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.     

Value of DW-MRI ADC quantification of colonic wall lesions in differentiation of inflammatory bowel disease and colorectal carcinoma

Purpose

The purpose of our study was to assess the efficiency of diffusion-weighted magnetic resonance imaging (DW-MRI) and the quantification of apparent diffusion coefficient (ADC) values in differentiating colorectal carcinoma from colonic inflammatory bowel disease (IBD) in cases with isolated colonic wall lesions and uncertain clinical and radiologic diagnostic criteria.

Methods

The study comprised 58 patients with segmental or focal isolated colonic wall thickening. All lacked satisfactory clinical–radiological findings for etiology determination. The mean ADC values of the thickened colonic walls were retrospectively compared with final histopathologic diagnoses. Receiver operating characteristic (ROC) curve analysis was used to determine the ADC cutoff value for differentiation.

Results

Mean ADC value in the colorectal carcinoma group was significantly lower than that in the IBD group: n = 27, 1.02 ± 0.26 × 10^?3 mm²/s; and n = 31, 1.53 ± 0.19 × 10^?3 mm²/s, respectively (P < 0.001). Cutoff ADC value for differentiating colorectal carcinoma from IBD was calculated as 1.39 × 10^?3 mm²/s, with 83.9 % sensitivity and 85.2 % specificity.

Conclusion

ADC measurement of the involved colonic wall segments with DW-MRI has the potential to differentiate isolated colonic IBD from colorectal carcinoma in cases in which clinical–radiologic findings are insufficient for a definitive diagnosis.     

Detection of invasive components in cases of breast ductal carcinoma in situ on biopsy by using apparent diffusion coefficient MR parameters

Objectives

To evaluate whether apparent diffusion coefficient (ADC) parameters could identify invasive components in cases with ductal carcinoma in situ (DCIS) diagnosed by biopsy.

Methods

This retrospective study was approved by the institutional review board and the requirement to obtain informed consent was waived. Sixty-nine consecutive women with 70 lesions diagnosed with DCIS by biopsy underwent breast magnetic resonance (MR) imaging. Multiple regions of interest were placed (as many as possible) within the lesion on ADC maps. The minimum ADC values and the ADC difference values obtained as the difference between minimum and maximum ADCs were evaluated.

Results

Surgical specimens revealed 51 lesions with pure DCIS and the remaining 19 lesions with DCIS with invasive components (DCIS-IC). The minimum ADC value for DCIS-IC (0.99?±?0.04?×?10^?3 mm²/s) was significantly lower than that of pure DCIS (1.15?±?0.03?×?10^?3 mm²/s) (P??=??0.0037). The ADC difference value for DCIS-IC (0.38?±?0.05?×?10^?3 mm²/s) was significantly higher than that of pure DCIS (0.17?±?0.03?×?10^?3 mm²/s). ROC curve analysis for differentiating DCIS-IC from pure DCIS revealed that the area under the curve was 0.71 for minimum ADC value and 0.77 for ADC difference value.

Conclusions

The minimum ADC values and ADC difference values could suggest the presence of invasive components.

Key Points

? Identification of invasive components in DCIS before treatment is clinically important. ? Diffusion-weighted MR imaging can help lesion assessment in breast cancer. ? The minimum ADC value may suggest the presence of an invasive component in DCIS. ? The ADC difference value also suggests the presence of an invasive component in DCIS. ? Preoperative evaluation of diffusion-weighted MR imaging may help surgical planning for DCIS.     

Diffusion-weighted MRI in pretreatment prediction of response to neoadjuvant chemotherapy in patients with breast cancer

Purpose

To evaluate the accuracy of the apparent diffusion coefficient (ADC) provided by diffusion-weighted imaging (DWI) in predicting the response to neoadjuvant chemotherapy (NACT) at baseline in patients according to their breast tumour phenotypes.

Materials & methods

This retrospective study was approved by our institutional review board. One hundred eighteen consecutive women with locally advanced breast cancer who had undergone NACT followed by breast surgery were included. DWI was performed at 1.5 T less than 2 weeks before NACT. We studied the correlation between pretreatment ADC and response in pathology after surgery according to immunohistochemical features and intrinsic subtypes (luminal A, luminal B, HER2-enriched, and triple-negative tumours).

Results

After surgery, the pathologist recognized 24 complete responders (CRps) and 94 non-complete responders (NCRps). No difference was identified between the pretreatment ADCs of the CRp and NCRp patients. There were differences in pretreatment ADCs among the luminal A (1.001 ± 0.143?×?10^?3 mm²/s), luminal B (0.983 ± 0.150?×?10^?3 mm²/s), HER2-enriched (1.132 ± 0.216?×?10^?3 mm²/s), and triple-negative (1.168 ± 0.245?×?10^?3 mm²/s; P?=?0.0003) tumour subtypes. In triple-negative tumours, the pretreatment ADC was higher in NCRp (1.060 ± 0.143?×?10^?3 mm²/s) than in CRp patients (1.227 ± 0.271?×?10^?3 mm²/s; P?=?0.047).

Conclusion

Pretreatment ADC can predict the response of breast cancer to NACT if tumour subtypes are considered. Key Points ? Apparent diffusion coefficient helps clinicians to assess patients with breast cancer. ? Pretreatment ADC is related to tumour grade and hormone receptor status. ? Pretreatment ADC is lower in luminal A and B than in triple-negative tumours. ? Pretreatment ADC is higher in complete than in non-complete responders to neoadjuvant chemotherapy.     

Quantitative analysis of diffusion-weighted magnetic resonance imaging in malignant breast lesions using different b value combinations

Objectives

To explore how apparent diffusion coefficients (ADCs) in malignant breast lesions are affected by selection of b values in the monoexponential model and to compare ADCs with diffusion coefficients (Ds) obtained from the biexponential model.

Methods

Twenty-four women (mean age 51.3 years) with locally advanced breast cancer were included in this study. Pre-treatment diffusion-weighted magnetic resonance imaging was performed using a 1.5-T system with b values of 0, 50, 100, 250 and 800 s/mm². Thirteen different b value combinations were used to derive individual monoexponential ADC maps. All b values were used in the biexponential model.

Results

Median ADC (including all b values) and D were 1.04?×?10^-3?mm²/s (range 0.82–1.61?×?10^-3?mm²/s) and 0.84?×?10^-3?mm²/s (range 0.17–1.56?×?10^-3?mm²/s), respectively. There was a strong positive correlation between ADCs and Ds. For clinically relevant b value combinations, maximum deviation between ADCs including and excluding low b values (<100 s/mm²) was 11.8 %.

Conclusion

Selection of b values strongly affects ADCs of malignant breast lesions. However, by excluding low b values, ADCs approach biexponential Ds, demonstrating that microperfusion influences the diffusion signal. Thus, care should be taken when ADC calculation includes low b values.

Key Points

? Diffusion-weighted sequences are increasingly used in breast magnetic resonance imaging ? Diffusion-weighting (b) values strongly influence apparent diffusion coefficients of malignant lesions ? Exclusion of low b values reduces the apparent diffusion coefficient ? Flow-insensitive monoexponential apparent diffusion coefficients approach biexponential diffusion coefficients     

MRI-only lesions: application of diffusion-weighted imaging obviates unnecessary MR-guided breast biopsies

Objective

To assess if the application of diffusion-weighted imaging (DWI) obviates unnecessary MR-guided biopsies in suspicious breast lesions visible only on contrast-enhanced MRI (CE-MRI).

Methods

This institutional review board (IRB)-approved, retrospective, single-centre study included 101 patients (mean age, 49.5; SD 13.9 years) who underwent additional DWI at 1.5 T prior to MRI-guided biopsy of 104 lesions classified as suspicious for malignancy and visible on CE-MRI only. An experienced radiologist, blinded to histopathologic and follow-up results, measured apparent diffusion coefficient (ADC) values obtained from DWI. Diagnostic accuracy was investigated using receiver operating characteristics (ROC) analysis.

Results

Histopathology revealed 20 malignant and 84 benign lesions. Lesions were masses in 61 (15 malignant, 24.6 %) and non-masses in 43 cases (five malignant, 11.6 %). Mean ADC values were 1.53?±?0.38?×?10^?3 mm²/s in benign lesions and 1.06?±?0.27?×?10^?3 mm²/s in malignant lesions. ROC analysis revealed exclusively benign lesions if ADC values were greater than 1.58?×?10^?3 mm²/s. As a consequence, 29 false-positive biopsies (34.5 %) could have been avoided without any false-negative findings. Both in mass and in non-mass lesions, rule-in and rule-out criteria were identified using flexible ADC thresholds based on ROC analysis.

Conclusion

Additional application of DWI in breast lesions visible only on MRI can avoid false-positive, MR-guided biopsies. Thus, DWI should be an integral part of breast MRI protocols.

Key Points

? DWI measurements are a fast and helpful technique for improved breast lesion diagnosis ? DWI application in breast lesions visible only on MRI obviates false-positive, MR-guided biopsies ? Flexible ADC thresholds provide rule-in and rule-out criteria for breast lesion malignancy     

Diffusion-weighted MR imaging in liver metastases of colorectal cancer: reproducibility and biological validation

Objectives

Before diffusion-weighted imaging (DWI) can be implemented in standard clinical practice for response monitoring, data on reproducibility are needed to assess which differences outside the range of normal variation can be detected in an individual patient. In this study we assessed the reproducibility of the apparent diffusion coefficient (ADC) values in colorectal liver metastases. To provide a biological basis for these values, their relation with histopathology was assessed.

Methods

DWI was performed twice in 1 week in patients scheduled for metastasectomy of colorectal liver metastases. Correlation between ADC values and apoptosis marker p53, anti-apoptotic protein BCL-2, proliferation marker Ki67 and serum vascular endothelial growth factor (VEGF) concentration were assessed.

Results

A good reproducibility coefficient of the mean ADC (coefficient of reproducibility 0.20 × 10^?3?mm²/s) was observed in colorectal liver metastases (n?=?21). The ADC value was related to the proliferation index and BCL-2 expression of the metastases. Furthermore, in metastases recently treated with systemic therapy, the ADC was significantly higher (1.27 × 10^?3?mm²/s vs 1.05 × 10^?3?mm²/s, P?=?0.02).

Conclusions

The good reproducibility, correlation with histopathology and implied sensitivity for systemic treatment-induced anti-tumour effects suggest that DWI might be an excellent tool to monitor response in metastatic colorectal cancer.

Key Points

? ADC values are becoming important oncological biomarkers ? DWI provides reproducibile ADC values in colorectal liver metastases ? The coefficient of reproducibility of the mean ADC is 0.20 × 10 ^?3 ? mm ² /s ? ADC values correlate with proliferation index and are related to BCL-2 expression     

Characterization and therapy monitoring of head and neck carcinomas using diffusion-imaging-based intravoxel incoherent motion parameters—preliminary results

Introduction

Using the intravoxel incoherent motion (IVIM) model, diffusion-related coefficient (D) and perfusion-related parameter (f) can be measured. Here, we used IVIM imaging to characterize squamous cell carcinomas of head and neck (HNSCC) and evaluated its application in follow-up after nonsurgical organ preserving therapy.

Methods

Twenty-two patients with locally advanced HNSCC (clinical stage III to IVb) were examined before treatment using eight different b values (b?=?0, 50, 100, 150, 200, 250, 700, 800 s/mm²). All patients were followed for at least 7.5 months after conclusion of therapy. In 16 of these patients, follow-up MRI was available. Using the IVIM approach, f and D were extracted using a bi-exponential fit. For comparison, ADC maps were calculated.

Results

The initial values of f before therapy were located between 5.9 % and 12.9 % (mean: 9.4?±?2.4 %) except for two outliers (f?=?17.9 % and 18.2 %). These two patients exclusively displayed poor initial treatment response. Overall, high initial f (13.1?±?4.1 % vs. 9.1?±?2.4 %) and ADC (1.17?±?0.08?×?10^?3?mm²/s vs. 0.98?±?0.19?×?10^?3?mm²/s) were associated with poor short term outcome (n?=?6) after 7.5 months follow-up. D values before treatment were 0.98?×?10^?3?±?0.18 mm²/s and ADC values were 1.03?×?10^?3?±?0.18 mm²/s. At follow-up, in all primary responders, D (69?±?52 %), f (65?±?46 %), and ADC (68?±?49%) increased.

Conclusions

Our preliminary evaluation indicates that an initial high f may predict poor prognosis in HNSCC. In responders, a significant increase of all IVIM parameters after therapy was demonstrated.     

Application of the diffusion kurtosis model for the study of breast lesions

Objectives

To evaluate diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in the differentiation and characterisation of breast lesions.

Methods

Thirty-six women underwent breast magnetic resonance imaging (MRI) including a DWI sequence with multiple b-values (50–3,000 s/mm²). Mean values for apparent diffusion coefficient (ADC), mean diffusivity (MD) and mean kurtosis (MK) were calculated by lesion type and histological subtype. Differences and correlation between parameters were determined.

Results

Forty-four lesions were found. There were significant differences between benign and malignant lesions for all parameters (ADC, p?=?0.017; MD, p?=?0.028; MK, p?=?0.017). ADC and MD were higher for benign (1.96?±?0.41?×?10^?3 and 2.17?±?0.42?×?10^?3 mm²/s, respectively) than for malignant lesions (1.33?±?0.18?×?10^?3 and 1.52?±?0.50?×?10^?3 mm²/s). MK was higher for malignant (0.61?±?0.27) than benign lesions (0.37?±?0.18). We found differences between invasive ductal carcinoma (IDC) and fibroadenoma (FA) for all parameters (ADC, MD and MK): p?=?0.016, 0.022 and 0.016, respectively. FA and fibrocystic change (FC) showed differences only in MK (p?=?0.016).

Conclusions

Diffusion in breast lesions follows a non-Gaussian distribution. MK enables differentiation and characterisation of breast lesions, providing new insights into microstructural complexity. To confirm these results, further investigation in a broader sample should be performed.

Key Points

? The diffusion kurtosis model provides new information regarding breast lesions ? MD and MK are valid parameters to characterise tissue microstructure ? MK enables improved lesion differentiation ? MK is able to differentiate lesions that display similar ADC values     

Diffusion-weighted MR imaging for differentiating borderline from malignant epithelial tumours of the ovary: pathological correlation

Objectives

To investigate diffusion-weighted (DW) magnetic resonance (MR) imaging for differentiating borderline from malignant epithelial tumours of the ovary.

Methods

This retrospective study included 60 borderline epithelial ovarian tumours (BEOTs) in 48 patients and 65 malignant epithelial ovarian tumours (MEOTs) in 54 patients. DW imaging as well as conventional MR imaging was performed. Signal intensity on DW imaging was assessed and apparent diffusion coefficient (ADC) value was measured. The results were correlated with histopathology and cell density.

Results

The majority of MEOTs showed high signal intensity on DW imaging, whereas most BEOTs showed low or moderate signal intensity (P?=?0.000). The mean ADC value of the solid components in BEOTs (1.562?±?0.346?×?10^?3 mm²/s) was significantly higher than in MEOTs (0.841?±?0.209?×?10^?3 mm²/s). A threshold value of 1.039?×?10^?3 mm²/s permitted the distinction with a sensitivity of 97.0 %, a specificity of 92.2 % and an accuracy of 96.4 %. There was an inverse correlation between ADC value and cell density (r?=??0.609; P?=?0.0000) which was significantly lower in BEOTs than in MEOTs.

Conclusions

DW imaging is useful for differentiating borderline from malignant epithelial tumours of the ovary.

Key Points

? DW MR imaging is useful for differentiating BEOTs from MEOTs. ? Patients with BEOTs are treated differently from patients with MEOTs. ? Conservative fertility-sparing laparoscopic surgery can be performed in patients with BEOTs. ? BEOTs often affect young women of childbearing age.     

Diffusion-weighted MRI for distinguishing non-neoplastic cysts from solid masses in the mediastinum: problem-solving in mediastinal masses of indeterminate internal characteristics on CT

Objectives

To evaluate the usefulness of diffusion-weighted (DW) magnetic resonance images for distinguishing non-neoplastic cysts from solid masses of indeterminate internal characteristics on computed tomography (CT) in the mediastinum.

Methods

We enrolled 25 patients with pathologically proved mediastinal masses who underwent both thoracic CT and magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI). MRI was performed in patients with mediastinal masses of indeterminate internal characteristics on CT. Two thoracic radiologists evaluated the morphological features and quantitatively measured the net enhancement of the masses at CT. They also reviewed MR images including unenhanced T1- and T2-weighted images, gadolinium-enhanced images and DW images.

Results

The enrolled patients had 15 solid masses and ten non-neoplastic cysts. Although the morphological features and the extent of enhancement on CT did not differ significantly between solid and cystic masses in the mediastinum (P?>?0.05), non-neoplastic cysts were distinguishable from solid masses by showing signal suppression on high-b-value DW images or high apparent diffusion coefficient (ADC) values of more than 2.5?×?10^-3 mm²/s (P?<?0.001). ADC values of non-neoplastic cysts (3.67?±?0.87?×?10^-3 mm²/s) were significantly higher than that of solid masses (1.46?±?0.50?×?10^-3 mm²/s) (P?<?0.001).

Conclusions

DWI can help differentiate solid and cystic masses in the mediastinum, even when CT findings are questionable.

Key Points

? Non-invasive diagnosis of non-neoplastic cysts can save surgical biopsy or excision. ? Conventional CT or MRI findings cannot always provide a confident diagnosis. ? Mediastinal masses can be well-characterised with DWI. ? Non-neoplastic mediastinal cysts show significantly higher ADC values than cystic tumours. ? DWI is useful to determine treatment strategy.     

Diffusion-weighted imaging in breast lesion evaluation

Purpose

The purpose of this study was to investigate the ability of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the detection and characterisation of breast lesions.

Materials and methods

From September 2005 to September 2007, 86 patients with breast lesions who underwent magnetic resonance imaging (MRI) in our department were included in our study. MRI was performed with a 1.5-T unit using a standard protocol including DWI sequence. For each breast lesion, the ADC value was calculated and compared with that of normal breast tissue and to the definitive pathological diagnosis. Mann-Whitney U and Kruskal-Wallis tests were used for statistical analysis.

Results

A total of 126 breast lesions were detected. Pathology results revealed 100 malignant and 26 benign lesions. Mean diameter of lesions was 26.02 mm (range 4–90 mm), including 52 lesions ≤15 mm in size. Mean ADC value of normal glandular tissue was 1.55×10^?3 mm²/s. Mean ADC value of malignant lesions was 0.97×10^?3 mm²/s. Mean ADC value for benign lesions was 1.66×10^?3 mm²/s. Benign lesions showed ADC values significantly higher than malignant lesions (p<0.0001).

Conclusions

DWI provides reliable information to support MRI diagnosis of breast masses. ADC value appears a promising adjunctive parameter in distinguishing malignant from benign breast lesions.     

Diffusion-weighted magnetic resonance imaging of thymoma: ability of the Apparent Diffusion Coefficient in predicting the World Health Organization (WHO) classification and the Masaoka-Koga staging system and its prognostic significance on disease-free survival

Objectives

To evaluate the usefulness of diffusion-weighted magnetic resonance for distinguishing thymomas according to WHO and Masaoka-Koga classifications and in predicting disease-free survival (DFS) by using the apparent diffusion coefficient (ADC).

Methods

Forty-one patients were grouped based on WHO (low-risk vs. high-risk) and Masaoka-Koga (early vs. advanced) classifications. For prognosis, seven patients with recurrence at follow-up were grouped separately from healthy subjects. Differences on ADC levels between groups were tested using Student-t testing. Logistic regression models and areas under the ROC curve (AUROC) were estimated.

Results

Mean ADC values were different between groups of WHO (low-risk?=?1.58?±?0.20?×?10^-3mm²/sec; high-risk?=?1.21?±?0.23?×?10^-3mm²/sec; p?<?0.0001) and Masaoka-Koga (early?=?1.43?±?0.26?×?10^-3mm²/sec; advanced?=?1.31?±?0.31?×?10^-3mm²/sec; p?=?0.016) classifications. Mean ADC of type-B3 (1.05?±?0.17?×?10^-3mm²/sec) was lower than type-B2 (1.32?±?0.20?×?10^-3mm²/sec; p?=?0.023). AUROC in discriminating groups was 0.864 for WHO classification (cut-point?=?1.309?×?10^-3mm²/sec; accuracy?=?78.1 %) and 0.730 for Masaoka-Koga classification (cut-point?=?1.243?×?10^-3mm²/sec; accuracy?=?73.2 %). Logistic regression models and two-way ANOVA were significant for WHO classification (odds ratio[OR]?=?0.93, p?=?0.007; p?<?0.001), but not for Masaoka-Koga classification (OR?=?0.98, p?=?0.31; p?=?0.38). ADC levels were significantly associated with DFS recurrence rate being higher for patients with ADC?≤?1.299?×?10^-3mm²/sec (p?=?0.001; AUROC, 0.834; accuracy?=?78.0 %).

Conclusions

ADC helps to differentiate high-risk from low-risk thymomas and discriminates the more aggressive type-B3. Primary tumour ADC is a prognostic indicator of recurrence.

Key Points

? DW-MRI is useful in characterizing thymomas and in predicting disease-free survival. ? ADC can differentiate low-risk from high-risk thymomas based on different histological composition ? The cutoff-ADC-value of 1.309?×?10 ^-3 mm ² /sec is proposed as optimal cut-point for this differentiation ? The ADC ability in predicting Masaoka-Koga stage is uncertain and needs further validations ? ADC has prognostic value on disease-free survival and helps in stratification of risk

     

Diffusion weighted imaging in differentiating malignant and benign neuroblastic tumors

Purpose

Our aim was to assess diffusion weighted imaging (DWI) of neuroblastic tumors and whether apparent diffusion coefficient (ADC) value may have a role in discrimination among neuroblastoma, ganglioneuroblastoma and ganglioneuroma.

Material and methods

The DWIs (b = 0–800 s/mm²) of 24 children (13 girls, 11 boys) who were diagnosed neuroblastic tumors on histopathological examination (neuroblastoma = 15, ganglioneuroblastoma = 5, ganglioneuroma = 4) were evaluated retrospectively. The ADC maps were performed by drawing freehand ROI on PACS (Sectra Workstation IDS7, Linköping, Sweden).

Results

We observed a significant decrease in ADC value of neuroblastomas 0.869 ± 0.179 × 10^?3 mm²/s compared to ganglioneuroblastomas 0.97 ± 0.203 × 10^?3 mm²/s and ganglioneuromas 1.147 ± 0.299 × 10^?3 mm²/s (p = 0.026). There was no significant difference in between ganglioneuroblastoma and ganglioneuroma (p = 0.16). In detecting neuroblastomas; the sensitivity, specificity, negative and positive predictive values of ADC were 74, 67, 78.6, 66 % respectively with a cut-off value of 0.93 × 10^?3 mm²/s.

Conclusion

Our study stands out as the most comprehensive study with larger sample size on this topic. Moreover, we are able to suggest a cut-off value which can discriminate neuroblastoma from ganglioneuroblastoma and ganglioneuroma. We believe that ADC will evolve to an objective, quantitative measurement in discrimination among malignant and benign neuroblastic tumors.

     

Preoperative lymph node staging in patients with primary prostate cancer: comparison and correlation of quantitative imaging parameters in diffusion-weighted imaging and 11C-choline PET/CT

Purpose

To compare the diagnostic performance of DWI and 11C-choline PET/CT in the assessment of preoperative lymph node status in patients with primary prostate cancer.

Material and methods

Thirty-three patients underwent DWI and 11C-choline PET/CT prior to prostatectomy and extended pelvic lymph node dissection. Mean standardised uptake value (SUV_mean) and mean apparent diffusion coefficient (ADC) of 76 identified lymph nodes (LN) were measured and correlated with histopathology. ADC values and SUVs were compared using linear regression analysis.

Results

A significant difference between benign and malignant LN was observed for ADC values (1.17 vs. 0.96?×?10^-3 mm²/s; P?<?0.001) and SUV_mean (1.61 vs. 3.20; P?<?0.001). ROC analysis revealed an optimal ADC threshold of 1.01?×?10^-3 mm²/s for differentiating benign from malignant LN with corresponding sensitivity/specificity of 69.70 %/78.57 % and an area under the curve (AUC) of 0.785. The optimal threshold for SUV_mean was 2.5 with corresponding sensitivity/specificity of 69.72 %/90.48 % and with an AUC of 0.832. ADC values and SUV_mean showed a moderate significant inverse correlation (r?=?-0.63).

Conclusion

Both modalities reveal similar moderate diagnostic performance for preoperative lymph node staging of prostate cancer, not justifying their application in routine clinical practice at this time. The only moderate inverse correlation between ADC values and SUV_mean suggests that both imaging parameters might provide complementary information on tumour biology.

Key Points

? Conventional imaging shows low performance for lymph node staging in prostate cancer. ? DWI and 11C-choline PET/CT both provide additional functional information ? Both functional modalities reveal only moderate diagnostic performance.     

Apparent diffusion coefficient modifications in assessing gastro-oesophageal cancer response to neoadjuvant treatment: comparison with tumour regression grade at histology

Objectives

To assess changes in apparent diffusion coefficient (ΔADC) and volume (ΔV) after neoadjuvant treatment (NT), and tumour regression grade (TRG) in gastro-oesophageal cancers (GEC), and to discriminate responders from non-responders.

Methods

Thirty-two patients with biopsy-proven locally-advanced GEC underwent diffusion weighted magnetic resonance imaging (DWI) pre- and post-NT. Lesion ADC, volume, ΔADC and ΔV were calculated. TRG 1-2-3 patients were classified as R; TRG 4-5 as non-responders. ΔADC-TRG and ΔV-TRG correlations, pre-NT and post-NT ADC, ΔADC and ΔV cut-off values for responders and non-responders were calculated. Two readers measured mean tumour ADCs and interobserver variability was calculated. (Spearman’s and intraclass correlation coefficient [ICC]).

Results

The interobserver reproducibility was very good both for pre-NT (Spearman’s rho?=?0.8160; ICC?=?0.8993) and post-NT (Spearman’s rho?=?0.8357; ICC?=?0.8663). Responders showed lower pre-NT ADC (1.32 versus 1.63?×?10^?3?mm²/s; P?=?0.002) and higher post-NT ADC (2.22 versus 1.51?×?10^?3?mm²/s; P?=?0.001) than non-responders and ADC increased in responders (ΔADC, 85.45 versus ?8.21 %; P?=?0.00005). ΔADC inversely correlated with TRG (r?=??0.71, P?=?0.000004); no difference in ΔV between responders and non-responders (?50.92 % versus ?14.12 %; P?=?0.068) and no correlation ΔV-TRG (r?=?0.02 P?=?0.883) were observed.

Conclusions

The ADC can be used to assess gastro-oesophageal tumour response to neoadjuvant treatment as a reliable expression of tumour regression.

Key Points

? DWI is now being used to assess many cancers. ? Change in ADC measurements offer new information about oesophageal tumours. ? ADC changes are more reliable than dimensional criteria in assessing neoadjuvant treatment. ? Such ADC assessment could optimise management of locally advanced gastro-oesophageal cancers.     

Apparent diffusion coefficient of the vertebral bone marrow in children with Gaucher's disease type I and III

Purpose

To assess apparent diffusion coefficient (ADC) as a quantitative parameter for detection of vertebral bone marrow infiltration in children with Gaucher’s disease type I and III.

Material and methods

Prospective study was conducted on 20 infants and children (14 M, 6 F; aged 31–61 months; mean age 46 months) with Gaucher’s disease type I (n?=?13) and III (n?=?7), and 20 age and sex matched controls. They underwent routine and diffusion-weighted MR imaging of the lumbar spine using echo planar imaging with b value of 0, 500 and 1000 sec/mm2. The ADC value of the lumbar vertebral bone marrow was compared in different phenotypes and genotypes; and correlated with bone marrow burden score (BMB), chitotriosidase level, hemoglobin and platelet count.

Results

The mean ADC value of marrow infiltration in patients with Gaucher’s disease (0.39?±?0.06?×?10^?3 mm²/s) was significantly lower (P?=?0.001) than that of vertebral bone marrow in controls (0.54?±?0.05?×?10^?3 mm²/s). The cut-off ADC value used to differentiate patients with Gaucher’s disease from controls was (0.47?×?10^?3 mm²/s); with sensitivity of 95 %; specificity of 95 % and area under the curve of 0.986. The L444P/L444P mutation had significantly lower ADC value compared to other mutations (P?=?0.001). The mean ADC value of the bone marrow negatively correlated with BMB (r?=??0.831; P?=?0.001), and biomarkers of disease activity including chitotriosidase (r?=??0.542; P?=?0.014), hemoglobin (r?=??0.727; P?=?0.001) and platelets (r?=??0.698; P?=?0.001).

Conclusion

We concluded that there is significant difference in the ADC value of vertebral bone marrow between children with Gaucher’s disease and controls, and the ADC value correlated well with genotyping and some biomarkers of disease activity.     

Usefulness of diffusion-weighted MR imaging in the evaluation of pulmonary lesions

Purpose

The role of diffusion-weighted MR imaging (DWI) in the differential diagnosis of pulmonary malignant tumours and solid benign lesions was investigated.

Methods

Sixty-two patients with 66 lesions underwent conventional MRI and DWI (diffusion factor of 0 and 500 s/mm²) examinations with 1.5-T MRI. The signal intensity of DWI images was observed and the apparent diffusion coefficient (ADC) values of the lesions were measured. Statistical analyses were performed with the independent samples t test, Pearson’s chi-square test and receiver operating characteristic (ROC) analysis.

Results

The signal intensities of pulmonary malignant tumours and solid benign lesions were not significantly different, but the ADC value of benign lesions was statistically higher than that of malignant tumours (p?=?0.001). By ROC analysis, the optimal threshold of ADC was 1.400?×?10^–3 mm²/s and the sensitivity and specificity were 83.3% and 74.1%, respectively. There were statistical differences between small cell carcinoma (SCLC) and non-small cell carcinoma (NSCLC) as well; the former was lower than the latter (p?=?0.007).

Conclusion

Our data indicate that quantitative analysis of ADC values may help diagnose or distinguish pulmonary lesions, and it also provides a promising method for characterising the pulmonary masses.     

Correlations between diffusion-weighted imaging and breast cancer biomarkers

Objective

We evaluated whether the apparent diffusion coefficient (ADC) provided by diffusion-weighted imaging (DWI) varies according to biological features in breast cancer.

Methods

DWI was performed in 190 patients undergoing dynamic contrast-enhanced magnetic resonance imaging (MRI) for local staging. For each of the 192 index cancers we studied the correlation between ADC and classical histopathological and immunohistochemical breast tumour features (size, histological type, grade, oestrogen receptor [ER] and Ki-67 expression, HER2 status). ADC was compared with immunohistochemical surrogates of the intrinsic subtypes (Luminal A; Luminal B; HER2-enriched; triple-negative). Correlations were analysed using the Mann–Whitney U and Kruskal–Wallis H tests.

Results

A weak, statistically significant correlation was observed between ADC values and the percentage of ER-positive cells (-0.168, P?=?0.020). Median ADC values were significantly higher in ER-negative than in ER-positive tumours (1.110 vs 1.050?×?10^-3?mm²/s, P?=?0.015). HER2-enriched tumours had the highest median ADC value (1.190?×?10^-3?mm²/s, range 0.950–2.090). Multiple comparisons showed that this value was significantly higher than that of Luminal A (1.025?×?10^-3?mm²/s [0.700–1.340], P?=?0.004) and Luminal B/HER2-negative (1.060?×?10^-3?mm²/s [0.470–2.420], P?=?0.008) tumours. A trend towards statistical significance (P?=?0.018) was seen with Luminal B/HER2-positive tumours.

Conclusions

ADC values vary significantly according to biological tumour features, suggesting that cancer heterogeneity influences imaging parameters.

Key Points

? DWI may identify biological heterogeneity of breast neoplasms. ? ADC values vary significantly according to biological features of breast cancer. ? Compared with other types, HER2-enriched tumours show highest median ADC value. ? Knowledge of biological heterogeneity of breast neoplasm may improve imaging interpretation.     

Diffusion weighted imaging of the normal breast: reproducibility of apparent diffusion coefficient measurements and variation with menstrual cycle and menopausal status

Objectives

To establish the reproducibility of apparent diffusion coefficient (ADC) measurements in normal fibroglandular breast tissue and to assess variation in ADC values with phase of the menstrual cycle and menopausal status.

Methods

Thirty-one volunteers (13 premenopausal, 18 postmenopausal) underwent magnetic resonance twice (interval 11–22?days) using diffusion-weighted MRI. ADC_total and a perfusion-insensitive ADC_high (omitting b?=?0) were calculated. Reproducibility and inter-observer variability of mean ADC values were assessed. The difference in mean ADC values between the two phases of the menstrual cycle and the postmenopausal breast were evaluated.

Results

ADC_total and ADC_high showed good reproducibility (r%?=?17.6, 22.4). ADC_high showed very good inter-observer agreement (kappa?=?0.83). The intraclass correlation coefficients (ICC) were 0.93 and 0.91. Mean ADC values were significantly lower in the postmenopausal breast (ADC_total 1.46?±?0.3?×?10^-3?mm²/s, ADC_high 1.33?±?0.3?×?10^-3?mm²/s) compared with the premenopausal breast (ADC_total 1.84?±?0.26?×?10^-3?mm²/s, ADC_high 1.77?±?0.26?×?10^-3?mm²/s; both P?total P?=?0.2, ADC_high P?=?0.24) or between postmenopausal women taking or not taking oestrogen supplements (ADC_total P?=?0.6, ADC_high P?=?0.46).

Conclusions

ADC values in fibroglandular breast tissue are reproducible. Lower ADC values within the postmenopausal breast may reduce diffusion-weighted contrast and have implications for accurately detecting tumours.

Key Points

? ADC values from fibroglandular breast tissue are measured reproducibly by multiple observers. ? Mean ADC values were significantly lower in postmenopausal than premenopausal breast tissue. ? Mean ADC values did not vary significantly with menstrual cycle. ? Low postmenopausal ADC values may hinder tumour detection on DW-MRI.