Multiparametric MRI analysis for the evaluation of MR‐guided high intensity focused ultrasound tumor treatment

Abstract

Nicolay, K. (2015). Multiparametric MRI analysis for the evaluation of MR-guided high intensity focused ultrasound tumor treatment. NMR in Biomedicine, 28(9), 1125-1140. DOI: 10.1002/nbm.3350 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. For the clinical application of high intensity focused ultrasound (HIFU) for thermal ablation of malignant tumors, accurate treatment evaluation is of key importance. In this study, we have employed a multiparametric MRI protocol, consisting of quantitative T 1 , T 2 , ADC, amide proton transfer (APT), T 1ρ and DCE-MRI measurements, to evaluate MR-guided HIFU treatment of subcutaneous tumors in rats. K-means clustering using all different combinations of the endogenous contrast MRI parameters (feature vectors) was performed to segment the multiparametric data into tissue populations with similar MR parameter values. The optimal feature vector for identification of the extent of non-viable tumor tissue after HIFU treatment was determined by quantitative comparison between clustering-derived and histology-derived non-viable tumor fractions. The highest one-to-one correspondence between these clustering-based and histology-based non-viable tumor fractions was observed for the feature vector {ADC, APT-weighted signal} (R 2 to line of identity (R 2 y=x ) = 0.92) and the strongest agreement was seen 3 days after HIFU (R 2 y=x = 0.97). To compare the multiparametric MRI analysis results with conventional HIFU monitoring and evaluation methods, the histology-derived non-viable tumor fractions were also quantitatively compared with nonperfused tumor fractions (derived from the level of contrast enhancement in the DCE-MRI measurements) and 240 CEM tumor fractions (i.e. thermal dose > 240 cumulative equivalent minutes at 43°C). The correlation between histology-derived non-viable tumor fractions directly after HIFU and the 240 CEM fractions was high, but not significant. The non-perfused fractions overestimated the extent of non-viable tumor tissue directly after HIFU, whereas an underestimation was observed 3 days after HIFU.In conclusion, we have shown that a multiparametric MR analysis, especially based on the ADC and the APTweighted signal, can potentially be used to determine the extent of non-viable tumor tissue 3 days after HIFU treatment. We expe...

Assessing high‐intensity focused ultrasound treatment of prostate cancer with hyperpolarized 13C dual‐agent imaging of metabolism and perfusion

“…It is important to note that in this study neither tumor volume nor water ADC predicted effective ablation. Similar to prior publications, we observed an early non‐significant decrease in ADC, and a trend towards increasing water ADC over time in the ablated region . Additionally, at 5 d after treatment the ADC was higher in the ablated zone than in the partially treated zone, consistent with the literature .…”

“…The early reduction in HP 13 C urea and its relationship to increased tumor hypoxia is consistent with a prior study, which reported that reduced 13 C urea AUC was associated with increased hypoxia in high‐ versus low‐grade TRAMP tumors . The clinical gold standard for measuring effective HIFU is DCE MRI, and the observed decrease in K trans and DCE MRI AUC immediately after HIFU and its recovery days after treatment have repeatedly been demonstrated in other studies . However, it is important to note that, if follow‐up HIFU is required to treat residual tumor after the initial DCE MRI, entrapped contrast agent within coagulated tissue regions could negatively impact the accuracy of the proton resonance frequency shift MR thermometry .…”

MRI methods for the evaluation of high intensity focused ultrasound tumor treatment: Current status and future needs

“…Cell lysis that is associated with necrosis generally leads to elevated tissue ADC values . Indeed, a strongly significant ( P < 0.001) ADC increase has been observed at 1 week after HIFU treatment of human liver tumors and at 3 days after treatment of mouse and rat subcutaneous tumors. In the latter study, in which we treated the rat tumors in a clinical 3Tesla (T) MR‐guided HIFU system, an average ADC increase of 0.51 × 10 −3 mm 2 /s was observed at 3 days after therapy.…”

“…In a later study, we have performed multiparametric MRI consisting of T 1 , T 2 , ADC, APT‐weighted signal, and T 1ρ mapping to evaluate MR‐guided HIFU treatment of rat tumors in a clinical 3T MR‐HIFU system. The cluster analysis showed that the extent of nonviable tumor tissue could be accurately determined at 3 days after HIFU treatment when the ADC and APT‐weighted signal data were combined .…”

Assessment of acute thermal damage volumes in muscle using magnetization‐prepared 3D T2‐weighted imaging following MRI‐guided high‐intensity focused ultrasound therapy

“…40 Protein denaturation, a cause of thermally induced cell death, has been detected using magnetization transfer, amide proton transfer, and T 1 q techniques. 15,18,19 Irreversible protein damage also causes increased tissue stiffness detectable using MR elastography, 16 but sublethal heating has a contradictory effect, and the method depends on the ability to apply imaging-synchronized mechanical waves to the tissue of interest. Finally, when a time series of MR temperature maps is available, the delivered thermal dose can be calculated.…”