Can we justify not doing liver perfusion imaging in 2013?

Rim Enhancement after Technically Successful Transarterial Chemoembolization in Hepatocellular Carcinoma: A Potential Mimic of Incomplete Embolization or Reactive Hyperemia?

Contrast enhancement at the margins/rim of embolization areas in hepatocellular-carcinoma (HCC) lesions treated with transarterial chemoembolization (TACE) might be an early prognostic indicator for HCC recurrence. The aim of this study was to evaluate the predictive value of rim perfusion for TACE recurrence as determined by perfusion CT (PCT). A total of 52 patients (65.6 ± 9.3 years) underwent PCT directly before, immediately after (within 48 h) and at follow-up (95.3 ± 12.5 days) after TACE. Arterial-liver perfusion (ALP), portal-venous perfusion (PVP) and hepatic-perfusion index (HPI) were evaluated in normal liver parenchyma, and on the embolization rim as well as the tumor bed. A total of 42 lesions were successfully treated, and PCT measurements showed no residually vascularized tumor areas. Embolization was not entirely successful in 10 patients with remaining arterialized focal nodular areas (ALP 34.7 ± 10.1 vs. 4.4 ± 5.3 mL/100 mL/min, p < 0.0001). Perfusion values at the TACE rim were lower in responders compared to normal adjacent liver parenchyma and edges of incompletely embolized tumors (ALP liver 16.3 ± 10.1 mL/100 mL/min, rim responder 8.8 ± 8.7 mL/100 mL/min, rim non-responder 23.4 ± 8.6 mL/100 mL/min, p = 0.005). At follow-up, local tumor relapse was observed in 17/42, and 15/42 showed no recurrence (ALP 39.1 ± 10.1 mL/100 mL/min vs. 10.0 ± 7.4 mL/100 mL/min, p = 0.0008); four patients had de novo disseminated disease and six patients were lost in follow-up. Rim perfusion was lower compared to adjacent recurring HCC and not different between groups. HCC lesions showed no rim perfusion after TACE, neither immediately after nor at follow-up at three months, both for mid-term responders and mid-term relapsing HCCs, indicating that rim enhancement is not a sign of reactive hyperemia and not predictive of early HCC recurrence.

Quantitative magnetic resonance imaging for focal liver lesions: bridging the gap between research and clinical practice

Magnetic resonance imaging (MRI) is highly important for the detection, characterization, and follow-up of focal liver lesions. Several quantitative MRI-based methods have been proposed in addition to qualitative imaging interpretation to improve the diagnostic work-up and prognostics in patients with focal liver lesions. This includes DWI with apparent diffusion coefficient measurements, intravoxel incoherent motion, perfusion imaging, MR elastography, and radiomics. Multiple research studies have reported promising results with quantitative MRI methods in various clinical settings. Nevertheless, applications in everyday clinical practice are limited. This review describes the basic principles of quantitative MRI-based techniques and discusses the main current applications and limitations for the assessment of focal liver lesions.

Spatial Characterization of Tumor Perfusion Properties from 3D DCE-US Perfusion Maps are Early Predictors of Cancer Treatment Response

There is a need for noninvasive repeatable biomarkers to detect early cancer treatment response and spare non-responders unnecessary morbidities and costs. Here, we introduce three-dimensional (3D) dynamic contrast enhanced ultrasound (DCE-US) perfusion map characterization as inexpensive, bedside and longitudinal indicator of tumor perfusion for prediction of vascular changes and therapy response. More specifically, we developed computational tools to generate perfusion maps in 3D of tumor blood flow, and identified repeatable quantitative features to use in machine-learning models to capture subtle multi-parametric perfusion properties, including heterogeneity. Models were developed and trained in mice data and tested in a separate mouse cohort, as well as early validation clinical data consisting of patients receiving therapy for liver metastases. Models had excellent (ROC-AUC > 0.9) prediction of response in pre-clinical data, as well as proof-of-concept clinical data. Significant correlations with histological assessments of tumor vasculature were noted (Spearman R > 0.70) in pre-clinical data. Our approach can identify responders based on early perfusion changes, using perfusion properties correlated to gold-standard vascular properties.

Sliding motion compensated low-rank plus sparse (SMC-LS) reconstruction for high spatiotemporal free-breathing liver 4D DCE-MRI

Liver dynamic contrast-enhanced MRI (DCE-MRI) requires high spatiotemporal resolution and large field of view to clearly visualize all relevant enhancement phases and detect early-stage liver lesions. The low-rank plus sparse (L + S) reconstruction outperforms standard sparsity-only-based reconstruction through separation of low-rank background component (L) and sparse dynamic components (S). However, the L + S decomposition is sensitive to respiratory motion so that image quality is compromised when breathing occurs during long time data acquisition. To enable high quality reconstruction for free-breathing liver 4D DCE-MRI, this paper presents a novel method called SMC-LS, which incorporates Sliding Motion Compensation into the standard L + S reconstruction. The global superior-inferior displacement of the internal abdominal organs is inferred directly from the undersampled raw data and then used to correct the breathing induced sliding motion which is the dominant component of respiratory motion. With sliding motion compensation, the reconstructed temporal frames are roughly registered before applying the standard L + S decomposition. The proposed method has been validated using free-breathing liver 4D MRI phantom data, free-breathing liver 4D DCE-MRI phantom data, and in vivo free breathing liver 4D MRI dataset. Results demonstrated that SMC-LS reconstruction can effectively reduce motion blurring artefacts and preserve both spatial structures and temporal variations at a sub-second temporal frame rate for free-breathing whole-liver 4D DCE-MRI.

Hepatocellular carcinoma treated with sorafenib: Arterial tumor perfusion in dynamic contrast-enhanced CT as early imaging biomarkers for survival

OBJECTIVES

To investigate whether hepatic perfusion CT yields early imaging biomarkers predictive of the prognosis of hepatocellular carcinoma (HCC) patients treated with sorafenib.

METHODS

We evaluated 36 HCC patients who underwent hepatic perfusion CT before- and one week after sorafenib therapy. We measured arterial and portal perfusion in the hepatic tumor and liver parenchyma [(AP)(PP)_tumor], [(AP)(PP)_liver]. The perfusion ratio was calculated by dividing the post- by the pre-sorafenib value. The effect of each value on the overall survival rate was analyzed with the Cox proportional hazards model; statistically significant parameters were subjected to receiver operating characteristic analysis based on median survival after sorafenib administration to determine the overall survival rate with the Kaplan-Meier method.

RESULTS

Pre-AP_tumor was significantly associated with the overall survival rate (hazard ratio (HR) and 95% confidence interval (CI), 0.16 and 0.02-0.84, p=0.03). The AP_tumor ratio tended to be associated with the overall survival rate (HR and 95% CI, 2.94 and 0.94-7.88, p=0.06). The overall survival rate was higher in patients with pre-AP_tumor>71.7mL/min/100mL, and with AP_tumor ratio≦1.1 (p<0.01 and 0.03, respectively, in Kaplan-Meier method with log-rank).

CONCLUSION

Hepatic perfusion CT yields early imaging biomarkers for predicting overall survival in HCC patients treated with sorafenib.

Diagnostic value of dynamic contrast-enhanced CT with perfusion imaging in the quantitative assessment of tumor response to sorafenib in patients with advanced hepatocellular carcinoma: A feasibility study

PURPOSE

To investigate the feasibility of perfusion-CT (p-CT) measurements in quantitative assessment of hemodynamic changes related to sorafenib in patients with advanced hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty-two patients with advanced HCC underwent p-CT study (256-MDCT scanner) before and 2 months after sorafenib administration. Dedicated perfusion software generated a quantitative map of arterial and portal perfusion and calculated the following perfusion parameters in target liver lesion: hepatic perfusion (HP), time-to-peak (TTP), blood volume (BV), arterial perfusion (AP), and hepatic perfusion index (HPI). After the follow-up scan, patients were categorized as responders and non-responders, according to mRECIST. Perfusion values were analyzed and compared in HCC lesions and in the cirrhotic parenchyma (n=22), such as between baseline and follow-up in progressors and non-progressors.

RESULTS

Before treatment, all mean perfusion values were significantly higher in HCC lesions than in the cirrhotic parenchyma (HP 47.8±17.2 vs 13.3±6.3mL/s per 100g; AP 47.9±18.1 vs 12.9±10.7mL/s; p<0.001). The group that responded to sorafenib (n=17) showed a significant reduction of values in HCC target lesions after therapy (HP 29.2±23.3 vs 48.1±15.1; AP 29.4±24.6 vs 49.2±17.4; p<0.01), in comparison with the non-responder group (n=5) that demonstrated no significant variation before and after treatment of HP (46.9±25.1 vs 46.7±24.1) and AP (43.4±21.7 vs 43.5±24.6). Among the responder group, HP percentage variation (Δ) in target lesions, during treatment, showed a significantly different (p=0.04) ΔHP in the group with complete response (79%) compared to the group with partial response or stable disease (16%).

CONCLUSIONS

p-CT technique can be used for HCC quantitative assessment of changes related to anti-angiogenic therapy. Identification of response predictors might help clinicians in selection of patients who may benefit from targeted-therapy allowing for optimization of individualized treatment.

Functional imaging in liver tumours

Functional imaging encompasses techniques capable of assessing physiological parameters of tissues, and offers useful clinical information in addition to that obtained from morphological imaging. Such techniques may include magnetic resonance imaging with diffusion-weighted sequences or hepatobiliary contrast agents, perfusion imaging, or molecular imaging with radiolabelled tracers. The liver is of major importance in oncological practice; not only is hepatocellular carcinoma one of the malignancies with steadily rising incidence worldwide, but hepatic metastases are regularly observed with a range of solid neoplasms. Within the realm of hepatic oncology, different functional imaging modalities may occupy pivotal roles in lesion characterisation, treatment selection and follow-up, depending on tumour size and type. In this review, we characterise the major forms of functional imaging, discuss their current application to the management of patients with common primary and secondary liver tumours, and anticipate future developments within this field.

Doppler ultrasonography helps discriminate between cirrhotic and non-cirrhotic patients with viral B and C hepatitis

OBJECTIVE

The aim of this study was to define the cutoff values between compensated cirrhosis and non-cirrhotic patients with viral hepatitis B and C, using the criteria of the Doppler parameters of liver vascularity.

MATERIALS AND METHODS

Seventy non-cirrhotic patients with viral hepatitis B and C and 30 cirrhotic patients were included in this prospective study. The diagnostic decisiveness properties of the Doppler values in the pre-determination of liver cirrhosis were evaluated using receiver operating characteristics curve analysis.

RESULTS

Taking the cutoff value for hepatic vein waveform index as 0.605, a sensitivity of 80% and a specificity of 77.1% were obtained. The sensitivity was 80%, and the specificity was 68.6% for a mean max portal velocity cutoff value of 18.25cm/s. When the hepatic artery resistivity index cutoff value was taken as 0.705 for the diagnosis of cirrhosis, the sensitivity was 82.5% and the specificity 72.1%. For a hepatic artery pulsatility index cutoff value of 1.295, a sensitivity of 82.5% and a specificity of 72.1% were found.

CONCLUSION

It is not possible to diagnose cirrhosis with only hemodynamic changes. However, the cutoff values may be helpful in the selection of patients to undergo the procedure of liver biopsy.

Imaging modalities for the diagnosis of hepatic fibrosis and cirrhosis

Non-invasive methods for liver fibrosis diagnosis are now commonly used as first-intention tests for liver fibrosis diagnosis in chronic liver diseases. Even morphological parameters provided by ultrasound is now challenged by blood fibrosis tests and transient elastography, in experienced hands, it performed well and in certain situations, imaging can still be useful to detect patients with fibrosis. In parallel, to ultrasound and Doppler imaging, various methodologies have been explored. Some of them remain confined to clinical research for the moment, as perfusion, MR diffusion-weighted imaging, intravoxel incoherent motion or acoustic structure quantification; others have already taken a place in clinical practice. Regarding fast growing of new technology some methods may become available for daily practice in the near future. Ultrasound tools or automated quantification of different physical parameters of imaging data could provide an opportunity for early diagnosis of liver diseases; MRI techniques could lead to the development of a "global" liver examination.

[Quantitative imaging in uro-oncology]

INTRODUCTION

Imaging currently performed in uro-oncology could provide useful information. The use of all this information could help to better understand tumor growth and response to treatment. Therefore, it seems interesting to review the knowledge, to describe the main techniques currently available in many centers or in process and to clarify their results.

MATERIALS AND METHODS

A systematic literature review was conducted in the PubMed database to identify all imaging techniques performed for therapeutic evaluation in uro-oncology. The keywords used were: cancer, kidney, bladder, prostate, urology biomarkers, imaging, ultrasound, CT-scan, MRI, PET-CT, RECIST, BOLD, ASL, gold DWI Diffusion, contrast, F-miso. The first publications identified were analyzed to search unidentified studies by the selected keywords.

RESULTS

From simple to more complex morphology data from functional imaging (PET, MRI), data obtained from imaging helps to better understand tumor growth and response to treatment. Although optimizations are coming, all the techniques reported are available in many centers or going to be.

CONCLUSION

The imaging evaluation in onco-urology can bring a large amount of information. Integrating to research protocols is now essential to sustain this activity.

Preoperative evaluation of colorectal liver metastases: comparison of gadopentetate dimeglumine and gadoxetic-acid-enhanced 1.5-T MRI

PURPOSE

The aim of this study was to compare the diagnostic performance of gadopentetate dimeglumine and gadoxetic-acid-enhanced MRI in patients with colorectal liver metastases.

METHODS

Thirty patients were included and divided into three sets, as follows: gadopentetate dimeglumine set-hepatic arterial phase, portal venous phase, and delay phase; gadoxetic acid set-hepatic arterial phase, portal venous phase, and delay phase; combined set-gadoxetic acid set and hepatobiliary phase. The accuracy was assessed by the area under the alternative-free response receiver operating characteristic curve; the sensitivity and positive predictive value were calculated.

RESULTS

There were 81 colorectal liver metastases in all. Both readers noted higher diagnostic accuracies of the combined set than the other two sets. In the group of small lesions, both readers detected significantly higher sensitivities and positive predictive value on the combined set than the other two sets.

CONCLUSIONS

The combined set showed higher accuracy and sensitivity, especially significantly higher accuracy and sensitivity on small lesions.