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 magnetic resonance imaging to predict vesicoureteral reflux in children with urinary tract infection

Objectives

To compare the diffusion parameters of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) between the “reflux” and the “non-reflux” kidneys, and to evaluate the feasibility of using IVIM DWI to predict vesicoureteral reflux (VUR) in children with a urinary tract infection (UTI).

Methods

Eighty-three kidneys from 57 pediatric patients with a UTI were classified into “reflux” and “non-reflux” groups according to voiding cystourethrography (VCUG) results. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (PF) were measured and compared in the renal pelvis of both groups. Four indices (D*/ADC, PF/ADC, D*/D, and PF/D) were calculated and receiver operating characteristic (ROC) curve analyses were performed.

Results

VURs were detected on VCUG in 21 kidneys. PF and D* were significantly higher in the “reflux” group than in the “non-reflux” group. The indices were all significantly higher. The PF/D index showed the best diagnostic performance in predicting VUR in children with UTI (A_z?=?0.864).

Conclusion

PF and D* were significantly higher in the "reflux" kidney than in the "non-reflux" kidney. Our new index (PF/D) could prove useful for predicting VUR.

Key Points

? IVIM DWI is both radiation-free and contrast media-free. ? IVIM DWI index is easily calculated by combining diffusion parameters. ? IVIM DWI may help predict VUR in children with UTI. ? PF is significantly higher in the “reflux” than the “non-reflux” kidneys. ? A new VUR index, PF/D could prove useful for predicting VUR.

     

Using intravoxel incoherent motion MR imaging to study the renal pathophysiological process of contrast-induced acute kidney injury in rats: Comparison with conventional DWI and arterial spin labelling

Objectives

To investigate the potential of intravoxel incoherent motion (IVIM) to assess the renal pathophysiological process in contrast-induced acute kidney injury (CIAKI).

Methods

Twenty-seven rats were induced with CIAKI model, six rats were imaged longitudinally at 24 h prior to and 30 min, 12, 24, 48, 72 and 96 h after administration; three rats were randomly chosen from the rest for serum creatinine and histological studies. D, f, D* and ADC were calculated from IVIM, and renal blood flow (RBF) was obtained from arterial spin labelling (ASL).

Results

A progressive reduction in D and ADC was observed in cortex (CO) by 3.07 and 8.62 % at 30 min, and by 25.77 and 28.16 % at 48 h, respectively. A similar change in outer medulla (OM) and inner medulla (IM) was observed at a later time point (12–72 h). D values were strongly correlated with ADC (r?=?0.885). As perfusion measurement, a significant decrease was shown for f in 12–48 h and an increase in 72–96 h. A slightly different trend was found for D*, which was decreased by 26.02, 21.78 and 10.19 % in CO, OM and IM, respectively, at 30 min. f and D* were strongly correlated with RBF in the cortex (r?=?0.768, r?=?0.67), but not in the medulla.

Conclusions

IVIM is an effective imaging tool for monitoring progress in renal pathophysiology undergoing CIAKI.

Key Points

? IVIM analysis permits separate quantification of diffusion and perfusion. ? IVIM can provide useful biomarkers ifor changes in renal pathophysiology. ? IVIM can be useful for monitoring progress in renal pathophysiology undergoing CIAKI.

     

Prediction of the treatment outcome using intravoxel incoherent motion and diffusional kurtosis imaging in nasal or sinonasal squamous cell carcinoma patients

Objectives

To evaluate the diagnostic value of intravoxel incoherent motion (IVIM) and diffusional kurtosis imaging (DKI) parameters in nasal or sinonasal squamous cell carcinoma (SCC) patients to determine local control/failure.

Methods

Twenty-eight patients were evaluated. MR acquisition used single-shot spin-echo EPI with 12 b-values. Quantitative parameters (mean value, 25th, 50th and 75th percentiles) of IVIM (perfusion fraction f, pseudo-diffusion coefficient D*, and true-diffusion coefficient D), DKI (kurtosis value K, kurtosis corrected diffusion coefficient D_k) and apparent diffusion coefficient (ADC) were calculated. Parameter values at both the pretreatment and early-treatment period, and the percentage change between these two periods were obtained.

Results

Multivariate logistic regression analysis: the percentage changes of D (mean, 25th, 50th, 75th), K (mean, 50th, 75th), Dk (mean, 25th, 50th), and ADC (mean, 25th, 50th) were predictors of local control. ROC curve analysis: the parameter with the highest accuracy = the percentage change of D value with the histogram 25th percentile (0.93 diagnostic accuracy). Multivariate Cox regression analyses: the percentage changes of D (mean, 25th, 50th), K (mean, 50th, 75th), Dk (mean, 25th, 50th) and ADC (mean, 25th, 50th) are predictors.

Conclusions

IVIM and DKI parameters, especially the D-value’s histogram 25th percentile, are useful for predicting local control.

Key Points

? Noninvasive assessment of treatment outcome in SCC patients was achieved using IVIM/DKI.? Several IVIM and DKI parameters can predict the local control.? Especially, the D-value’s histogram 25th percentile has high diagnostic accuracy.

     

Differentiation of malignant from benign soft tissue tumours: use of additive qualitative and quantitative diffusion-weighted MR imaging to standard MR imaging at 3.0 T

Objectives

To determine the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) to differentiate malignant from benign soft tissue tumours at 3.0 T.

Methods

3.0 T MR images including DWI in 63 patients who underwent surgery for soft tissue tumours were retrospectively analyzed. Two readers independently interpreted MRI for the presence of malignancy in two steps: standard MRI alone, standard MRI and DWI with qualitative and quantitative analysis combined.

Results

There were 34 malignant and 29 non-malignant soft tissue tumours. In qualitative analysis, hyperintensity relative to skeletal muscle was more frequent in malignant than benign tumours on DWI (P=0.003). In quantitative analysis, ADCs of malignant tumours were significantly lower than those of non-malignant tumours (P≤0.002): 759±385 vs. 1188±423 μm²/sec minimum ADC value, 941±440 vs. 1310±440 μm²/sec average ADC value. The mean sensitivity, specificity and accuracy of both readers were 96 %, 72 %, and 85 % on standard MRI alone and 97 %, 90 %, and 94 % on standard MRI with DWI.

Conclusions

The addition of DWI to standard MRI improves the diagnostic accuracy for differentiation of malignant from benign soft tissue tumours at 3.0 T.

Key Points

? DWI has added value for differentiating malignant from benign soft tissue tumours. ? Addition of DWI to standard MRI at 3.0 T improves the diagnostic accuracy. ? Measurements of both ADC _min within solid portion and ADC _av are helpful.

     

Diffusion-weighted imaging of breast lesions: Region-of-interest placement and different ADC parameters influence apparent diffusion coefficient values

Objectives

To investigate the influence of region-of-interest (ROI) placement and different apparent diffusion coefficient (ADC) parameters on ADC values, diagnostic performance, reproducibility and measurement time in breast tumours.

Methods

In this IRB-approved, retrospective study, 149 histopathologically proven breast tumours (109 malignant, 40 benign) in 147 women (mean age 53.2) were investigated. Three radiologists independently measured minimum, mean and maximum ADC, each using three ROI placement approaches:1 – small 2D-ROI, 2 – large 2D-ROI and 3 – 3D-ROI covering the whole lesion. One reader performed all measurements twice. Median ADC values, diagnostic performance, reproducibility, and measurement time were calculated and compared between all combinations of ROI placement approaches and ADC parameters.

Results

Median ADC values differed significantly between the ROI placement approaches (p?<?.001). Minimum ADC showed the best diagnostic performance (AUC .928–.956), followed by mean ADC obtained from 2D ROIs (.926–.94). Minimum and mean ADC showed high intra- (ICC .85–.94) and inter-reader reproducibility (ICC .74–.94). Median measurement time was significantly shorter for the 2D ROIs (p?<?.001).

Conclusions

ROI placement significantly influences ADC values measured in breast tumours. Minimum and mean ADC acquired from 2D-ROIs are useful for the differentiation of benign and malignant breast lesions, and are highly reproducible, with rapid measurement.

Key Points

? Region of interest placement significantly influences apparent diffusion coefficient of breast tumours. ? Minimum and mean apparent diffusion coefficient perform best and are reproducible. ? 2D regions of interest perform best and provide rapid measurement times.

     

Evaluation of breast cancer using intravoxel incoherent motion (IVIM) histogram analysis: comparison with malignant status,histological subtype,and molecular prognostic factors

Purpose

To examine heterogeneous breast cancer through intravoxel incoherent motion (IVIM) histogram analysis.

Materials and methods

This HIPAA-compliant, IRB-approved retrospective study included 62 patients (age 48.44?±?11.14 years, 50 malignant lesions and 12 benign) who underwent contrast-enhanced 3 T breast MRI and diffusion-weighted imaging. Apparent diffusion coefficient (ADC) and IVIM biomarkers of tissue diffusivity (D_t), perfusion fraction (f_p), and pseudo-diffusivity (D_p) were calculated using voxel-based analysis for the whole lesion volume. Histogram analysis was performed to quantify tumour heterogeneity. Comparisons were made using Mann–Whitney tests between benign/malignant status, histological subtype, and molecular prognostic factor status while Spearman’s rank correlation was used to characterize the association between imaging biomarkers and prognostic factor expression.

Results

The average values of the ADC and IVIM biomarkers, D_t and f_p, showed significant differences between benign and malignant lesions. Additional significant differences were found in the histogram parameters among tumour subtypes and molecular prognostic factor status. IVIM histogram metrics, particularly f_p and D_p, showed significant correlation with hormonal factor expression.

Conclusion

Advanced diffusion imaging biomarkers show relationships with molecular prognostic factors and breast cancer malignancy. This analysis reveals novel diagnostic metrics that may explain some of the observed variability in treatment response among breast cancer patients.

Key Points

? Novel IVIM biomarkers characterize heterogeneous breast cancer.? Histogram analysis enables quantification of tumour heterogeneity.? IVIM biomarkers show relationships with breast cancer malignancy and molecular prognostic factors.

     

Differentiation of benign and malignant solid pancreatic masses using magnetic resonance elastography with spin-echo echo planar imaging and three-dimensional inversion reconstruction: a prospective study

Objectives

To determine the diagnostic performance of MR elastography (MRE) and compare it with serum CA19-9 in differentiating malignant from benign pancreatic masses, with emphasis on differentiating between pancreatic ductal adenocarcinoma (PDAC) and mass-forming pancreatitis (MFP).

Methods

We performed a prospective, consecutive, 24-month study in 85 patients with solid pancreatic masses confirmed by histopathologic examinations. The mass stiffness and stiffness ratio (calculated as the ratio of mass stiffness to the parenchymal stiffness) were assessed. The diagnostic accuracy was analysed by calculating the area under the ROC curve (AUROC).

Results

The final diagnosis included 54 malignant tumours (43 patients with PDAC) and 31 benign masses (24 patients with MFP). The stiffness ratio showed better diagnostic performance than the mass stiffness and serum CA19-9 for the differentiation between malignant and benign masses (AUC: 0.912 vs. 0.845 vs. 0.702; P = 0.026, P < 0.001) and, specifically, between PDAC and MFP (AUC: 0.955 vs. 0.882 vs. 0.745; P = 0.026, P = 0.003). The sensitivity, specificity, and accuracy of stiffness ratio for the differentiation of PDAC and MFP were all higher than 0.9.

Conclusions

MRE presents an effective and quantitative strategy for non-invasive differentiation between PDAC and MFP based on their mechanical properties.

Key Points

? 3D MRE is useful for calculating stiffness of solid pancreatic tumours. ? Stiffness ratio outperformed stiffness and CA19-9 for differentiating PDAC from MFP. ? Incorporation of 3D MRE into a standard MRI protocol is recommended.

     

Cardiac-gated intravoxel incoherent motion diffusion-weighted magnetic resonance imaging for the investigation of intracranial cerebrospinal fluid dynamics in the lateral ventricle: a feasibility study

Purpose

Intravoxel incoherent motion (IVIM) in diffusion-weighted magnetic resonance imaging (DW-MRI) attributes the signal attenuation to the molecular diffusion and to a faster pseudo-diffusion. Purpose of the study was to demonstrate the feasibility of IVIM for the investigation of intracranial cerebrospinal fluid (CSF) dynamics.

Methods

Cardiac-gated DW-MRI images with fifteen b-values (0–1300s/mm²) along three orthogonal directions (mediolateral (ML), anteroposterior (AP), and craniocaudal (CC)) were acquired during maximum systole and diastole in 10 healthy volunteers (6 males, mean age 36?±?15 years). A pixel-wise bi-exponential fitting with an iterative nonparametric algorithm was carried out to calculate the following parameters: diffusion coefficient (D), fast diffusion coefficient (D*), and fraction of fast diffusion (f). Region of interest measurements were performed in both lateral ventricles. Comparison of IVIM parameters was performed among two cardiac cycle acquisitions and among the diffusion-encoding directions using a paired Student’s t test.

Results

f significantly (p?<?0.05) depended on the diffusion-encoding direction and on the cardiac cycle (diastole AP 0.30?±?0.13, ML 0.22?±?0.12, CC 0.26?±?0.17; systole AP 0.45?±?0.17, ML 0.34?±?0.15, CC 0.40?±?0.21). Neither a cardiac cycle nor a direction dependency was found among mean D values (which is in line with the expected intraventricular isotropic diffusion) and D* values (p?>?0.05 each).

Conclusion

The fraction of fast diffusion from IVIM is feasible to detect a direction-dependent and cardiac-dependent pulsatile CSF flow within the lateral ventricles allowing for quantitative monitoring of CSF dynamics. This technique might provide opportunities to further investigate the pathophysiology of various neurological disorders involving altered CSF dynamics.

     

Dynamic contrast-enhanced and diffusion-weighted MR imaging in the characterisation of small,non-palpable solid testicular tumours

Objectives

To explore the role of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), using semiquantitative and quantitative parameters, and diffusion-weighted (DW) MRI in differentiating benign from malignant small, non-palpable solid testicular tumours.

Methods

We calculated the following DCE-MRI parameters of 47 small, non-palpable solid testicular tumours: peak enhancement (PE), time to peak (TTP), percentage of peak enhancement (Epeak), wash-in-rate (WIR), signal enhancement ratio (SER), volume transfer constant (K_trans), rate constant (K_ep), extravascular extracellular space volume fraction (V_e) and initial area under the curve (_iAUC). DWI signal intensity and apparent diffusion coefficient (ADC) values were evaluated.

Results

E_peak, WIR, K_trans , K_ep and iAUC were higher and TTP shorter in benign compared to malignant lesions (p?<?0.05). All tumours had similar ADC values (p > 0.07). Subgroup analysis limited to the most frequent histologies – Leydig cell tumours (LCTs) and seminomas – replicated the findings of the entire set. Best diagnostic cutoff value for identification of seminomas: K_trans ≤0.135 min^?1, K_ep ≤0.45 min^?1, iAUC ≤10.96, WIR ≤1.11, Epeak ≤96.72, TTP >99 s.

Conclusions

DCE-MRI parameters are valuable in differentiating between benign and malignant small, non-palpable testicular tumours, especially when characterising LCTs and seminomas.

Key Points

? DCE-MRI may be used to differentiate benign from malignant non-palpable testicular tumours. ? Seminomas show lower Ktrans, Kep and iAUC values. ? ADC values are not valuable in differentiating seminomas from LCTs. ? Semiquantitative DCE-MRI may be used to characterise small, solid testicular tumours.

     

Grading diffuse gliomas without intense contrast enhancement by amide proton transfer MR imaging: comparisons with diffusion- and perfusion-weighted imaging

Objectives

To investigate whether amide proton transfer (APT) MR imaging can differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) among gliomas without intense contrast enhancement (CE).

Methods

This retrospective study evaluated 34 patients (22 males, 12 females; age 36.0?±?11.3 years) including 20 with LGGs and 14 with HGGs, all scanned on a 3T MR scanner. Only tumours without intense CE were included. Two neuroradiologists independently performed histogram analyses to measure the 90th-percentile (APT₉₀) and mean (APT_mean) of the tumours’ APT signals. The apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) were also measured. The parameters were compared between the groups with Student’s t-test. Diagnostic performance was evaluated with receiver operating characteristic (ROC) analysis.

Results

The APT₉₀ (2.80?±?0.59 % in LGGs, 3.72?±?0.89 in HGGs, P?=?0.001) and APT_mean (1.87?±?0.49 % in LGGs, 2.70?±?0.58 in HGGs, P?=?0.0001) were significantly larger in the HGGs compared to the LGGs. The ADC and rCBV values were not significantly different between the groups. Both the APT₉₀ and APT_mean showed medium diagnostic performance in this discrimination.

Conclusions

APT imaging is useful in discriminating HGGs from LGGs among diffuse gliomas without intense CE.

Key Points

? Amide proton transfer (APT) imaging helps in grading non-enhancing gliomas ? High-grade gliomas showed higher APT signal than low-grade gliomas ? APT imaging showed better diagnostic performance than diffusion- and perfusion-weighted imaging

     

Pre-treatment magnetic resonance-based texture features as potential imaging biomarkers for predicting event free survival in anal cancer treated by chemoradiotherapy

Aim

To assess regular MRI findings and tumour texture features on pre-CRT imaging as potential predictive factors of event-free survival (disease progression or death) after chemoradiotherapy (CRT) for anal squamous cell carcinoma (ASCC) without metastasis.

Materials and methods

We retrospectively included 28 patients treated by CRT for pathologically proven ASCC with a pre-CRT MRI. Texture analysis was carried out with axial T2W images by delineating a 3D region of interest around the entire tumour volume. First-order analysis by quantification of the histogram was carried out. Second-order statistical texture features were derived from the calculation of the grey-level co-occurrence matrix using a distance of 1 (d1), 2 (d2) and 5 (d5) pixels. Prognostic factors were assessed by Cox regression and performance of the model by the Harrell C-index.

Results

Eight tumour progressions led to six tumour-specific deaths. After adjusting for age, gender and tumour grade, skewness (HR = 0.131, 95% CI = 0-0.447, p = 0.005) and cluster shade_d1 (HR = 0.601, 95% CI = 0-0.861, p = 0.027) were associated with event occurrence. The corresponding Harrell C-indices were 0.846, 95% CI = 0.697-0.993, and 0.851, 95% CI = 0.708-0.994.

Conclusion

ASCC MR texture analysis provides prognostic factors of event occurrence and requires additional studies to assess its potential in an “individual dose” strategy for ASCC chemoradiation therapy.

Key Points

? MR texture features help to identify tumours with high progression risk.? Texture feature maps help to identify intra-tumoral heterogeneity.? Texture features are a better prognostic factor than regular MR findings.

     

Multiparametric voxel-based analyses of standardized uptake values and apparent diffusion coefficients of soft-tissue tumours with a positron emission tomography/magnetic resonance system: Preliminary results

Objectives

To investigate the usefulness of voxel-based analysis of standardized uptake values (SUVs) and apparent diffusion coefficients (ADCs) for evaluating soft-tissue tumour malignancy with a PET/MR system.

Methods

Thirty-five subjects with either ten low/intermediate-grade tumours or 25 high-grade tumours were prospectively enrolled. Zoomed diffusion-weighted and fluorodeoxyglucose (¹⁸FDG)-PET images were acquired along with fat-suppressed T2-weighted images (FST2WIs). Regions of interest (ROIs) were drawn on FST2WIs including the tumour in all slices. ROIs were pasted onto PET and ADC-maps to measure SUVs and ADCs within tumour ROIs. Tumour volume, SUVmax, ADCminimum, the heterogeneity and the correlation coefficients of SUV and ADC were recorded. The parameters of high- and low/intermediate-grade groups were compared, and receiver operating characteristic (ROC) analysis was also performed.

Results

The mean correlation coefficient for SUV and ADC in high-grade sarcomas was lower than that of low/intermediate-grade tumours (?0.41?±?0.25 vs. ?0.08?±?0.34, P?<?0.01). Other parameters did not differ significantly. ROC analysis demonstrated that correlation coefficient showed the best diagnostic performance for differentiating the two groups (AUC 0.79, sensitivity 96.0%, specificity 60%, accuracy 85.7%).

Conclusions

SUV and ADC determined via PET/MR may be useful for differentiating between high-grade and low/intermediate-grade soft tissue tumours.

Key Points

? PET/MR allows voxel-based comparison of SUVs and ADCs in soft-tissue tumours. ? A comprehensive assessment of internal heterogeneity was performed with scatter plots. ? SUVmax or ADCminimum could not differentiate high-grade sarcoma from low/intermediate-grade tumours. ? Only the correlation coefficient between SUV and ADC differentiated the two groups. ? The correlation coefficient showed the best diagnostic performance by ROC analysis.

     

Correlation between conventional MR imaging combined with diffusion-weighted imaging and histopathologic findings in eyes primarily enucleated for advanced retinoblastoma: a retrospective study

Objectives

To determine the diagnostic accuracy of conventional MRI in detecting tumour invasion of advanced intraocular retinoblastoma and to correlate ADC values with high-risk prognostic parameters.

Method

The sensitivities, specificities, positive predictive values (PPV), negative predictive values (NPV) and accuracies of MRI in detecting tumour-extent parameters of 63 retinoblastomas were determined. Furthermore, ADC values were correlated with high-risk prognostic parameters.

Results

MRI detected postlaminar optic nerve with a sensitivity of 73.3% (95% CI 44.9–92.2%) and a specificity of 89.6% (77.3–96.5%), while the specificity for choroidal invasion was only 31.8% (13.9-54.9%). Likewise, MRI failed to predicted early optic nerve invasion in terms of low sensitivity and PPV. In contrast, scleral and ciliary body invasion could be correctly excluded with high NPV. ADC values were significantly lower in patients with undifferentiated tumours, large tumour size, as with optic nerve and scleral invasion (all p?<?0.05). However, no correlation was found between ADC values and the degree of choroidal or ciliary body infiltration. Additionally, ADC values were negatively correlated with Ki-67 index (r?=??0.62, P?=?0.002).

Conclusions

Conventional MRI has some limitations in reliably predicting microscopic infiltration, with the diagnostic efficiency showing room for improvement, whereas ADC values correlated well with certain high-risk prognostic parameters for retinoblastoma.

Key points

? Conventional MRI failed to predicted microscopic infiltration of the retinoblastoma.? Scleral and ciliary body invasion could be excluded with high NPV.? ADC values correlated well with some high-risk pathological prognostic parameters.

     

Evaluation of chronic inflammatory demyelinating polyneuropathy: 3D nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement imaging (3D SHINKEI)

Objective

To evaluate the usefulness of 3D nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement imaging (SHINKEI) in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).

Methods

This institutional review board-approved retrospective study included 14 CIDP patients and nine normal subjects. The signal-to-noise ratio (SNR), contrast ratio (CR), and the size of the cervical ganglions and roots were measured by two raters.

Results

The SNRs of the ganglions and roots were larger in patients with CIDP (9.55?±?3.87 and 9.81?±?3.64) than in normal subjects (7.21?±?2.42 and 5.70?±?2.14, P?<?0.0001, respectively). The CRs of the ganglions and roots were larger in patients with CIDP (0.77?±?0.08 and 0.68?±?0.12) than in normal subjects (0.72?±?0.07 and 0.53?±?0.11, P?<?0.0001, respectively). The sizes of the ganglions and the roots were larger in patients with CIDP (6.44?±?1.61 mm and 4.89?±?1.94 mm) than in normal subjects (5.24?±?1.02 mm and 3.39?±?0.80 mm, P?<?0.0001, respectively).

Conclusions

Patients with CIDP could be distinguished from controls on 3D SHINKEI.

Key points

? 3D SHINKEI could visualize brachial plexus with high spatial resolution.? CIDP patients showed increased SNR, CR, and the size of brachial plexus.? 3D SHINKEI could discriminate CIDP patients from normal subjects.

     

Multiparametric dynamic contrast-enhanced ultrasound imaging of prostate cancer

Objectives

The aim of this study is to improve the accuracy of dynamic contrast-enhanced ultrasound (DCE-US) for prostate cancer (PCa) localization by means of a multiparametric approach.

Materials and Methods

Thirteen different parameters related to either perfusion or dispersion were extracted pixel-by-pixel from 45 DCE-US recordings in 19 patients referred for radical prostatectomy. Multiparametric maps were retrospectively produced using a Gaussian mixture model algorithm. These were subsequently evaluated on their pixel-wise performance in classifying 43 benign and 42 malignant histopathologically confirmed regions of interest, using a prostate-based leave-one-out procedure.

Results

The combination of the spatiotemporal correlation (r), mean transit time (μ), curve skewness (κ), and peak time (PT) yielded an accuracy of 81%?±?11%, which was higher than the best performing single parameters: r (73%), μ (72%), and wash-in time (72%). The negative predictive value increased to 83%?±?16% from 70%, 69% and 67%, respectively. Pixel inclusion based on the confidence level boosted these measures to 90% with half of the pixels excluded, but without disregarding any prostate or region.

Conclusions

Our results suggest multiparametric DCE-US analysis might be a useful diagnostic tool for PCa, possibly supporting future targeting of biopsies or therapy. Application in other types of cancer can also be foreseen.

Key points

? DCE-US can be used to extract both perfusion and dispersion-related parameters.? Multiparametric DCE-US performs better in detecting PCa than single-parametric DCE-US.? Multiparametric DCE-US might become a useful tool for PCa localization.

     

Doubling time of thymic epithelial tumours on CT: correlation with histological subtype

Objectives

We retrospectively evaluated the doubling time (DT) of thymic epithelial tumours (TET) according to the histological subtype on CT.

Methods

From January 2005 to June 2016, we enrolled 53 patients who had pathologically confirmed TET and at least two CT scans. Tumour size was measured using a two-dimensional method, and the DT was calculated. DTs were compared among histological subtypes, and factors associated with rapid tumour growth (DT <180 days) were assessed.

Results

In 42 of the 53 patients (79.2%) the tumours showed interval growth (>2 mm) during follow-up. The median DT for all tumours was 400 days (range 48–1,964 days). There were no significant differences in DT in relation to histological subtype (p?=?0.177). When TETs were recategorized into three groups, i.e. low-risk thymomas (types A, AB, B1), high-risk thymomas (types B2, B3), and thymic carcinoma, DT was significantly different among the groups (median DT 436, 381 and 189 days, respectively; p?=?0.031). Histological subtype (type B3 and thymic carcinoma) was the single independent predictor of rapid tumour growth.

Conclusions

The majority of TETs grew during follow-up with variable and relatively slow growth rates. Histological features of aggressive behaviour significantly correlated with a decreased DT and rapid growth.

Key points

? The majority of thymic epithelial tumours grew during follow-up (79.2%, 42/53).? Doubling times of thymic epithelial tumours were highly variable (median 400 days).? Histological features of aggressive behaviour significantly correlated with a decreased doubling time.

     

Effect of microbubble-enhanced ultrasound on percutaneous ethanol ablation of rat walker-256 tumour

Objectives

Percutaneous ethanol ablation (PEA) is an effective method for treating small liver cancer. Microbubble-enhanced ultrasound (MEUS) can potentially promote PEA by disrupting the tumour’s circulation. In this study, treatment combining MEUS and PEA was performed to find any synergistic effects in tumour ablation.

Methods

Ten rats bearing subcutaneous Walker-256 tumours were treated by MEUS combined with PEA. The other 18 tumour-bearing rats that were treated by MEUS or PEA served as the controls. MEUS was conducted by therapeutic ultrasound (TUS) and microbubble injection. TUS was operated at a frequency of 831 KHz with a pressure amplitude of 4.3 MPa. Tumour blood perfusion was assessed by contrast-enhanced ultrasound (CEUS), and the tumour necrosis rate was determined by histological examination.

Results

CEUS showed that the tumour blood perfusion almost vanished in all of the MEUS-treated tumours. The contrast peak intensity dropped 84.8 % in the MEUS?+?PEA-treated tumours when compared to 46.3 % (p?<?0.05) in the PEA-treated tumours 24 h after treatment. The tumour necrosis rate of the combination therapy was 97.50 %, which is much higher than that of the MEUS- (66.2 %) and PEA-treated (81.0 %) tumours.

Conclusion

PEA combined with MEUS can induce a much more complete tumour necrosis.

Key Points

? This experiment demonstrated a novel method for enhancing percutaneous ethanol ablation. ? Microbubble-enhanced therapeutic ultrasound is capable of disrupting tumour circulation. ? Combined therapy of MEUS and PEA can induce more complete necrosis of tumours.

     

Diffusion-weighted imaging versus contrast-enhanced MR imaging for the differentiation of renal oncocytomas and chromophobe renal cell carcinomas

Objectives

To compare the performance of diffusion-weighted imaging (DWI) with that of contrast-enhanced MRI in differentiating renal oncocytomas from chromophobe renal cell carcinomas (RCCs).

Methods

We recruited 48 patients with histopathologically confirmed renal oncocytomas (n=16) and chromophobe RCCs (n=32). All patients underwent preoperative DWI and contrast-enhanced MRI. Apparent diffusion coefficient (ADC) and signal intensity were measured in each patient. ADC ratio and percentage of signal intensity change were calculated.

Results

Mean ADC values for renal oncoctytomas were significantly higher than those for chromophobe RCCs (1.59±0.21 vs. 1.09±0.29× 10^?3 mm²/s, p < 0.001). Area under the ROC curve, sensitivity and specificity were 0.931, 87.5% and 84.4%, respectively, for ADC measurement of DW imaging; 0.825, 87.5% and 75%, respectively, for enhancement ratio (p > 0.05). Adding ADC values to the enhancement ratios in the ROC, analysis to differentiate renal oncocytoma from chromophobe RCCs increased specificity from 75 to 87.5% at 87.5% sensitivity without significantly increasing the AUC (0.930).

Conclusions

Both DWI and contrast-enhanced MRI may assist in differentiating renal oncocytomas from chromophobe RCCs, with DWI showing higher diagnostic value. The combination of the two parameters could potentially provide better performance in distinguishing these two tumours.

Key Points

? ADC values can assist in differentiating renal oncocytomas from chromophobe RCCs. ? DW imaging possesses better specificity than does contrast-enhanced MR imaging. ? Combining the two parameters provides higher specificity regarding the differential diagnosis.

     

CT spectral imaging for monitoring the therapeutic efficacy of VEGF receptor kinase inhibitor AG-013736 in rabbit VX2 liver tumours

Purpose

The aim of this study was to evaluate the value of computed tomography (CT) spectral imaging in assessing the therapeutic efficacy of a vascular endothelial growth factor (VEGF) receptor inhibitor AG-013736 in rabbit VX2 liver tumours.

Methods

Twenty-three VX2 liver tumour–bearing rabbits were scanned with CT in spectral imaging mode during the arterial phase (AP) and portal phase (PP). The iodine concentrations(ICs)of tumours normalized to aorta (nICs) at different time points (baseline, 2, 4, 7, 10, and 14 days after treatment) were compared within the treated group (n?=?17) as well as between the control (n?=?6) and treated groups. Correlations between the tumour size, necrotic fraction (NF), microvessel density (MVD), and nICs were analysed.

Results

The change of nICs relative to baseline in the treated group was lower compared to the control group. A greater decrease in the nIC of a tumour at 2 days was positively correlated with a smaller increase in tumour size at 14 days (P?<?0.05 for both). The tumour nIC values in AP and PP had correlations with MVD (r?=?0.71 and 0.52) and NF (r?=?-0.54 and -0.51) (P?<?0.05 for all).

Conclusions

CT spectral imaging allows for the evaluation and early prediction of tumour response to AG-013736.

Key Points

? AG-013736 treatment response was evaluated by CT in a rabbit tumour model.? CT spectral imaging allows for the early treatment monitoring of targeted anti-tumour therapies.? Spectral CT findings correlated with vascular changes after anti-tumour therapies.? Spectral CT is a promising method for assessing clinical treatment response.