Intravoxel incoherent motion MRI: emerging applications for nasopharyngeal carcinoma at the primary site

Discrimination between Metastatic and Nonmetastatic Mesorectal Lymph Nodes in Rectal Cancer Using Intravoxel Incoherent Motion Diffusion-weighted Magnetic Resonance Imaging

RATIONALE AND OBJECTIVES

The aim of the study was to investigate the diagnostic value of intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (IVIM DWI) for discriminating nonmetastatic from metastatic mesorectal lymph nodes in rectal cancer.

MATERIALS AND METHODS

IVIM DWI was performed preoperatively on 50 patients with rectal carcinoma. The short-axis diameter, short- to long-axis diameter ratio, and IVIM-based parameter (pure diffusion coefficient [D], pseudo-diffusion coefficient [D*] and perfusion fraction [f]) values were compared between the metastatic and nonmetastatic lymph node groups.

RESULTS

The short-axis diameter; short- to long-axis diameter ratio; and D, D*, and f values for the nonmetastatic lymph node group (n = 28) were 6.446 ± 1.201 mm, 0.815 ± 0.099, 1.071 ± 0.234 × 10(-3) mm(2)/s, 15.443 ± 5.946 mm(2)/s and 0.261 ± 0.128, respectively, and were 9.045 ± 3.185 mm, 0.809 ± 0.099, 0.816 ± 0.121 × 10(-3) mm(2)/s, 11.679 ± 7.521 × 10(-3) mm(2)/s, and 0.190 ± 0.064, respectively, for the metastatic lymph node group (n = 31). The short-axis diameter for the metastatic group was significantly higher than for the nonmetastatic group (P <0.001). The metastatic group exhibited significantly lower D and D* values than the nonmetastatic group (P <0.01). The short- to long-axis diameter ratio and f values did not differ significantly between the two groups. Optimal cutoff values (area under the curve, sensitivity, and specificity) for distinguishing metastatic from nonmetastatic lymph nodes were as follows: short-axis diameter = 5.563 mm (0.783, 74.2%, 82.1%); D = 0.667 × 10(-3) mm(2)/s (0.885, 77.4%, 89.3%); and D* = 0.485 × 10(-3) mm(2)/s (0.727, 80.6%, 67.9%).

CONCLUSION

IVIM DWI is useful to differentiate between metastatic and nonmetastatic mesorectal lymph nodes in rectal cancer.

Dynamic contrast-enhanced MRI, diffusion-weighted MRI and 18F-FDG PET/CT for the prediction of survival in oropharyngeal or hypopharyngeal squamous cell carcinoma treated with chemoradiation

OBJECTIVES

We prospectively investigated the roles of pretreatment dynamic contrast-enhanced MR imaging (DCE-MRI), diffusion-weighted MR imaging (DWI) and ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG PET)/CT for predicting survival of oropharyngeal or hypopharyngeal squamous cell carcinoma (OHSCC) patients treated with chemoradiation.

METHODS

Patients with histologically proven OHSCC and neck nodal metastases scheduled for chemoradiation were eligible. Clinical variables as well as DCE-MRI-, DWI- and ¹⁸F-FDG PET/CT-derived parameters of the primary tumours and metastatic neck nodes were analysed in relation to 3-year progression-free survival (PFS) and overall survival (OS) rates.

RESULTS

Eighty-six patients were available for analysis. Multivariate analysis identified the efflux rate constant (K _ep)-tumour < 3.79 min^-1 (P = 0.001), relative volume of extracellular extravascular space (V _e)-node < 0.23 (P = 0.004) and SUV_max-tumour > 19.44 (P = 0.025) as independent risk factors for both PFS and OS. A scoring system based upon the sum of each of the three imaging parameters allowed stratification of our patients into three groups (patients with 0/1 factor, patients with 2 factors and patients with 3 factors, respectively) with distinct PFS (3-year rates = 72 %, 38 % and 0 %, P < 0.0001) and OS (3-year rates = 81 %, 46 % and 20 %, P < 0.0001).

CONCLUSIONS

K _ep-tumour, V _e-node and SUV_max-tumour were independent prognosticators for OHSCC treated with chemoradiation. Their combination helped survival stratification.

KEY POINTS

• K _ep -tumour, V _e -node and SUV _max -tumour are independent predictors of survival rates. • The combination of these three prognosticators may help stratification of survival. • MRI and FDG-PET/CT play complementary roles in prognostication of head and neck cancer.

Intravoxel incoherent motion MR imaging for breast lesions: comparison and correlation with pharmacokinetic evaluation from dynamic contrast-enhanced MR imaging

OBJECTIVES

To compare diagnostic performance for breast lesions by quantitative parameters derived from intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and to explore whether correlations exist between these parameters.

METHODS

IVIM and DCE MRI were performed on a 1.5-T MRI scanner in patients with suspicious breast lesions. Thirty-six breast cancers and 23 benign lesions were included in the study. Quantitative parameters from IVIM (D, f and D*) and DCE MRI (K^trans, K_ep, V_e and V_p) were calculated and compared between malignant and benign lesions. Spearman correlation test was used to evaluate correlations between them.

RESULTS

D, f, D* from IVIM and K^trans, K_ep, V_p from DCE MRI were statistically different between breast cancers and benign lesions (p < 0.05, respectively) and D demonstrated the largest area under the receiver-operating characteristic curve (AUC = 0.917) and had the highest specificity (83 %). The f value was moderately statistically correlated with V_p (r = 0.692) and had a poor correlation with K^trans (r = 0.456).

CONCLUSIONS

IVIM MRI is useful in the differentiation of breast lesions. Significant correlations were found between perfusion-related parameters from IVIM and DCE MRI. IVIM may be a useful adjunctive tool to standard MRI in diagnosing breast cancer.

KEY POINTS

• IVIM provided diffusion as well as perfusion information • IVIM could help differential diagnosis of breast lesions • Correlations were found between perfusion-related parameters from IVIM and DCE MRI.

Intravoxel Incoherent Motion MR Imaging for Staging of Hepatic Fibrosis

Objectives

To determine the potential of intravoxel incoherent motion (IVIM) MR imaging for staging of hepatic fibrosis (HF).

Methods

We searched PubMed and EMBASE from their inception to 31 July 2015 to select studies reporting IVIM MR imaging and HF staging. We defined F1-2 as non-advanced HF, F3-4 as advanced HF, F0 as normal liver, F1 as very early HF, and F2-4 as significant HF. Then we compared stage F0 with F1, F0-1 with F2-3, and F1-2 with F3-4 using IVIM-derived parameters (pseudo-diffusion coefficient D*, perfusion fraction f, and pure molecular diffusion parameter D). The effect estimate was expressed as a pooled weighted mean difference (WMD) with 95% confidence interval (CI), using the fixed-effects model.

Results

Overall, we included six papers (406 patients) in this study. Significant differences in D* were observed between F0 and F1, F0-1 and F2-3, and F1-2 and F3-4 (WMD 2.46, 95% CI 0.83–4.09, P = 0.006; WMD 13.10, 95% CI 9.53–16.67, P < 0.001; WMD 14.34, 95% CI 10.26–18.42, P < 0.001, respectively). Significant differences in f were also found between F0 and F1, F0-1 and F2-3, and F1-2 and F3-4 (WMD 1.62, 95% CI 0.06–3.18, P = 0.027; WMD 5.63, 95% CI 2.74–8.52, P < 0.001; WMD 3.30, 95% CI 2.10–4.50, P < 0.001, respectively). However, D showed no differences between F0 and F1, F0-1 and F2-3, and F1-2 and F3-4 (WMD 0.05, 95% CI -0.01─0.11, P = 0.105; WMD 0.04, 95% CI -0.01─0.10, P = 0.230; WMD 0.02, 95% CI -0.02─0.06, P = 0.378, respectively).

Conclusions

IVIM MR imaging provides an effective method of staging HF and can distinguish early HF from normal liver, significant HF from normal liver or very early HF, and advanced HF from non-advanced HF.

Intravoxel Incoherent Motion Diffusion-weighted Magnetic Resonance Imaging for Monitoring the Early Response to ZD6474 from Nasopharyngeal Carcinoma in Nude Mouse

Early therapeutic effects of anti-angiogenic agent ZD6474 upon nasopharyngeal carcinoma (NPC) in nude mouse were monitored by using intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI). Mice bearing NPC underwent IVIM DWI at baseline and after 1, 3, and 7 days of treatment with ZD6474 or vehicle (n = 12 per group). Parameters of apparent diffusion coefficient (ADC), true diffusion coefficient (D), perfusion fraction (f), and blood pseudodiffusion coefficient (D*) at different time points were compared between the two groups or within the treated group. In the treated group, the perfusion-related parameters f and D* of the tumors decreased significantly on day 1 while the diffusion-related parameters ADC and D were significantly higher beginning on day 3 compared with the control group. The decreases in f on day 1 and D* on day 3 were moderately correlated with the smaller tumor size change on day 7. Moderate correlations were established between MVD and f and D* as well as between increased TUNEL or decreased Ki-67 index and ADC and D. This study supports that IVIM DWI is sensitive to detect the ZD6474-induced changes in NPC in nude mouse and the f parameter could predict early response to anti-angiogenic treatment.

Intravoxel Incoherent Motion-Magnetic Resonance Imaging as an Early Predictor of Treatment Response to Neoadjuvant Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma

The aim of the study was to prospectively evaluate the clinical value of intravoxel incoherent motion (IVIM)-magnetic resonance imaging (MRI) in early predicting the treatment response to neoadjuvant chemotherapy (NAC) for nasopharyngeal carcinoma (NPC). Forty-eight patients with locoregionally advanced NPC were imaged with IVIM-MRI (14 b-factors, 0-1000 s/mm2) on a 3.0-T Magnetic resonance system, at the baseline, and repeatedly at the third and 21st day after NAC started. The IVIM-derived parameters (D*, pure diffusion coefficient; f, perfusion fraction; and D, pseudodiffusion coefficient) were calculated with the Interactive Data Language version 6.3 software. The baseline parameters and their corresponding changes (Δparameter(day)) during NAC were compared using the Student t test or Mann-Whitney U test. Variation analyses of IVIM-derived parameters were tested with intraclass correlation coefficient. Receiver-operating characteristic (ROC) curve analysis was conducted to estimate the best diagnostic accuracy. Statistical analyses were performed on the SPSS 18.0 software, with a 2-tailed probability value, P < 0.05 was considered significant. Among recruited patients, 37 cases were categorized as responders and 11 cases as nonresponders after NAC completed. The intra- and interobserver intraclass correlation coefficient of IVIM-derived parameters were excellent, which ranged from 0.858 to 0.971. Compared with the baseline value, at the third and 21st day, the D value was significantly higher and the D* value significantly lower (P < 0.05, P < 0.001, respectively). In contrast, f parameter only changed slightly (P > 0.05). Compared with nonresponders, responders presented a notably lower baseline D value and higher ΔD3, ΔD21, ΔD3*, ΔD21*, and Δf21 (P < 0.05), but no significant change in Δf3 was observed (P > 0.1). The receiver-operating characteristic curve analyses indicated that the threshold of baseline D values that best predicted the responders for primary nasopharynx tumors and metastatic lymph nodes were 0.911  × 10(-3) mm2/s versus 0.951 × 10(-3) mm2/s, and their corresponding area under curve, sensitivity, and specificity were 0.714 versus 0.774, 0.658 versus 0.538, and 0.818 versus 0.944, respectively. IVIM-MRI can potentially early predict the treatment response of NAC for NPC patients. The baseline D value, and early changes in D and D value are better predictors of the chemotherapeutic responsiveness.