Relative apparent diffusion coefficient: Determination of reference site and validation of benefit for detecting metastatic lymph nodes in uterine cervical cancer

Purpose

To determine the reference site for relative apparent diffusion coefficient (rADC) and to evaluate the benefit of rADC for detecting metastatic lymph nodes in uterine cervical cancer.

Materials and Methods

Two observers independently measured ADCs in the spleen, liver, renal cortex, lumbar spine, lumbar spinal cord, and gluteus maximus on diffusion‐weighted images (b value, 0 and 1000 mm/sec²) in 50 patients. The reference site for rADC was determined using the intra‐ and interobserver coefficient of variation (CV) of ADC in these organs. rADC was calculated by ADC_lesion/ADC_{reference site}. The benefit of rADC over ADC was validated by comparing the area under the receiver operating curve for identifying metastatic lymph nodes in uterine cervical cancer in 130 patients.

Results

The renal cortex was determined to be the reference site for rADC, as its CVs (intraobserver, 5%–7%; interobserver, 5%) were less than those of the other organs (P < 0.05). The ADC and rADC of metastatic lymph nodes (n = 29, ADC, 0.7483 × 10^?3 mm²/sec; rADC, 0.3832) were less than those of nonmetastatic lymph nodes (n = 229, ADC, 0.9960 × 10^?3 mm²/sec; rADC, 0.5383) (P < 0.05). The area under the receiver operating characteristics curve for differentiating metastatic from nonmetastatic lymph nodes was greater for rADC (0.914; 95% confidence interval [CI], 0.872–0.945) than for ADC (0.872; 95% CI, 0.825–0.910) (P = 0.007).

Conclusion

The renal cortex is an appropriate reference site for rADC and rADC may improve the accuracy for diagnosing metastatic lymph nodes in uterine cervical cancer. J. Magn. Reson. Imaging 2009;29:383–390. © 2009 Wiley‐Liss, Inc.

     

Correlation of apparent diffusion coefficient values and peritumoral edema with pathologic biomarkers in patients with breast cancer

PurposeTo investigate the relationship between breast cancer imaging features on magnetic resonance imaging (MRI) and histopathological characteristics.Methods and materialsWe prospectively enrolled 46 patients who underwent 1.5-T MRI with 68 breast malignant lesions from 2017 until 2019. Peritumoral edema was determined based on visual assessment on T2 weighted imaging. Lesions were categorized into two groups: A: with edema (48 lesions) and B: without edema (20 lesions).ResultsThe tumor size was not different among two groups but multifocal-multicentric lesions were more common in the group A (70% vs. 35%). The axillary lymph nodes are most involved in group A. ER and PR positive lesions were more common in group B (90% vs. 56.3%) but in the group A, HER2 positive lesions were found to be more common (31.3% vs. 15%). The mean ADC value in tumors and peritumoral regions were lower (0.97 × 10⁻³ mm²/s, P = 0.023) and higher (1.85 × 10⁻³ mm²/s, P < 0.0001) in group A, respectively. Peritumoral ADC value was significantly higher in HER2-positive group.ConclusionBreast carcinomas with peritumoral edema were found to be more multifocal-multicentric, with higher prevalence of axillary lymph node involvement, more HER 2-positive, with lower prevalence of ER/PR-positive, lower tumoral ADC and higher peritumoral ADC values.     

Respiratory gated diffusion-weighted imaging of the liver: value of apparent diffusion coefficient measurements in the differentiation between most commonly encountered benign and malignant focal liver lesions

The purpose of this study was to measure apparent diffusion coefficient values of normal liver parenchyma and focal liver lesions utilizing a respiratory gated diffusion sequence with multiple b-values and to investigate whether apparent diffusion coefficient (ADC) measurements may be utilized to characterize and differentiate between malignant and benign focal hepatic lesions. Thirty-eight consecutive patients underwent MRI of the liver including diffusion-weighted imaging (DWI). A single-shot echo planar imaging sequence was applied in coronal orientation with multiple b-values (0, 50, 500, 1,000 s/mm²) and respiratory gating. ADC values were recorded on corresponding maps utilizing region of interest measurements in patients with benign (group A), malignant (group B) focal lesions and liver parenchyma (group C). Statistical analysis was applied to check whether differences in mean ADC values were significant (p<0.05). No focal lesions were detected in 11 patients, with a mean ADC value (CI 95%) of liver parenchyma 1.25×10⁻³ mm²/s (1.21×10⁻³ mm²/s−1.29×10⁻³ mm²/s). Differences in mean ADC of liver parenchyma between group A and B were not significant (p=0.054, 1.30×10⁻³ mm²/s and 1.31×10⁻³ mm²/s, respectively). Mean ADC value (95% CI) of 22 benign lesions found in 18 patients was 2.55×10⁻³ mm²/s (2.35×10⁻³ mm²/s−2.74×10⁻³ mm²/s), while the mean ADC value (95% CI) of 16 malignant lesions recorded in 9 patients was 1.04×10⁻³ mm²/s (0.9×10⁻³ mm²/s−1.17×10⁻³ mm²/s). The difference between mean ADC values of benign and malignant focal lesions was statistically significant (p<0.0001). Respiratory gated diffusion-weighted imaging in the liver is technically feasible. Apparent diffusion coefficient measurements can be useful in differentiating malignant from benign focal liver lesions.     

Apparent diffusion coefficient values of cryptorchid testes and malignant transformation of cryptorchidism (MTC) (seminoma) in postpubertal patients

Objectives:Diffusion-weighted imaging signal contrast can be quantified by apparent diffusion coefficient (ADC) maps, which reflect the diffusion properties of the examined tissue and are helpful for identifying pathology. To determine ADC values of cryptorchid testes in post-pubertal patients and assess performance for characterizing cryptorchid testes.Methods:The medical records from 35 patients with unilateral scrotal vacuity were retrospectively reviewed. Data were analyzed in three groups: Group A, normal testes (i.e. the contralateral testes of the patients with cryptorchidism or MTC); Group B, cryptorchid testes; and Group C, malignant transformation of cryptorchidism (MTC) (seminoma). DWI used b-values of 0 and 800 s/mm². Mean ADC values were compared using the independent samples t-test. The ability of ADC values was assessed using receiver operating characteristic curve analysis. The sensitivity, specificity, and accuracy were calculated.Results:Mean ADC values for normal testes, cryptorchid testes, and MTC were 1.18 ± 0.18×10⁻³ mm²/s, 1.82 ± 0.40×10⁻³ mm²/s, and 0.80 ± 0.06×10⁻³ mm²/s, respectively. There were statistically significant differences in mean ADC values between normal testes and cryptorchid testes or MTC (p < 0.001). The cut-off ADC value for differentiating normal testes from cryptorchid testes was 1.47 × 10⁻³ mm²/s. The sensitivity, specificity, and accuracy were 88%, 91%, and 90%, respectively. The cut-off ADC value for differentiating normal testes from MTC was 1.22 × 10⁻³ mm²/s. The sensitivity, specificity, and accuracy were 100%, 31%, and 43%, respectively.Conclusion:ADC values of cryptorchid testes may be used to inform clinical decision-making and also monitor testicular function in patients who retain undescended testicles or post-operatively.Advances in knowledge:Mean ADC values of cryptorchidism and MTC (seminoma) were used to reflect their pathological features.     

Early Detection of Therapeutic Response to Hepatic Arterial Infusion Chemotherapy of Liver Metastases from Colorectal Cancer Using Diffusion-Weighted MR Imaging

The purpose of this study was to investigate whether diffusion-weighted magnetic resonance imaging (DWI) is useful for early detection of the response of hepatic colorectal metastases to hepatic arterial infusion chemotherapy (HAIC) with 5-fluorouracil (5-FU). The subjects were 12 patients with hepatic colorectal metastases. The indwelling catheter for HAIC was placed in the hepatic artery, and 1000 mg/m² 5-FU was given repeatedly once a week. DWI was performed before and 9 days after HAIC. The minimum and mean apparent diffusion coefficient (ADC) values (minADC and meanADC) were measured. The relative change in ADC values (%ADC) and the relative change in tumor size on follow-up CT after 3 months (reduction ratio) were determined. Liver metastases were divided into two groups, responder and nonresponder. The correlation between %ADC and reduction ratio was determined, and %ADC was compared between the two groups. Eleven patients successfully completed HAIC over the 3-month period; 48 metastatic lesions were evaluated. Positive correlations were observed for relative change between %minADC and reduction ratio (r = 0.709) and between %meanADC and reduction ratio (r = 0.536). Both %minADC and %meanADC were significantly greater in the responder group than in the nonresponder group. With the threshold determined as < 3.5%, the receiver-operating curve analysis showed higher sensitivity and specificity values for %minADC (100% and 92.6%, respectively) than for %meanADC (66.7% and 74.1%, respectively). In conclusion, the relative change in minimum ADC values on DWI may be useful for early detection of the response of liver metastases to HAIC with 5-FU.     

Evaluation of treatment response of chemoembolization in hepatocellular carcinoma with diffusion-weighted imaging on 3.0-T MR imaging

PurposeTo assess the treatment response of hepatocellular carcinoma (HCC) after transarterial chemoembolization with diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance (MR) imaging with a 3-T system.Materials and MethodsBetween February 2010 and November 2010, 74 patients were treated with chemoembolization in our interventional radiology unit. Twenty-two patients (29%) who had liver MR imaging including diffusion and dynamic contrast-enhanced MR imaging on a 3-T system before and after transarterial chemoembolization were evaluated retrospectively. Tumor size, arterial enhancement, venous washout, and apparent diffusion coefficient (ADC) values of lesions, peritumoral parenchyma, normal liver parenchyma, and spleen were recorded before and after treatment. The significance of differences between ADC values of responding and nonresponding lesions was calculated.ResultsThe study included 77 HCC lesions (mean diameter, 31.4 mm) in 20 patients. There was no significant reduction in mean tumor diameter after treatment. Reduction in tumor enhancement in the arterial phase was statistically significant (P = .01). Tumor ADC value increased from 1.10 × 10^?3 mm²/s to 1.27 × 10^?3 mm²/s after treatment (P < .01), whereas the ADC values for liver and spleen remained unchanged. ADC values from cellular parts of the tumor and necrotic areas also increased after treatment. However, pretreatment ADC values were not reliable to identify responding lesions according to the results of receiver operating characteristic analysis.ConclusionsAfter transarterial chemoembolization, responding HCC lesions exhibited decreases in arterial enhancement and increases in ADC values in cellular and necrotic areas. Pretreatment ADC values were not predictive of response to chemoembolization.     

Diffusion MRI for rectal cancer staging: ADC measurements before and after ultrasonographic gel lumen distension

ObjectivesTo compare Apparent Diffusion Coefficient (ADC) measurements in rectal neoplastic lesions before and after lumen distension obtained with sonography transmission gel.MethodsFrom January 2014 to July 2016, 25 patients (average age 63.7, range 41–85, 18 males) were studied for pre-treatment rectal cancer staging using a 1.5 T MRI. Diffusion MRI was obtained using echo-planar imaging with b = 800 value; all patients were studied acquiring diffusion sequences with and without rectal lumen distension obtained using sonography transmission gel. In both diffusion sequences, two blinded readers calculated border ADC values and small ADC values, drawing regions of interest respectively along tumour borders and far from tumour borders. Mean ADC values among readers − for each type of ADC measurement − were compared using Wilcoxon matched pairs signed rank test. Correlation was assessed using Pearson analysis.ResultsBorder ADC mean value for diffusion MR sequences without endorectal contrast was 1.122 mm²/sec, with 95% Confidence Interval (CI) = 1.02–1.22; using gel lumen distension, higher border ADC mean value of 1.269 mm²/s (95% CI = 1.16–1.38) was obtained. Wilcoxon matched pairs signed rank test revealed statistical difference (p < 0.01); a strong Pearson correlation was reported, with r value of 0.69. Small-ADC mean value was 1.038 mm²/s (95% CI = 0.91–1.16) for diffusion sequences acquired without endorectal distension and 1.127 mm²/s (95% CI = 0.98–1.27) for diffusion sequences obtained after endorectal gel lumen distension. Wilcoxon analysis did not show statistical difference (p = 0.13). A very strong positive correlation was observed, with r value of 0.81.ConclusionsADC measurements are slightly higher using endorectal sonographic transmission gel; ROI should be traced far from tumour borders, to minimize gel filled-pixel along the interface between lumen and lesion. Further studies are needed to investigate better reliability of ADC in rectal cancer MRI using sonographic gel intraluminal distension.     

Diffusion-Weighted MRI of Malignant versus Benign Portal Vein Thrombosis

ObjectiveTo validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis.ResultsThe mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10^-3 mm²/sec and 0.92 ± 0.25 × 10^-3 mm²/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10^-3 mm²/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively.ConclusionDue to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently.     

Role of diffusion-weighted imaging in prediction of nipple-areolar complex invasion by breast cancer

The aim of this workThe aim of this work was to estimate the role of diffusion-weighted imaging (DWI) in predicting malignant invasion of the nipple-areolar complex (NAC) by underlying breast cancer.Material and methodsThis prospective study included 70 female patients with breast cancer with a mean age of 45.8 years (range: 28–68). DWI of the breast was done for all patients. Apparent diffusion coefficient (ADC) maps were automatically constructed. The mean ADC values of NAC were independently measured by two observers who are experts in breast imaging and correlated with the results of histopathological examinations.ResultsBoth observers found a significantly lower ADC value of malignant NAC invasion (n = 18) when compared with free NAC (n = 52), with mean ADC value for malignant NAC invasion was 0.86 ± 0.35 × 10⁻³ mm²/s and 0.84 ± 0.08 × 10⁻³ mm²/s for observer one and two respectively versus mean ADC value of 1.34 ± 0.25 × 10⁻³ mm²/s and 1.4 ± 0.26 × 10⁻³ mm²/s for free NAC by observer one and two respectively (P-value =0.001). Observer one found that a cutoff ADC value of 1.05 × 0⁻³ mm²/s can predict malignant NAC invasion with 0.975 AUC, 92.8% accuracy, 94.4% sensitivity, and 92.3% specificity. Observer two found that a cutoff ADC value of 0.95 × 10⁻³ mm²/s can predict malignant NAC invasion with 0.992 AUC, 95.7% accuracy, 88.9% sensitivity, and 98.1% specificity.ConclusionDWI can predict malignant NAC invasion in patients with breast cancer.     

Diffusion-Weighted MR Imaging to Evaluate Immediate Response to Irreversible Electroporation in a Rabbit VX2 Liver Tumor Model

PurposeTo evaluate the feasibility of diffusion-weighted imaging (DWI) in magnetic resonance imaging for quantitative measurement of responses following irreversible electroporation (IRE) in a rabbit liver tumor model.Materials and MethodsTwelve rabbits underwent ultrasound-guided VX2 tumor implantation in the left medial and left lateral liver lobes. The tumors in the left medial lobe were treated with IRE, whereas those in the left lateral lobe served as internal controls. DWI was performed before and immediately after IRE. Tumors were then harvested for histopathologic staining. The apparent diffusion coefficient (ADC) and change in ADC (ΔADC) were calculated based on DWI. Tumor apoptosis index (AI) was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling. These measurements from DWI and histopathology were compared between untreated and treated tumors.ResultsThe ADC values, ΔADC, and AI showed statistically significant differences between treated and untreated tumors (P < .05 for all). ADC values were higher in treated tumors than in untreated tumors (1.08 × 10^?3 mm²/s ± 0.15 vs 0.88 × 10^?3 mm²/s ± 0.19; P = .042).ConclusionsDWI can be used to quantitatively evaluate treatment response in liver tumors immediately after IRE.     

Can pretreatment ADC values predict recurrence of bladder cancer after transurethral resection?

Objective

The aim of this retrospective study was to investigate the association between the pretreatment apparent diffusion coefficient (ADC) value and recurrence of bladder cancer after transurethral resection.

Methods

Patients with superficial bladder cancer were identified. Mean ADC values of the tumors were compared between patients with and without recurrence following trans-urethral resection. A receiver–operator characteristic curve was used for determining the optimal cutoff ADC value. Univariate and multivariate analyses were used to determine the effect of ADC values and other factors.

Results

With a mean follow-up period of 25 months, bladder cancer recurred in 14 of 44 patients (32%). The mean ADC value of tumors in patients with recurrence was lower than in those without recurrence (1.08 mm²/s vs. 1.28 × 10⁻³ mm²/s; p = 0.003). The optimal cutoff ADC value for predicting recurrence was determined to be 1.12 × 10⁻³ mm²/s. A modest and significant negative correlation was observed between the ADC values and tumor size (r = −0.436, p = 0.008). After adjustment for size and risk groups, an ADC value equal to or less than the optimal cutoff remained a significant predictor of recurrence (odds ratio 6.3, 95% CI 1.23–32.2, p = 0.027).

Conclusion

Pretreatment ADC values may be an independent predictor of bladder cancer recurrence.     

Apparent Diffusion Coefficient of Uterine Leiomyoma as a Predictor of the Potential Response to Uterine Artery Embolization

PurposeTo determine the utility of the apparent diffusion coefficient (ADC) of uterine leiomyoma for prediction of the potential response to uterine artery embolization (UAE).Materials and MethodsThis prospective study included 49 patients with uterine leiomyomas who underwent diffusion-weighted magnetic resonance (MR) imaging before UAE between May 2011 and January 2012. All patients also underwent 3-month follow-up MR imaging after UAE. Using conventional and diffusion-weighted MR imaging sequences, 72 uterine leiomyomas ≥ 3 cm were prospectively evaluated. The volume of each leiomyoma was calculated, and quantitative measurement of ADC was performed. Regression analysis was used to evaluate the relationship between ADC and volumetric response after UAE. Receiver operating characteristic curve analysis was performed to determine the sensitivity and specificity of ADC for prediction of the potential response to UAE. Interclass correlation coefficient analysis was used to assess interobserver variability between two radiologists.ResultsVolume reduction rates of leiomyomas after UAE ranged from 0.2%–89.1% (mean, 44.1%). ADC ranged from 0.559 × 10^?3 mm²/s to 1.814 × 10^?3 mm²/s (mean, 1.170 × 10^?3 mm²/s). ADC was statistically significantly related to volumetric response of leiomyomas (P = .014). Using a threshold of 1.092 × 10^?3 mm²/s, the sensitivity and specificity of ADC for prediction of > 50% volume reduction of the leiomyoma after UAE were 82.6% and 52.3%, respectively. Using a threshold of 1.023 × 10^?3 mm²/s, the sensitivity and specificity of ADC for prediction of < 30% volume reduction were 80.8% and 33.3%, respectively. The interclass correlation coefficient for measuring ADC of uterine leiomyomas between two radiologists was 0.98.ConclusionsADC of uterine leiomyomas was significantly related to the volume reduction after UAE. ADC may be useful in predicting the potential response to UAE. A high ADC of the uterine leiomyoma may be associated with a greater volume reduction after UAE.     

Role of diffusion-weighted imaging with ADC mapping and in vivo H-MR spectroscopy in thyroid nodules

Purpose

To evaluate the role of the combined techniques of apparent diffusion coefficient (ADC) generated from diffusion-weighted magnetic resonance (MR) imaging (DWI) and metabolite spectrum acquired by magnetic resonance spectroscopy (MRS) in differentiating benign from malignant thyroid nodules.

Materials and methods

Thirty-seven patients with 56 thyroid nodules were evaluated with conventional MRI (T1- & T2-WI), DWI (b value 0.500 s/mm²; ADC values were calculated for the thyroid nodules), and MRS (for the presence or absence of choline peak). The ADC values and MRS findings were correlated with the histopathological results.

Results

The mean ADC of the malignant thyroid nodules (0.89 ± 0.27 × 10⁻³ mm²/s) was significantly lower than that of the mean ADC of the benign thyroid nodules (1.85 ± 0.24 × 10⁻³ mm²/s) (p value <0.0001). ADC value of 1.5 × 10⁻³ mm²/s was used as a cut-off value for differentiation benign from malignant thyroid nodules. The sensitivity, specificity, PPV&NPV of DWI in differentiating benign from malignant thyroid nodules were 94%, 95%, 94% & 95%, respectively (Kappa test 0.84, p value <0.0001), whereas they were 94.7%, 89.2%, 81.8% & 97.1% (Kappa test 0.8, p value <0.0001) with MRS, and 96%, 100%, 100% & 97% (Kappa test 0.96, p value <0.0001) with both DWI and MRS.

Conclusion

Both DWI and MRS are useful diagnostic modalities for characterization and differentiation between benign and malignant thyroid nodules. Our preliminary results showed that combination of DWI with calculated ADC values and metabolite spectrum acquired by MRS add more information to MRI and should be considered as an additional and complementary tool to conventional MRI for differentiating benign from malignant thyroid nodules.     

Is it possible to differentiate between hydatid and simple cysts in the liver by means of diffusion-weighted magnetic resonance imaging?

ObjectiveOur aim was to evaluate the contribution of diffusion-weighted imaging to the differentiation of hydatid cysts (HCs) from the simple cysts and to the identification of the HC subtypes.Materials and methodsA total of 37 patients were included in this retrospective study. Fifty of these patients had diagnosed liver cysts (28 HCs and 22 simple cysts) of at least 1 cm in size. All of the cysts were examined with sonography and magnetic resonance imaging, and the HCs were classified according to the World Health Organization criteria.ResultsTwenty-eight of the total 50 cysts were HCs, and 22 were simple cysts. When the apparent diffusion coefficient (ADC) values of all HCs were compared with the ADC values of the simple cysts, a statistically significant relationship was found (P=.001). The optimal ADC threshold value was established as 2.5 s/mm². The sensitivity, specificity, positive predictive value, negative predictive value and accuracy rates were 60%, 95%, 94%, 65% and 76%, respectively.ConclusionDiffusion-weighted imaging–magnetic resonance imaging is a considerably helpful technique for differentiating between HCs and simple cysts and for differentiating between HC subtypes.     

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging for Differentiation Between Parotid Neoplasms

PurposeThis study was designed to evaluate the role of multiparametric magnetic resonance imaging (MRI) for differentiation of parotid gland neoplasms.MethodsProspective study was conducted upon 52 consecutive patients (30 men, 22 women; aged 24–78 years; mean, 51 years) with parotid tumours that underwent multiparametric MRI using combined static MRI, dynamic contrast enhanced (DCE) MRI, and diffusion-weighted imaging (DWI). The static MRI parameter, time signal intensity curves (TIC) derived from DCE-MRI, and apparent diffusion coefficient (ADC) values of parotid tumours were correlated with histopathological findings.ResultsStatic MRI revealed a significant difference between both benign and malignant lesions in regards to margin definition (P < .001) and T2 hypointensity (P < .013), with a diagnostic accuracy 95% and 78.33% respectively. Study of the TIC type on DCE-MRI revealed statistically significant difference between benign and malignant lesions (P < .001) and diagnostic accuracy 96.55%. There was no statistically significant difference (P = .181) between the ADC values of benign and malignant lesions. ROC curve analysis revealed that by using ADC cut-off value of 1 × 10^?3 mm²/s had accuracy of 84.62% respectively for differentiating Warthin from malignant tumours that could be modified to higher value (94.28%) by excluding lymphoma from malignant lesions. By using cutoff value of 1.3 × 10^?3 mm²/s to differentiate pleomorphic adenoma from malignancy, ROC curve analysis had high accuracy of 97.06%.ConclusionMultiparametric MRI can be used for differentiation of malignant from benign parotid tumours and characterization of some benign parotid tumours.     

Aortic valve and left ventricular outflow tract calcium volume and distribution in transcatheter aortic valve replacement: Influence on the risk of significant paravalvular regurgitation

ObjectivesWe sought to determine the impact of aortic root calcium on the risk of significant paravalvular regurgitation (sPAR) in transcatheter aortic valve replacement (TAVR).MethodsIn 302 consecutive patients from 3 centers, aortic root calcium was quantified volumetrically on pre-TAVR multidetector computed tomography (MDCT) in three regions: 1) the aortic valve region, 2) the overall left ventricular outflow tract (LVOT) and 3) the upper LVOT. Transcathether heart valve (THV) oversizing was calculated as (THV nominal area/MDCT annular area−1) × 100. The study endpoint sPAR was a composite of post-dilatation (PD) and PAR > mild.ResultssPAR occurred in 15% (46/302) of patients. Upper LVOT calcium volume was more predictive of sPAR than overall LVOT calcium volume, with an area under the receiver operating curve (AUC) (95% confidence interval [CI]) of 0.80 (0.67–0.89) vs. 0.60 (0.51–0.70); p = 0.0001. The optimal cut-off calcium volume thresholds determined from receiver operating curves were 21 mm³ and 30 mm³ for upper LVOT and overall LVOT calcium, respectively. Upper LVOT calcium ≥ 21 mm³, but not overall LVOT calcium ≥ 30 mm³, independently predicted sPAR, odds ratio (95%CI): 9.5 (4.1–22.3) vs 1.6 (0.6–2.7). Upper LVOT calcium was more predictive of sPAR in patients with THV oversizing ≥ 13% compared to patients with THV oversizing <13%, AUC (95% CI): 0.83 (0.72–0.93) vs. 0.67 (0.51–0.74); p < 0.0001.ConclusionsUpper LVOT calcium predicts more-than-mild paravalvular regurgitation following TAVR or the need for postdilatation. Upper LVOT calcium is most predictive of paravalvular regurgitation in the event of THV oversizing ≥ 13%.     

Diffusion-weighted imaging of focal renal lesions: a meta-analysis

Objectives

Contrast-enhanced MRI can only distinguish to a limited extent between malignant and benign focal renal lesions. The aim of this meta-analysis is to review renal diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values for different renal lesions that can be applied in clinical practice.

Methods

A PubMed search was performed to identify relevant articles published 2004–2011 on renal DWI of focal renal lesions. ADC values were extracted by lesion type to determine whether benign or malignant. The data table was finalised in a consensus read. ADC values were evaluated statistically using meta-regression based on a linear mixed model. Two-sided P value <5 % indicated statistical significance.

Results

The meta-analysis is based on 17 studies with 764 patients. Renal cell carcinomas have significant lower ADC values than benign tissue (1.61?±?0.08?×?10^-3 mm²/s vs 2.10?±?0.09?×?10^-3 mm²/s; P?<?0.0001). Uroepithelial malignancies can be differentiated by lowest ADC values (1.30?±?0.11?×?10^-3 mm²/s). There is a significant difference between ADC values of renal cell carcinomas and oncocytomas (1.61?±?0.08?×?10^-3 mm²/s vs 2.00?±?0.08?×?10^-3 mm²/s; P?<?0.0001).

Conclusions

Evaluation of ADC values can help to determine between benign and malignant lesions in general but also seems able to differentiate oncocytomas from malignant tumours, hence potentially reducing the number of unnecessarily performed nephrectomies.

Key Points

? This meta-analysis assesses the role of diffusion-weighted MRI in renal lesions. ? ADC values obtained by DW MRI have been compared for different renal lesions. ? ADC values can help distinguish between benign and malignant tumours. ? Differentiating oncocytomas from malignant tumours can potentially reduce inappropriate nephrectomies.     

Evaluation of Extramural Venous Invasion by Diffusion-Weighted Magnetic Resonance Imaging and Computed Tomography in Rectal Adenocarcinoma

PurposeThe aim of this study is to evaluate the diagnostic contribution of diffusion-weighted magnetic resonance imaging (MRI) and computed tomography (CT) to distinguish extramural venous invasion (EMVI) in rectal adenocarcinoma.Materials and MethodsFifty-eight patients who had been diagnosed with rectal adenocarcinoma (30 patients with EMVI and 28 patients without EMVI) were enrolled in the study. Apparent diffusion coefficient (ADC) values of the tumour and the EMVI (+) vein, the lengths of the tumours were measured on MRI. The diameters of the superior rectal vein (SRV)-inferior mesenteric vein (IMV) and distant metastatic spread were evaluated on CT. The ability of these findings to detect EMVI was assessed using receiver operating characteristic (ROC) analysis. Pathology was accepted as the reference test for EMVI.ResultsMean diameters of the SRV (4.9 ± 0.9 mm vs 3.7 ± 0.8 mm) and IMV (6.9 ± 0.8 mm vs 5.4 ± 0.9 mm) were significantly larger (P < .001) and tumour ADC values were significantly lower (0.926 ± 0.281 × 10⁻³ mm²/s vs 1.026 ± 0.246 × 10⁻³ mm²/s; P = .032) in EMVI (+) patients. Diameters of 3.95 mm for the SRV (area under the curve [AUC] ± standard error [SE]: 0.851 ± 0.051, P < .001, sensitivity: 93.3%, specificity: 67.9%) and 5.95 mm for the IMV (AUC ± SE: 0.893 ± 0.040, P < .001, sensitivity: 93.3%, specificity: 71.4%) and an ADC value of 0.929 × 10⁻³ mm²/s (AUC ± SE: 0.664 ± 0.072, P = .032 sensitivity: 76.7%, specificity: 57.1%) were found to be cutoff values, determined by ROC analysis, for detection of EMVI. Distant metastases were significantly more prevalent in EMVI (+) patients (P < .001).ConclusionThe measurement of ADC values and SRV-IMV diameters seems to have contribution for diagnosis of EMVI in rectal adenocarcinoma. EMVI (+) patients appear to have higher risks of distant metastases at diagnosis.     

Predictive value of pre-treatment apparent diffusion coefficient (ADC) in radio-chemiotherapy treated head and neck squamous cell carcinoma

Objective

This study aimed at evaluating the role of “baseline” apparent diffusion coefficent (ADC), in patients affected by head and neck cancer treated with radio-chemotherapy, as a potential marker of response to therapy.

Methods

Fifty-seven patients underwent pretreatment ADC maps. Minimum, maximum, and medium ADC were computed. Age, dose, treatment time, and ADC values were compared between the two groups (Group 1: local control; Group 2: relapse/persistence of disease) using the Student t test two-tailed unpaired. Two-tailed Fischer exact test was used to compare T stage, N stage, grading and type of treatment between two groups. We have analyzed the receiver operating characteristic (ROC) of statistically significant variables.

Results

In patients with local control, values of pre-treatment medium and minimum ADC were lower than ADC values of patients with persistent or recurrent disease, with values, respectively, of 0.83 ± 0.02 × 10^–3 mm²/s and 0.59 ± 0.02 × 10^–3 mm²/s (vs 0.94 ± 0.05 × 10^–3 mm²/s and 0.70 ± 0.05 × 10^–3 mm²/s). ROC curve analysis displayed statistical significance as regarding the medium ADC value, showing a sensitivity of 50% and a specificity of 84.8%. ROC analysis of the values minimum ADC showed a sensitivity of 42.9% and specificity of 87.9%.

Conclusion

The value of the ADC pre-treatment of patients with local control of the disease is lower than that of patients with persistent disease or recurrence.

     

Diffusion-Weighted Imaging for Differentiation of Biliary Atresia and Grading of Hepatic Fibrosis in Infants with Cholestasis

ObjectiveTo determine whether the values of hepatic apparent diffusion coefficient (ADC) can differentiate biliary atresia (BA) from non-BA or be correlated with the grade of hepatic fibrosis in infants with cholestasis.Materials and MethodsThis retrospective cohort study included infants who received liver MRI examinations to evaluate cholestasis from July 2009 to October 2017. Liver ADC, ADC ratio of liver/spleen, aspartate aminotransferase to platelet ratio index (APRI), and spleen size were compared between the BA and non-BA groups. The diagnostic performances of all parameters for significant fibrosis (F3–4) were obtained by receiver-operating characteristics (ROCs) curve analysis.ResultsAltogether, 227 infants (98 males and 129 females, mean age = 57.2 ± 36.3 days) including 125 BA patients were analyzed. The absolute ADC difference between two reviewers was 0.10 mm²/s for both liver and spleen. Liver ADC value was specific (80.4%) and ADC ratio was sensitive (88.0%) for the diagnosis of BA with comparable performance. There were 33 patients with F0, 15 with F1, 71 with F2, 35 with F3, and 11 with F4. All four parameters of APRI (τ = 0.296), spleen size (τ = 0.312), liver ADC (τ = −0.206), and ADC ratio (τ = −0.288) showed significant correlation with fibrosis grade (all, p < 0.001). The cutoff values for significant fibrosis (F3–4) were 0.783 for APRI (area under the ROC curve [AUC], 0.721), 5.9 cm for spleen size (AUC, 0.719), 1.044 × 10⁻³ mm²/s for liver ADC (AUC, 0.673), and 1.22 for ADC ratio (AUC, 0.651).ConclusionLiver ADC values and ADC ratio of liver/spleen showed limited additional diagnostic performance for differentiating BA from non-BA and predicting significant hepatic fibrosis in infants with cholestasis.