liver parenchyma.

CONCLUSIONS

The present study demonstrates that fully navigated MRS of the liver with IVS at 3 T allows for a precise localization of the spectroscopic voxel and results in high-quality spectra that permit evaluating liver metabolism without the need for patient compliance.

Multiple breath-hold proton spectroscopy of human liver at 3T: Relaxation times and concentrations of glycogen, choline, and lipids

PURPOSE

To evaluate the feasibility of an expiration multiple breath-hold ¹ H-MRS technique to measure glycogen (Glycg), choline-containing compounds (CCC), and lipid relaxation times T₁ , T₂ , and their concentrations in normal human liver.

MATERIALS AND METHODS

Thirty healthy volunteers were recruited. Experiments were performed at 3T. Multiple expiration breath-hold single-voxel point-resolved spectroscopy (PRESS) technique was used for localization. Water-suppressed spectra were used for the estimation of Glycg, CCC, lipid methylene (CH₂ )_n relaxation times and concentrations. Residual water lines were removed by the Hankel Lanczos singular value decomposition filter. After phase correction and frequency alignment, spectra were averaged and processed by LCModel. Summed signals of Glycg resonances H2H4', H3, and H5 between 3.6 and 4 ppm were used to estimate their apparent relaxation times and concentration. Glycg, CCC, and lipid content were estimated from relaxation corrected spectral intensity ratios to unsuppressed water line.

RESULTS

Relaxation times were measured for liver Glycg (T₁ , 892 ± 126 msec; T₂ , 13 ± 4 msec), CCC (T₁ , 842 ± 75 msec; T₂ , 50 ± 5 msec), lipid (CH₂ )_n (T₁ , 402 ± 19 msec; T₂ , 52 ± 3 msec), and water (T₁ , 990 ± 89 msec; T₂ , 30 ± 2 msec). Mean CCC and lipid concentrations of healthy liver were 7.8 ± 1.3 mM and 15.8 ± 23.6 mM, respectively. Glycg content was found lower in the morning (48 ± 21 mM) compared to the afternoon (145 ± 50 mM).

CONCLUSION

Multiple breath-hold ¹ H-MRS together with dedicated postprocessing is a feasible technique for the quantification of liver Glycg, CCC, and lipid relaxation times and concentrations.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:410-417.

Proton magnetic resonance spectroscopy in oncology: the fingerprints of cancer?

Abnormal metabolism is a key tumor hallmark. Proton magnetic resonance spectroscopy (1H-MRS) allows measurement of metabolite concentration that can be utilized to characterize tumor metabolic changes. 1H-MRS measurements of specific metabolites have been implemented in the clinic. This article performs a systematic review of image acquisition and interpretation of 1H-MRS for cancer evaluation, evaluates its strengths and limitations, and correlates metabolite peaks at 1H-MRS with diagnostic and prognostic parameters of cancer in different tumor types.

Radiological biomarkers for assessing response to locoregional therapies in hepatocellular carcinoma: From morphological to functional imaging (Review)

Many hepatocellular carcinoma (HCC) patients do not qualify for curative surgical intervention and are instead treated with locoregional therapies (LRTs) including ablative and endovascular therapies. Assessment of imaging response is essential in the management of HCC for determining efficacy of therapy and as a surrogate marker for improved survival. The established morphological image biomarkers for tumor burden measurement continue to be applied, as size measurement can easily be used in clinical practice. However, in the setting of liver-directed LRTs for HCC, simple tumor morphological changes can be less informative and usually appear later than biologic changes. Functional imaging (such as perfusion and diffusion imaging, PET-CT/MR and MR spectroscopy) has the potential to be a promising technique for assessment of HCC response to LRTs. Although promising, none of these functional imaging biomarkers have gone through all the required steps of standardization and validation and established accepted criteria for clinical practice.

Application of Single Voxel 1H Magnetic Resonance Spectroscopy in Hepatic Benign and Malignant Lesions

BACKGROUND To quantify the metabolite changes in hepatic tumors by single-voxel 1H magnetic resonance spectroscopy (MRS) at 3.0 T and explore the application value of 1HMRS in the diagnosis of hepatic benign and malignant lesions. MATERIAL AND METHODS A total of 45 patients (55 lesions) diagnosed with hepatic lesions by ultrasound and/or computer topography (CT) from November 2006 to March 2007 were included in this study. All patients underwent 3D-dynamic enhanced scan with liver acquisition with acceleration volume acquisition (LAVA) sequence and single-voxel 1HMRS imaging with PRESS (point-resolved spectroscopy) sequence. The metabolite concentrations such as choline (Cho) and lipids (Lip) were measured. RESULTS There was significant difference regarding the occurrence rate of the obvious elevated Cho peaks between benign and malignant tumors (7/27 vs. 21/28, p=0.000). There was statistical significant differences regarding the Cho/Lip ratios in hepatic benign (0.0686±0.0283, 95% CI: 0.0134-0.1245) and malignant (0.1266 ±0.1124, 95% CI: 0.0937-0.2203) lesions (p<0.05). When compared with the pathological results, the sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were 85.7% (24/28), 92.6% (25/27), 92.3% (24/26), 86.2% (25/29), and 89.1% (49/55) respectively for the MRI assessment, and 92.6% (26/28), 88.9% (24/27), 89.7 (26/29), 92.3 (24/26), and 90.9% (50/55) respectively for 1HMRS combined with MRI assessment. CONCLUSIONS Single Cho peaks or Lip peaks cannot be used for the diagnosis of hepatic benign and malignant lesions. Combined use of 1HMRS and MRI can greatly improve the application value of MRI assessment in the diagnosis of hepatic benign and malignant lesions with a higher sensitivity, negative predictive value, and overall accuracy.

Clinical Imaging of Tumor Metabolism with ¹H Magnetic Resonance Spectroscopy

Magnetic resonance spectroscopy (MRS) is a noninvasive functional technique to evaluate the biochemical behavior of human tissues. This property has been widely used in assessment and therapy monitoring of brain tumors. MRS studies can be implemented outside the brain, with successful and promising results in the evaluation of prostate and breast cancer, although still with limited reproducibility. As a result of technical improvements, malignancies of the musculoskeletal system and abdominopelvic organs can benefit from the molecular information that MRS provides. The technical challenges and main applications in oncology of (1)H MRS in a clinical setting are the focus of this review.

Pediatric Body Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a radiation-free imaging modality with excellent contrast resolution and multiplanar capabilities. Since ionizing radiation is an important concern in the pediatric population, MRI serves as a useful alternative to computed tomography (CT) and also provides additional clues to diagnosis, not discernible on other investigations. Magnetic resonance cholangiopancreatography (MRCP), urography, angiography, enterography, dynamic multiphasic imaging and diffusion-weighted imaging provide wealth of information. The main limitations include, long scan time, need for sedation/anesthesia, cost and lack of widespread availability. With the emergence of newer sequences and variety of contrast agents, MRI has become a robust modality and may serve as a one-stop shop for both anatomical and functional information.

Diagnostic value of 3.0T (1)H MRS with choline-containing compounds ratio (∆CCC) in primary malignant hepatic tumors

Background

The purpose of this study was to investigate the diagnostic value of 3.0-T ¹H magnetic resonance spectroscopy (¹H MRS) in primary malignant hepatic tumors and to compare the effects of ¹H MRS on the diagnostic accuracy of liver-occupying lesions between junior and experienced radiologists.

Methods

This study included 50 healthy volunteers and 40 consecutive patients (50 lesions). Informed consent was obtained from each subject. Images were obtained on clinical whole-body 3.0-T MR system. Point -Resolved Spectroscopy was used to obtain the spectroscopy image. All conventional images were reviewed blindly by junior radiologist and experienced radiologist, respectively. The choline-containing compounds peak area (CCC-A) was measured with SAGE software, and the choline-containing compound ratio (∆CCC) was calculated. The efficacy of CCC-A and ∆CCC in the diagnosis of primary malignant hepatic tumors was determined by plotting receiver operating characteristic (ROC) curves. We also compared the effects of MRS on the diagnostic accuracy of liver-occupying lesions with junior and experienced radiologist.

Results

A significant increase in mean CCC-A was observed in malignant tumors compared with benign tumors. The ROC curve showed ∆CCC had a high discriminatory ability in diagnosing primary malignant hepatic tumors with a sensitivity and specificity of 94.3 and 93.3 %, respectively. The ∆CCC area under the curve (AUC) was 0.97 that was larger than that of both junior and experienced radiologist, while the significantly statistical difference was only obtained between ∆CCC and junior radiologist (P = 0.01).

Conclusion

¹H MRS with ∆CCC demonstrates good efficacy in diagnosing primary malignant hepatic tumors. The technique improves the accuracy of diagnosing liver-occupying lesions, particularly for junior radiologists.

Advanced imaging techniques in the therapeutic response of transarterial chemoembolization for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the major causes of morbidity and mortality in patients with chronic liver disease. Transarterial chemoembolization (TACE) can significantly improve the survival rate of patients with HCC and is the first treatment choice for patients who are not suitable for surgical resections. The evaluation of the response to TACE treatment affects not only the assessment of the therapy efficacy but also the development of the next step in the treatment plan. The use of imaging to examine changes in tumor volume to assess the response of solid tumors to treatment has been controversial. In recent years, the emergence of new imaging technology has made it possible to observe the response of tumors to treatment prior to any morphological changes. In this article, the advances in studies reporting the use of computed tomography perfusion imaging, diffusion-weighted magnetic resonance imaging (MRI), intravoxel incoherent motion, diffusion kurtosis imaging, magnetic resonance spectroscopy, magnetic resonance perfusion-weighted imaging, blood oxygen level-dependent MRI, positron emission tomography (PET)/computed tomography and PET/MRI to assess the TACE treatment response are reviewed.

Multiparametric MR Imaging in Abdominal Malignancies

Modern MR imaging protocols can yield both anatomic and functional information for the assessment of hepatobiliary and pancreatic malignancies. Diffusion-weighted imaging is fully integrated into state-of-the-art protocols for tumor detection, characterization, and therapy monitoring. Hepatobiliary contrast agents have gained ground in the evaluation of focal liver lesions during the last years. Perfusion MR imaging is expected to have a central role for monitoring therapy in body tumors treated with antivascular drugs. Approaches such as Magnetic resonance (MR) elastography and (1)H-MR spectroscopy are still confined to research centers, but with the potential to grow in a short time frame.

1H Magnetic Resonance Spectroscopy Predicts Hepatocellular Carcinoma in a Subset of Patients With Liver Cirrhosis: A Randomized Trial

The goal of this study was to investigate the utility of H magnetic resonance spectroscopy (H-MRS) to quantify the differences in liver metabolites. Magnetic resonance spectroscopy was used as a means of predicting the probability of developing hepatocellular carcinoma (HCC) in patients with liver cirrhosis secondary to chronic hepatitis B.This study included 20 healthy volunteers, 20 patients with liver cirrhosis secondary to chronic hepatitis B (cirrhosis group), and 20 patients with small HCC secondary to cirrhosis liver parenchyma (HCC group). All patients underwent routine MRI and H-MRS scanning. LCModel software was used to quantify Cho (Choline), Lip (lipid), and Cho/Lip in the 3 groups, and a one-way ANOVA was used to compare the differences in these metabolites between groups.Choline levels were significantly different between the control and HCC group and between the cirrhosis group and the HCC group (all P < 0.001). There was also a significant difference in Lip levels between the control and cirrhosis group and the control and HCC groups (all P < 0.001). There were also differences in Cho/Lip between the control and cirrhosis groups, the control and HCC groups, and the cirrhosis and HCC groups (all P < 0.001).H-MRS followed by the analysis with LCModel can be used to measure changes in hepatic metabolite levels in patients with liver cirrhosis secondary to chronic hepatitis B and HCC. Thus, H-MRS may be helpful in monitoring HCC and liver cirrhosis development.

The Value of Proton Magnetic Resonance Spectroscopy in High-Intensity Focused Ultrasound Treatment of Experimental Liver Cancer

High-intensity focused ultrasound (HIFU) is a rapidly developing, non-invasive technique for local treatment of solid tumors that produce coagulative tumor necrosis. This study is aimed to investigate the feasibility of proton magnetic resonance spectroscopy (MRS) on early assessing treatment of HIFU ablation in rabbit with VX2 liver tumor. HIFU ablation was performed on normal liver and VX2 tumor in rabbit, and MRS was performed on normal liver and VX2 tumor before and 2 days after 100% HIFU ablation or 80% ablation in tumor volume. Choline (Cho) and choline/lipid (Cho/Lip) ratios between complete and partial HIFU ablation of tumor were compared. Tissues were harvested and sequentially sliced to confirm the necrosis. In normal liver, the Cho value liver was not obviously changed after HIFU (P > .05), but the Cho/Lip ratio was decreased (P < .05). Cho in liver VX2 tumor was much higher than that in normal liver (P < .001). Cho and Cho/Lip ratio were significantly decreased in tumor after complete HIFU ablation and partial HIFU ablation, and the Cho value in complete HIFU tumor ablation did not show any difference from that in normal liver after HIFU (P > .05); however, the Cho value in partial ablation was still higher than that in normal liver before or in tumor after complete HIFU treatment due to the residual part of tumors, and Cho/Lip ratio is lower than that in complete HIFU treatment (P < .001). The changes in MRS parameters were consistent with histopathologic changes of the tumor tissues after treatment. MRS could differentiate the complete tumor necrosis from residual tumor tissue, when combined with magnetic resonance imaging. We conclude that MRS may be applied as an important, non-invasive biomarker for monitoring the thoroughness of HIFU ablation.

Navigator based respiratory gating during acquisition and preparation phases for proton liver spectroscopy at 3 T

Proton magnetic resonance spectroscopy ((1)H MRS) enables the non-invasive investigation of the human liver; however, because of technical difficulties it is not regularly used for diagnosis of liver diseases in clinical routine. Breathing motion is one of the major challenges, as it decreases spectral quality and leads to misplacement of the spectroscopic voxel. To overcome this problem, real-time navigator gating for spectral acquisition and preparation steps (B0 shimming, water frequency determination, receiver gain optimization, and water suppression) combined with short TE , optimized first order projection based B0 shimming, water suppression, and inner-volume saturated point resolved spectroscopy (PRESS) at 3 T is suggested. Simultaneous lipid and trimethylamine quantification is demonstrated by means of phantom, volunteer, and representative patient measurements. Precise localization of the voxel despite respiratory motion, increased spectral quality (higher signal-to-noise ratio and reduced linewidth) compared with measurements without respiratory gating, and the possibility of acquiring data without additional subject instructions regarding breathing enable robust and accurate liver (1)H MRS measurements with this novel acquisition protocol.

Novel functional magnetic resonance imaging biomarkers for assessing response to therapy in hepatocellular carcinoma

The established and adapted image biomarkers based on size for tumor burden measurement continue to be applied to hepatocellular carcinoma (HCC) as size measurement can easily be used in clinical practice. However, in the setting of novel targeted therapies and liver directed treatments, simple tumor anatomical changes can be less informative and usually appear later than biological changes. Functional magnetic resonance imaging (MRI) has a potential to be a promising technique for assessment of HCC response to therapy. In this review, we discuss various functional MRI biomarkers that play an increasingly important role in evaluation of HCC response after treatment.

Functional imaging biomarkers for assessing response to treatment in liver and lung metastases

Management of patients with metastatic cancer and development of new treatments rely on imaging to provide non-invasive biomarkers of tumour response and progression. The widely used size-based criteria have increasingly become inadequate where early measures of response are required to avoid toxicity of ineffective treatments, as biological, physiologic, and molecular modifications in tumours occur before changes in gross tumour size. A multiparametric approach with the current range of imaging techniques allows functional aspects of tumours to be simultaneously interrogated. Appropriate use of these imaging techniques and their timing in relation to the treatment schedule, particularly in the context of clinical trials, is fundamental. There is a lack of consensus regarding which imaging parameters are most informative for a particular disease site and the best time to image so that, despite an increasing body of literature, open questions on these aspects remain. In addition, standardization of these new parameters is required. This review summarizes the published literature over the last decade on functional and molecular imaging techniques in assessing treatment response in liver and lung metastases.

Proton magnetic resonance spectroscopy: ex vivo study to investigate its prognostic role in colorectal cancer

BACKGROUND

Proton Magnetic Resonance Spectroscopy (1H MRS) is used for clinical diagnosis in some tumours. The aim of this study is to explore ex vivo the potential of 1H MRS in identifying malignancy through metabolic markers in the perspective of its application in all cases of difficult diagnosis and after neoadjuvant treatment.

METHODS

Spectroscopy was performed ex vivo on 29 colorectal specimens. All patients were staged with imaging, underwent radical surgery and then followed-up. Spectral quantification analysis of components expressed in colorectal tumours and in healthy mucosa were evaluated. The MRS-tumour marker (MRS-tm) was calculated for each case. The U-test was used to compare MRS-tm in tumours and in healthy mucosa. In order to select a cut-off for MRS-tm in the tumour and healthy mucosa and to distinguish patients who were disease-free or with recurrence-progression, we performed the ROC curve analysis.

RESULTS

In the 24 subjects without neoadjuvant treatment, it was found that MRS-tm is able to discriminate healthy and neoplastic tissue and can discriminate patients with risk of recurrence/progression

CONCLUSION

Our data seem to show that 1H MRS may be successfully applied in vivo non-invasively to differentiate tumours from healthy mucosa and could also distinguish patients with different prognoses.

3.0 T proton magnetic resonance spectroscopy of the liver: Quantification of choline

AIM: To investigate the normal hepatic magnetic resonance spectroscopy findings choline/lipid2 (Cho/Lip2) associated with age and body mass index (BMI).

METHODS: A total of 58 single-voxel proton spectra of the liver were acquired at 3.0 T using the eight-channel phased array abdominal coil as the receiver coil. Consecutive stacks of breath-hold spectra were acquired using the point resolved spectroscopy technique at a short echo time of 30 ms and a repetition time of 1500 ms. The spectra were processed with the SAGE software package. Areas and heights for metabolite resonance were obtained. Student’s t test for unpaired data was used for comparisons of shimming, Cho/Lip2, and lipid content.

RESULTS: There were significant negative correlations between the Cho/Lip2 peak height ratios and BMI (r = -0.615) and age (r = -0.398) (all P < 0.01). Compared with the high-BMI group, the low-BMI group was younger (39.1 ± 13.0 years vs 47.6 ± 8.5 years, t = -2.954, P = 0.005); had better water suppression (93.4% ± 1.4% vs 85.6% ± 11.6%, t = 2.741, P = 0.014); had higher Cho/Lip2 peak heights ratio (0.2 ± 0.14 vs 0.05 ± 0.04, t = 6.033, P < 0.000); and had lower lipid content (0.03 ± 0.08 vs 0.29 ± 0.31, t = -3.309, P = 0.004). Compared with the older group, the younger group had better shimming effects (17.1 ± 3.6 Hz vs 22.0 ± 6.8 Hz, t = -2.919, P = 0.008); higher Cho/Lip2 peak heights ratios (0.03 ± 0.05 vs 0.09 ± 0.12, t = 2.4, P = 0.020); and lower lipid content (0.05 ± 0.11 vs 0.23 ± 0.32, t = -2.337, P = 0.031). Compared with the low-choline peak group, the high-choline peak group had lower lipid content (0.005 ± 0.002 vs 0.13 ± 0.23, t = -3.796, P < 0.000); lower BMI (19.6 ± 2.4 vs 23.9 ± 3.0, t = -4.410, P < 0.000); and younger age (34.7 ± 10.0 years vs 43.2 ± 12.5 years, t = -2.088, P = 0.041).

CONCLUSION: Lipid accumulation could result from the increased fat in the body depending on age and BMI. Lipid can mask the resonance signal of choline.

Functional imaging of the liver

Anatomical-based imaging is used widely for the evaluation of diffuse and focal liver, including detection, characterization, and therapy response assessment. However, a limitation of anatomical-based imaging is that structural changes may occur relatively late in a disease process. By applying conventional anatomical-imaging methods in a more functional manner, specific pathophysiologic alterations of the liver may be assessed and quantified. There has been an increasing interest in both the clinical and research settings, with the expectation that functional-imaging techniques may help solve common diagnostic dilemmas that conventional imaging alone cannot. This review considers the most common functional magnetic resonance imaging, computed tomography, and ultrasound imaging techniques that may be applied to the liver.

Effects of contrast agent and outer volume saturation bands on water suppression and shimming of hepatic single-volume proton MR spectroscopy at 3.0T

Purpose. To determine whether administration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and whether placement of the outer volume saturation bands significantly affect shimming and water suppression on hepatic MR spectroscopic prescanning. Method. Region of interest (ROI) of 2 cm × 2 cm × 2 cm was carefully positioned in the region of the middle portion of the right hepatic lobe. 32 patients were examined before and after administration of Gd-DTPA with and without outer-volume saturation bands. Linewidths (Full-Width Half-Maximum (FWHM)) and water suppression were obtained. A paired t-test for comparison of means was used. Results. (1) The group with the outer volume saturation bands demonstrated slightly better water suppression effect than the group without outer volume saturation bands before administration. (2) The group with the outer volume saturation bands demonstrated better water suppression effect than the group without outer volume saturation bands after administration. (3) Both shimming and water suppression effectswere decreased on enhanced MR spectroscopic prescanning (all P < 0.05). Conclusions. Placement of the outer volume saturation bands is helpful to improve water suppression both before and after contrast agent administration. Gd-DTPA exerts a slightly adverse effect (a statistically significant but clinically unimportant) on magnetic resonance spectroscopic prescanning at 3T.

Differentiating hepatocellular carcinoma from hepatitis C using metabolite profiling

Hepatocellular carcinoma (HCC) accounts for most liver cancer cases worldwide. Contraction of the hepatitis C virus (HCV) is considered a major risk factor for liver cancer. In order to identify the risk of cancer, metabolic profiling of serum samples from patients with HCC (n=40) and HCV (n=22) was performed by ¹H nuclear magnetic resonance spectroscopy. Multivariate statistical analysis showed a distinct separation of the two patient cohorts, indicating a distinct metabolic difference between HCC and HCV patient groups based on signals from lipids and other individual metabolites. Univariate analysis showed that three metabolites (choline, valine and creatinine) were significantly altered in HCC. A PLS-DA model based on these three metabolites showed a sensitivity of 80%, specificity of 71% and an area under the receiver operating curve of 0.83, outperforming the clinical marker alpha-fetoprotein (AFP). The robustness of the model was tested using Monte-Carlo cross validation (MCCV). This study showed that metabolite profiling could provide an alternative approach for HCC screening in HCV patients, many of whom have high risk for developing liver cancer.

Gender-Specific Normal Levels of Myocardial Metabolites Determined by Localized 1H-Magnetic Resonance Spectroscopy

OBJECTIVE: Gender-specific normal concentrations of myocardial metabolites and the differences that might exist between healthy males and females were measured in vivo using 1H-magnetic resonance spectroscopy (1H-MRS). METHODS: A total of 100 healthy individuals (57 males, 43 females) were studied. Cardiac magnetic resonance imaging and localized 1H-MRS were used to localize the voxels and quantify myocardial metabolite concentrations, respectively, for each gender. RESULTS: A total of 14 participants were excluded because of motion and poor spectra, which meant that 86 participants (46 males, 40 females) were included in the final analysis. Spectral peaks were identified with chemical shifts corresponding to water, choline, creatine and triglyceride. Myocardial choline and creatine levels showed no statistically significant differences between males and females. Females had a significantly lower body mass index and body surface area compared with males, and a significantly higher concentration of myocardial triglycerides. CONCLUSIONS: Myocardial triglyceride concentration was shown to be related to gender, whereas myocardial creatine and choline concentrations were not gender-related.

Quantification of choline concentration following liver cell apoptosis using 1H magnetic resonance spectroscopy

AIM: To evaluate the feasibility of quantifying liver choline concentrations in both normal and apoptotic rabbit livers in vivo, using ¹H magnetic resonance spectroscopy (¹H-MRS).

METHODS: ¹H-MRS was performed in 18 rabbits using a 1.5T GE MR system with an eight-channel head/neck receiving coil. Fifteen rabbits were injected with sodium selenite at a dose of 10 μmol/kg to induce the liver cell apoptosis. Point-resolved spectroscopy sequence-localized spectra were obtained from 10 livers once before and once 24 h after sodium selenite injection in vivo. T1 and T2 relaxation time of water and choline was measured separately in the livers of three healthy rabbits and three selenite-treated rabbits. Hematoxylin and eosin and dUTP-biotin nick end labeling (TUNEL) staining was used to detect and confirm apoptosis. Choline peak areas were measured relative to unsuppressed water using LCModel. Relaxation attenuation was corrected using the average of T1 and T2 relaxation time. The choline concentration was quantified using a formula, which was tested by a phantom with a known concentration.

RESULTS: Apoptosis of hepatic cells was confirmed by TUNEL assay. In phantom experiment, the choline concentration (3.01 mmol/L), measured by ¹H-MRS, was in good agreement with the actual concentration (3 mmol/L). The average T1 and T2 relaxation time of choline was 612 ± 15 ms and 74 ± 4 ms in the control group and 670 ± 27 ms and 78 ± 5 ms in apoptotic livers in vivo, respectively. Choline was quantified in 10 rabbits, once before and once after the injection with sodium selenite. The choline concentration decreased from 14.5 ± 7.57 mmol/L before sodium selenite injection to 10.8 ± 6.58 mmol/L (mean ± SD, n = 10) after treatment (Z = -2.395, P < 0.05, two-sample paired Wilcoxon test).

CONCLUSION: ¹H-MRS can be used to quantify liver choline in vivo using unsuppressed water as an internal reference. Decreased liver choline concentrations are found in sodium selenite-treated rabbits undergoing liver cell apoptosis.

Fast detection of choline-containing metabolites in liver using 2D ¹H-¹⁴N three-bond correlation (HN3BC) spectroscopy

Detection and quantification of total choline-containing metabolites (CCMs) in tissues by magnetic resonance spectroscopy (MRS) has received considerable attention as a biomarker of cancer. Tissue CCMs are mainly choline (Cho), phosphocholine (PCho), and glycerophosphocholine (GPCho). Because the methyl (1)H resonances of tissue CCMs exhibit small chemical shift differences and overlap significantly in 1D (1)H MRS, quantification of individual components is precluded. Development of a MRS method capably of resolving individual components of tissue CCMs would be a significant advance. Herein, a modification of the 2D (1)H-(14)N HSQC technique is targeted on the two methylene (1)H in the CH(2)O group ((3)J(1H14N)=2.7 Hz) and applied to ex vivo mouse and human liver samples at physiological temperature (37°C). Specifically, the (1)H-(14)N HSQC technique is modified into a 2D (1)H-(14)N three-bond correlation (HN3BC) experiment, which selectively detects the (1)H of CH(2)O coupled to (14)N in CCMs. Separate signals from Cho, PCho, and GPCho components are resolved with high detection sensitivity. A 2D HN3BC spectrum can be recorded from mouse liver in only 1.5 min and from human carcinoma liver tissue in less than 3 min with effective sample volume of 0.2 ml at 14.1T.

In vivo magnetic resonance spectroscopy of liver tumors and metastases

Primary liver cancer is the fifth most common malignancy in men and the eighth in women worldwide. The liver is also the second most common site for metastatic spread of cancer. To assist in the diagnosis of these liver lesions non-invasive advanced imaging techniques are desirable. Magnetic resonance (MR) is commonly used to identify anatomical lesions, but it is a very versatile technique and also can provide specific information on tumor pathophysiology and metabolism, in particular with the application of MR spectroscopy (MRS). This may include data on the type, grade and stage of tumors, and thus assist in further management of the disease. The purpose of this review is to summarize and discuss the available literature on proton, phosphorus and carbon-13-MRS as performed on primary liver tumors and metastases, with human applications as the main perspective. Upcoming MRS approaches with potential applications to liver tumors are also included. Since knowledge of some technical background is indispensable to understand the results, a basic introduction of MRS and some technical issues of MRS as applied to tumors and metastases in the liver are described as well. In vivo MR spectroscopy of tumors in a metabolically active organ such as the liver has been demonstrated to provide important information on tumor metabolism, but it also is challenging as compared to applications on some other tissues, in particular in humans, mostly because of its abdominal location where movement may be a disturbing factor.

The metabolic features of normal pancreas and pancreatic adenocarcinoma: preliminary result of in vivo proton magnetic resonance spectroscopy at 3.0 T

OBJECTIVE

The objective of the study was to analyze the metabolic features and distribution of normal pancreas and pancreatic adenocarcinoma while determining the biomarker of pancreatic cancerous process.

METHODS

Twenty-seven control and 29 pancreatic adenocarcinoma patients underwent breath-hold 3-T proton magnetic resonance spectroscopy. The ratios of lipid (lipid/InW), choline-containing compounds (CCCs/InW), and fatty acids (FAs/InW) to nonsaturated internal water (InW) of the normal pancreas head and body-tail region, with cancerous and noncancerous regions in pancreatic adenocarcinoma, were calculated.

RESULTS

In normal pancreas, there were no statistical difference in the ratios of FAs to InW and lipid to InW of different regions, but CCCs/InW of body-tail area was greater than that of head (7.28 × 10⁻⁴ vs 3.23 × 10⁻⁴). In pancreatic cancer, FAs/InW and lipid/InW between cancerous and noncancerous region were different (3.44 × 10⁻⁴ vs 16.3 × 10⁻⁴ and 7.78 × 10⁻⁴ vs 36.3 × 10⁻⁴, respectively). Choline-containing compounds/InW in cancerous region was smaller than that in noncancerous region of pancreatic head cancer (1.62 × 10⁻⁴ vs 5.69 × 10⁻⁴) but similar to such region in body-tail cancer. Lipid/InW dropped in noncancerous regions (from 0.67 to 0.36), whereas there were no differences in FAs/InW and CCCs/InW between normal pancreas regions and noncancerous regions in pancreatic cancer.

CONCLUSIONS

In normal pancreas, CCCs of body-tail region was greater than that of head. Whereas in pancreatic adenocarcinoma, CCCs, FAs, and lipid were all decreased in cancerous region, lipid in the noncancerous region was also decreased compared with normal pancreas. Lipid may be the potential sensitive biomarker for pancreatic cancer.

Hepatic tumor response evaluation by MRI

Noninvasive evaluation of hepatic tumor response is necessary to improve the survival rate and quality of life of cancer patients. Among radiologic imaging modalities, MRI plays a significant role in the management of patients with hepatic tumor and is crucial for diagnosis, treatment planning and assessment of response or recurrence, because of its high contrast resolution, lack of ionizing radiation and the possibility of performing functional imaging sequences. This review provides an overview of the MRI findings after various treatments in patients with primary and secondary focal liver malignancies. The imaging methods described focus on the recent trends of using MRI techniques as biomarkers for disease. We also describe the appearance of successful and incomplete response for the various forms of treatment, including transcatheter arterial chemoembolization, ablative therapy, systemic chemotherapy and radiation therapy. Dynamic contrast-enhanced MRI is regarded as an established noninvasive method and potential biomarker for tumor detection, as well as for the characterization of the tumor response. Diffusion-weighted MRI, perfusion-weighted MRI and MRS are also promising functional biomarkers to help select patients for various therapies and to assess the response to treatments. However, further validation and standardization should be performed before their widespread use as imaging biomarkers.

Early response of hepatic malignancies to locoregional therapy-value of diffusion-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy

PURPOSE

The objective of our study was to determine the usefulness of the diffusion-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy (H-MRS) of hepatic malignancies for the assessment of response to locoregional treatment.

METHODS

Forty-four patients (29 men; mean age, 58 years) with hepatic malignancies were treated locally. Magnetic resonance imaging examinations obtained before and at 1 and 6 months after transarterial chemoembolization were analyzed retrospectively. Imaging criteria included change in tumor size, percentage of enhancement in the arterial and portal venous phases, diffusion-weighted magnetic resonance imaging apparent diffusion coefficients, and choline concentration by quantitative H-MRS. Response to treatment was grouped according to RECIST (Response Evaluation Criteria in Solid Tumors) and European Association for the Study of the Liver (EASL) criteria based on magnetic resonance imaging at 6 months after treatment. Statistical analysis used paired t test, Fisher exact test, and univariate and multivariate Cox proportional hazards models.

RESULTS

Before treatment, the median tumor diameter was 6 cm; at 6 months after treatment, median tumor diameter was 5.1 cm. According to RECIST and EASL, 66% of the patients achieved partial response, 31% had stable disease, and 3% of the patients showed progressive disease. One month after transarterial chemoembolization, apparent diffusion coefficient increased (P < 0.14), and mean choline concentration of the tumors decreased (P < 0.008).

CONCLUSIONS

Diffusion-weighted imaging and hepatic choline levels by H-MRS could predict response to locoregional therapy.

Serum and urine metabolite profiling reveals potential biomarkers of human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy in the world with high morbidity and mortality rate. Identification of novel biomarkers in HCC remains impeded primarily because of the heterogeneity of the disease in clinical presentations as well as the pathophysiological variations derived from underlying conditions such as cirrhosis and steatohepatitis. The aim of this study is to search for potential metabolite biomarkers of human HCC using serum and urine metabolomics approach. Sera and urine samples were collected from patients with HCC (n = 82), benign liver tumor patients (n = 24), and healthy controls (n = 71). Metabolite profiling was performed by gas chromatography time-of-flight mass spectrometry and ultra performance liquid chromatography-quadrupole time of flight mass spectrometry in conjunction with univariate and multivariate statistical analyses. Forty three serum metabolites and 31 urinary metabolites were identified in HCC patients involving several key metabolic pathways such as bile acids, free fatty acids, glycolysis, urea cycle, and methionine metabolism. Differentially expressed metabolites in HCC subjects, such as bile acids, histidine, and inosine are of great statistical significance and high fold changes, which warrant further validation as potential biomarkers for HCC. However, alterations of several bile acids seem to be affected by the condition of liver cirrhosis and hepatitis. Quantitative measurement and comparison of seven bile acids among benign liver tumor patients with liver cirrhosis and hepatitis, HCC patients with liver cirrhosis and hepatitis, HCC patients without liver cirrhosis and hepatitis, and healthy controls revealed that the abnormal levels of glycochenodeoxycholic acid, glycocholic acid, taurocholic acid, and chenodeoxycholic acid are associated with liver cirrhosis and hepatitis. HCC patients with alpha fetoprotein values lower than 20 ng/ml was successfully differentiated from healthy controls with an accuracy of 100% using a panel of metabolite markers. Our work shows that metabolomic profiling approach is a promising screening tool for the diagnosis and stratification of HCC patients.

Functional magnetic resonance imaging of the liver: parametric assessments beyond morphology

There is growing interest in exploring and using functional imaging techniques to provide additional information on structural alterations in the liver, which often occur late in the disease process. This article presents a summary of the different functional MR imaging techniques currently in use, focusing on dynamic contrast-enhanced MR imaging, diffusion-weighted MR imaging, MR spectroscopy, in- and oppose-phase MR imaging, and T2*-weighted imaging. For each technique, the biologic underpinning for the technique is explained, the clinical applications surveyed, and the challenges for their application enumerated. Developing and less frequently used techniques such as MR elastography, blood oxygenation level dependent imaging, dynamic susceptibility contrast-enhanced MR imaging, and diffusion-tensor imaging are reviewed. The challenges widespread adoption of functional MR imaging and the translation of such techniques to high field strengths are also discussed.

In vivo lipid profiling using proton magnetic resonance spectroscopy in an experimental liver fibrosis model

RATIONALE AND OBJECTIVES

The aim of this study was to characterize early hepatic lipid changes in an experimental model of liver fibrosis using proton ((1)H) magnetic resonance spectroscopy (MRS) at high magnetic field in vivo.

MATERIALS AND METHODS

Liver fibrosis was induced in 12 Sprague-Dawley rats by twice-weekly carbon tetrachloride (CCl(4)) administration up to 4 weeks. Eight normal rats were used as controls. Single-voxel (1)H MRS experiments were performed at 7 Tesla to measure signal integrals of various lipid peaks including -CH(3), (-CH(2)-)(n), -CH(2)-C=C-CH(2)-, =C-CH(2)-C= and -CH=CH- at 0.9, 1.3, 2.0, 2.8, and 5.3 ppm, respectively, and peak from choline-containing compounds (CCC) at 3.2 ppm. Total lipid, total saturated fatty acid, total unsaturated fatty acid, total unsaturated bond, polyunsaturated bond, and CCC indices were quantified.

RESULTS

Significant increases (P < .01) in total lipid and total saturated fatty acid indices were found in animals with CCl(4)-induced fibrosis as compared with normal animals. In addition, total unsaturated bond and polyunsaturated bond indices of animals at 4 weeks after CCl(4) insult were significantly higher than (P < .01 and P < .05, respectively) those of normal animals and animals at 2 weeks following insult; whereas there was only significant increase (P < .01) in total unsaturated fatty acid index in animals with 4-week CCl(4) insult as compared with normal animals.

CONCLUSION

The hepatic lipid changes in CCl(4)-induced experimental fibrosis model were documented in vivo and longitudinally using (1)H MRS at 7 Tesla. The experimental findings suggested that total saturated fatty acid increase contributed mainly to the total lipid increase in animals with CCl(4) insult. This study also demonstrated the potential value of high field MRS to resolve lipid composition and alterations in liver fibrosis.

Detection of hepatocellular carcinoma with PET/CT: a prospective comparison of 18F-fluorocholine and 18F-FDG in patients with cirrhosis or chronic liver disease

This prospective study aimed to compare the diagnostic performance of (18)F-fluorocholine and (18)F-FDG for detecting and staging hepatocellular carcinoma (HCC) in patients with chronic liver disease and suspected liver nodules.

METHODS

Whole-body PET/CT was performed in a random order at 10 min after injection of 4 MBq of (18)F-fluorocholine per kilogram and at 1 h after injection of 5 MBq of (18)F-FDG per kilogram. PET/CT results were read in a masked manner by 2 specialists, and diagnostic performance was assessed from the results of consensus masked reading. Those focal lesions appearing with increased or decreased activity, compared with background, on (18)F-fluorocholine PET/CT were considered positive for malignancy. The standard of truth was determined on a per-site basis using data from a histologic examination and a follow-up period of more than 6 mo; on a per-patient basis, the Barcelona criteria were also accepted as a proof of HCC in 5 patients.

RESULTS

Eighty-one patients were recruited; standard of truth was determined in 59 cases. HCC was diagnosed in 34 patients. Therefore, sensitivity was 88% for (18)F-fluorocholine and 68% for (18)F-FDG (P = 0.07), and in 70 sites, sensitivity was 84% for (18)F-fluorocholine, significantly better than the 67% for (18)F-FDG (P = 0.01). Of the 11 patients with well-differentiated HCC, 6 had a positive result with (18)F-fluorocholine alone, whereas (18)F-FDG was never positive alone; corresponding site-based sensitivity was 94% for (18)F-fluorocholine and 59% for (18)F-FDG (P = 0.001). The detection rate of 18 sites corresponding to other malignancies was 78% for (18)F-fluorocholine and 89% for (18)F-FDG. In nonmalignant sites, (18)F-fluorocholine appeared less specific than (18)F-FDG (62% vs. 91% P < 0.01) because of uptake by focal nodular hyperplasia.

CONCLUSION

(18)F-fluorocholine was significantly more sensitive than (18)F-FDG at detecting HCC, in particular in well-differentiated forms. In contrast, (18)F-FDG appeared somewhat more sensitive at detecting other malignancies and was negative in focal nodular hyperplasia. Thus (18)F-fluorocholine appears to be a useful PET/CT tracer for the detection and surveillance of HCC; however, performing PET/CT with both radiopharmaceuticals seems to be the best option.

MR spectroscopy of the liver: principles and clinical applications

Magnetic resonance (MR) spectroscopy allows the demonstration of relative tissue metabolite concentrations along a two- or three-dimensional spectrum based on the chemical shift phenomenon. An MR spectrum is a plot of the signal intensity and frequency of a chemical or metabolite within a given voxel. At proton MR spectroscopy, the frequency at which a chemical or compound occurs depends on the configuration of the protons within the structure of that chemical. At in vivo proton MR spectroscopy, the frequency location of water is used as the standard of reference to identify a chemical. The frequency shift or location of chemicals relative to that of water allows generation of qualitative and quantitative information about the chemicals that occur within tissues, forming the basis of tissue characterization by MR spectroscopy. MR spectroscopy also may be used to quantify liver fat by measuring lipid peaks and to diagnose malignancy, usually by measuring the choline peak. Interpretation of MR spectroscopic data requires specialized postprocessing software and is subject to technical limitations including low signal-to-noise ratio, masking of metabolite peaks by dominant water and lipid peaks, partial-volume averaging from other tissue within the voxel, and phase and frequency shifts from motion. MR spectroscopy of the liver is an evolving technology with potential for improving the diagnostic accuracy of tissue characterization when spectra are interpreted in conjunction with MR images.

Parametric exploration of the liver by magnetic resonance methods

MRI, as a completely noninvasive technique, can provide quantitative assessment of perfusion, diffusion, viscoelasticity and metabolism, yielding diverse information about liver function. Furthermore, pathological accumulations of iron and lipids can be quantified. Perfusion MRI with various contrast agents is commonly used for the detection and characterization of focal liver disease and the quantification of blood flow parameters. An extended new application is the evaluation of the therapeutic effect of antiangiogenic drugs on liver tumours. Novel, but already widespread, is a histologically validated relaxometry method using five gradient echo sequences for quantifying liver iron content elevation, a measure of inflammation, liver disease and cancer. Because of the high perfusion fraction in the liver, the apparent diffusion coefficients strongly depend on the gradient factors used in diffusion-weighted MRI. While complicating analysis, this offers the opportunity to study perfusion without contrast injection. Another novel method, MR elastography, has already been established as the only technique able to stage fibrosis or diagnose mild disease. Liver fat content is accurately determined with multivoxel MR spectroscopy (MRS) or by faster MRI methods that are, despite their widespread use, prone to systematic error. Focal liver disease characterisation will be of great benefit once multivoxel methods with fat suppression are implemented in proton MRS, in particular on high-field MR systems providing gains in signal-to-noise ratio and spectral resolution.

Pediatric liver tumors--a pictorial review

Hepatic masses constitute about 5-6% of all intra-abdominal masses in children. The majority of liver tumors in children are malignant; these malignant liver tumors constitute the third most common intra-abdominal malignancy in the pediatric age group after Wilms' tumor and neuroblastoma. Only about one third of the liver tumors are benign. A differential diagnosis of liver tumors in children can be obtained based on the age of the child, clinical information (in particular AFP) and imaging characteristics. The purpose of this review is to report typical clinical and imaging characteristics of benign and malignant primary liver tumors in children.