Recurrent glioblastoma multiforme versus radiation injury: a multiparametric 3-T MR approach

Objective

The discrimination between recurrent glioma and radiation injury is often a challenge on conventional magnetic resonance imaging (MRI). We verified whether adding and combining proton MR spectroscopic imaging (¹H-MRSI), diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) information at 3 Tesla facilitate such discrimination.

Materials and methods

Twenty-nine patients with histologically verified high-grade gliomas, who had undergone surgical resection and radiotherapy, and had developed new contrast-enhancing lesions close to the treated tumour, underwent MRI, ¹H-MRSI, DWI and PWI at regular time intervals. The metabolite ratios choline (Cho)/normal( _n )Cho _n , N-acetylaspartate (NAA)/NAA _n , creatine (Cr)/Cr _n , lactate/lipids (LL)/LL _n , Cho/Cr _n , NAA/Cr _n , Cho/NAA, NAA/Cr and Cho/Cr were derived from ¹H-MRSI; the apparent diffusion coefficient (ADC) from DWI; and the relative cerebral blood volume (rCBV) from PWI.

Results

In serial MRI, recurrent gliomas showed a progressive enlargement, and radiation injuries showed regression or no modification. Discriminant analysis showed that discrimination accuracy was 79.3 % when considering only the metabolite ratios (predictor, Cho/Cr _n ), 86.2 % when considering ratios and ADC (predictors, Cho/Cr _n and ADC), 89.7 % when considering ratios and rCBV (predictors, Cho/Cr _n , Cho/Cr and rCBV), and 96.6 % when considering ratios, ADC and rCBV (predictors, Cho/Cho _n , ADC and rCBV).

Conclusions

The multiparametric 3-T MR assessment based on ¹H-MRSI, DWI and PWI in addition to MRI is a useful tool to discriminate tumour recurrence/progression from radiation effects.     

Immediate post-operative MRI suggestive of the site and timing of glioblastoma recurrence after gross total resection: a retrospective longitudinal preliminary study

Objectives

To retrospectively identify morphological and physiological post-operative magnetic resonance imaging (MRI) characteristics predictive of glioblastoma recurrences after gross total resection (gross-TR).

Methods

Resection margins of 24 glioblastoma were analysed immediately post-operatively (MRI?≤?2 h) and early post-operatively (24 h?≤?MRI?≤?48 h), and subdivided into areas with and without subtle contrast enhancement previously considered non-specific. On follow-up MRI, tumour regrowth areas were subdivided according to recurrence extent (focally/extended) and delay (≤6 and ≥12 months). Co-registration of pre-operative, immediately post-operative and early post-operative MRI with the first follow-up MRI demonstrating recurrence authorised their morphological (contrast enhancements) and physiological (rCBV) characterisation.

Results

Morphologically, on immediately post-operative MRI, micro-nodular and frayed enhancements correlate significantly with early recurrences (≤6 months). After gross-TR the absence of these enhancements is associated with a significant increase in progression-free survival (61 vs 15 weeks respectively) and overall survival (125 vs 51 weeks respectively). Physiologically, areas with a future focal recurrence have a trend toward higher rCBV than other areas.

Conclusion

Immediately post-operative topography of micro-nodular and frayed enhancements is suggestive of recurrence location and delay. Absence of such enhancements is associated with a fourfold increase in progression-free survival and a 2.5-fold increase in overall survival.

Key Points

? Immediately post-operative MRI reveals contrast enhancement after glioblastoma gross total resection. ? Immediately post-operative micro-nodular and frayed enhancement correlate with early recurrence. ? Absence of micro-nodular/frayed enhancement is associated with 61 weeks’ progression-free survival. ? Absence of micro-nodular/frayed enhancement is associated with 125 weeks’ overall survival.     

Morphological, functional and metabolic imaging biomarkers: assessment of vascular-disrupting effect on rodent liver tumours

Objectives

To evaluate effects of a vascular-disrupting agent on rodent tumour models.

Methods

Twenty rats with liver rhabdomyosarcomas received ZD6126 intravenously at 20 mg/kg, and 10 vehicle-treated rats were used as controls. Multiple sequences, including diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) with the microvascular permeability constant (K), were acquired at baseline, 1 h, 24 h and 48 h post-treatment by using 1.5-T MRI. [¹⁸F]fluorodeoxyglucose micro-positron emission tomography (¹⁸F-FDG µPET) was acquired pre- and post-treatment. The imaging biomarkers including tumour volume, enhancement ratio, necrosis ratio, apparent diffusion coefficient (ADC) and K from MRI, and maximal standardised uptake value (SUV_max) from FDG µPET were quantified and correlated with postmortem microangiography and histopathology.

Results

In the ZD6126-treated group, tumours grew slower with higher necrosis ratio at 48 h (P?<?0.05), corresponding well to histopathology; tumour K decreased from 1 h until 24 h, and partially recovered at 48 h (P?<?0.05), parallel to the evolving enhancement ratios (P?<?0.05); ADCs varied with tumour viability and perfusion; and SUV_max dropped at 24 h (P?<?0.01). Relative K of tumour versus liver at 48 h correlated with relative vascular density on microangiography (r?=?0.93, P?<?0.05).

Conclusions

The imaging biomarkers allowed morphological, functional and metabolic quantifications of vascular shutdown, necrosis formation and tumour relapse shortly after treatment. A single dose of ZD6126 significantly diminished tumour blood supply and growth until 48 h post-treatment.     

Simulated required accuracy of image registration tools for targeting high-grade cancer components with prostate biopsies

Objectives

To estimate the required spatial alignment accuracy for correctly grading 95 % of peripheral zone (PZ) prostate cancers using a system for multiparametric magnetic resonance (MR)-guided ultrasound (US) biopsies.

Methods

PZ prostate tumours were retrospectively annotated on multiparametric MR series using prostatectomy specimens as reference standard. Tumours were grouped based on homogeneous and heterogeneous apparent diffusion coefficient (ADC) values using an automated ADC texture analysis method. The proportion of heterogeneous tumours containing a distinct, high Gleason grade tumour focus yielding low ADC values was determined. Both overall tumour and high-grade focal volumes were calculated. All high-grade target volumes were then used in a simulated US biopsy system with adjustable accuracy to determine the hit rate.

Results

An ADC-determined high-grade tumour focus was found in 63 % of the PZ prostate tumours. The focal volumes were significantly smaller than the total tumour volumes (median volume of 0.3 ml and 1.1 ml respectively). To correctly grade 95 % of the aggressive tumour components the target registration error (TRE) should be smaller than 1.9 mm.

Conclusions

To enable finding the high Gleason grade component in 95 % of PZ prostate tumours with MR-guided US biopsies, a technical registration accuracy of 1.9 mm is required.

Key Points

? MRI can identify foci of prostatic cancer with reduced apparent diffusion coefficients ? Sixty-three per cent of prostatic peripheral zone tumours contain high-grade tumour low ADC foci ? The median volume of such foci is 0.3 ml ? Biopsy targets are significantly smaller than whole tumour volumes ? Simulated registration accuracy is 1.9 mm for correctly grading 95 % of tumours     

Dynamic susceptibility contrast (DSC) perfusion MRI in differential diagnosis between radionecrosis and neoangiogenesis in cerebral metastases using rCBV,rCBF and K2

Introduction

Distinction between treatment-related changes and tumour recurrence in patients who have received radiation treatment for brain metastases can be difficult on conventional MRI. In this study, we investigated the ability of dynamic susceptibility contrast (DSC) perfusion in differentiating necrotic changes from pathological angiogenesis and compared measurements of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF) and K2, using a dedicated software.

Methods

Twenty-nine patients with secondary brain tumors were included in this retrospective study and underwent DSC perfusion MRI with a 3-month follow-up imaging after chemo- or radiation-therapy. Region-of-interests were drawn around the contrast enhancing lesions and measurements of rCBV, rCBF and K2 were performed in all patients. Based on subsequent histological examination or clinico-radiological follow-up, the cohort was divided in two groups: recurrent disease and stable disease. Differences between the two groups were analyzed using the Student’s t test. Sensitivity, specificity and diagnostic accuracy of rCBV measurements were analyzed considering three different cut-off values.

Results

Between patients with and without disease, only rCBV and rCBF values were significant (p < 0.05). The only cut-off value giving the best diagnostic accuracy of 100% was rCBV = 2.1 (sensitivity = 100%; specificity = 100%). Patients with tumor recurrence showed a higher mean value of rCBV (mean = 4.28, standard deviation = 2.09) than patients with necrotic-related changes (mean = 0.77, standard deviation = 0.44).

Conclusion

DSC-MRI appears a clinically useful method to differentiate between tumor recurrence, tumor necrosis and pseudoprogression in patients treated for cerebral metastases. Relative CBV using a cut-off value of 2.1 proved to be the most accurate and reliable parameter.

     

Locally advanced rectal cancer: diffusion-weighted MR tumour volumetry and the apparent diffusion coefficient for evaluating complete remission after preoperative chemoradiation therapy

Objective

To evaluate DW MR tumour volumetry and post-CRT ADC in rectal cancer as predicting factors of CR using high b values to eliminate perfusion effects.

Methods

One hundred rectal cancer patients who underwent 1.5-T rectal MR and DW imaging using three b factors (0, 150, and 1,000 s/mm²) were enrolled. The tumour volumes of T2-weighted MR and DW images and pre- and post-CRT ADC_150–1000 were measured. The diagnostic accuracy of post-CRT ADC, T2-weighted MR, and DW tumour volumetry was compared using ROC analysis.

Results

DW MR tumour volumetry was superior to T2-weighted MR volumetry comparing the CR and non-CR groups (P?<?0.001). Post-CRT ADC showed a significant difference between the CR and non-CR groups (P?=?0.001). The accuracy of DW tumour volumetry (A_z?=?0.910) was superior to that of T2-weighed MR tumour volumetry (A_z?=?0.792) and post-CRT ADC (A_z?=?0.705) in determining CR (P?=?0.015). Using a cutoff value for the tumour volume reduction rate of more than 86.8 % on DW MR images, the sensitivity and specificity for predicting CR were 91.4 % and 80 %, respectively.

Conclusion

DW MR tumour volumetry after CRT showed significant superiority in predicting CR compared with T2-weighted MR images and post-CRT ADC.

Key Points

? Diffusion-weighted MR (DWMR) imaging offers new information about rectal cancer. ? DWMR helps to predict complete remission after chemoradiotherapy in patients with advanced rectal cancer. ? DWMR provides more accurate diagnostic information than T2-weighted MRI. ? Apparent diffusion coefficients can predict CR, but they have certain clinical limitations.     

Value of diffusion-weighted imaging in predicting parametrial invasion in stage IA2–IIA cervical cancer

Objective

To investigate the value of diffusion-weighted imaging (DWI) in evaluating parametrial invasion (PMI) in stage IA2–IIA cervical cancer.

Methods

A total of 117 patients with stage IA2–IIA cervical cancer who underwent preoperative MRI and radical hysterectomy were included in this study. Preoperative clinical variables and MRI variables were analysed and compared between the groups with and without pathologically proven PMI.

Results

All variables except age were significantly different between patients with and without pathologic PMI (P?<?0.05). All variables except squamous cell carcinoma (SCC) antigen were also significantly correlated with pathologic PMI on univariate analysis (P?<?0.05). Multivariate analysis indicated that PMI on MRI (P?<?0.001) and tumour apparent diffusion coefficient (ADC) (P?=?0.029) were independent predictors of pathologic PMI. Area under the curve of PMI on MRI increased significantly from 0.793 to 0.872 when combined with tumour ADC (P?=?0.002). When PMI on MRI was further stratified by tumour ADC, the false negative rate was 2.0 % (1/49).

Conclusion

In stage IA2–IIA cervical cancer, tumour ADC and PMI on MRI seem to be independent predictors of pathologic PMI. Combining the two predictors improved the diagnostic performance of identifying patients at low risk of pathologic PMI.

Key points

? Accurate PMI prediction is essential for appropriate treatment planning ? Tumour ADC appears to be an independent predictor of pathologic PMI ? Adding DWI to MRI improves accuracy for identifying low-risk patients for PMI     

Hepatocellular carcinoma (HCC) in non-cirrhotic liver: clinical,radiological and pathological findings

Objectives

Our aim was to evaluate the clinical and pathological findings, mutidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI) appearances, treatment and 1-year survival of patients with HCC in non-cirrhotic liver.

Methods

Histopathological and laboratory findings of 30 non-cirrhotic patients with 32 HCCs were reviewed retrospectively. MDCT and gadobenate dimeglumine-enhanced MR images were evaluated in consensus by two radiologists in terms of HCC size, presence of tumour capsule, necrosis, haemorrhage, fat and calcification, and vascular involvement. Imaging patterns were compared directly with HCC findings in a matched group of cirrhotic patients.

Results

No differences between non-cirrhotic and cirrhotic patients were noted in terms of serum α-fetoprotein levels (elevated in 11 [36.7 %] and 21 [35 %] patients, respectively). The imaging appearance at CT and contrast-enhanced MRI was typical in 27 (84.3 %) and 28 (87.5 %) cases respectively. Most lesions presented as a well-differentiated large solitary mass, with well-defined margins, areas of necrosis and peripheral capsule. No significant differences in HCC pattern were observed between cirrhotic and non-cirrhotic liver.

Conclusions

In non-cirrhotic patients, HCC is more likely to manifest as an asymptomatic mass with elevation of serum tumour markers similar to that seen in cirrhotic patients. HCC in cirrhotic and non-cirrhotic livers show similar enhancement patterns.

Key Points

• HCC shows similar CT/MRI pattern in cirrhotic and non-cirrhotic livers.
• Non-invasive diagnostic criteria for HCC should also be extended to non-cirrhotic livers.
• No differences were found between α-fetoprotein levels in non-cirrhotic and cirrhotic patients.

     

Simple measurements on diffusion-weighted MR imaging for assessment of complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Purpose

To determine diagnostic performance of simple measurements on diffusion-weighted MR imaging (DWI) for assessment of complete tumour response (CR) after neoadjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer (LARC) by signal intensity (SI) and apparent diffusion coefficient (ADC) measurements.

Materials and methods

Sixty-five patients with LARC who underwent neoadjuvant CRT and subsequent surgery were included. Patients underwent pre-CRT and post-CRT 3.0 T MRI. Regions of interest of the highest brightness SI were included in the tumour volume on post-CRT DWI to calculate the SI_lesion, rSI, ADC_lesion and rADC; diagnostic performance was compared by using the receiver operating characteristic (ROC) curves. In order to validate the accuracy and reproducibility of the current strategy, the same procedure was reproduced in 80 patients with LARC at 1.5 T MRI.

Results

Areas under the ROC curve for identification of a CR, based on SI_lesion, rSI, ADC_lesion, and rADC, respectively, were 0.86, 0.94, 0.66, and 0.71 at 3.0 T MRI, and 0.92, 0.91, 0.64, and 0.61 at 1.5 T MRI.

Conclusion

Post-CRT DWI SI_lesion and rSI provided high diagnostic performance in assessing CR and were significantly more accurate than ADC_lesion, and rADC at 3.0 T MRI and 1.5 T MRI.

Key Points

? Signal intensity (SI _lesion ) and rSI are accurate for assessment of complete response. ? rSI seems to be superior to SI _lesion at 3.0 T MRI. ? ADC or rADC measurements are not accurate for assessment of complete response.     

The value of apparent diffusion coefficient in the assessment of cervical cancer

Objectives

To evaluate the potential value of apparent diffusion coefficient (ADC) measurement in the assessment of cervical cancer.

Methods

One hundred twelve patients with cervical cancer and 67 control subjects underwent diffusion-weighted imaging (DWI) in addition to routine MR imaging at 3.0-T MRI before therapy. All ADCs were calculated from b?=?0, 600 s/mm² and b?=?0, 1,000 s/mm².

Results

The ADCs of cervical cancer were significantly lower than those of normal cervix for both ADC maps. There was a statistically significant difference between the ADCs of well-/moderately differentiated (G1/2) tumours and poorly differentiated (G3) tumours, between the ADCs of squamous cell carcinoma and adenocarcinoma, between the pretherapy ADCs of tumour recurrence or metastasis and tumour free patients after radical hysterectomy for both ADC maps. There was no significant difference among the ADCs of cervical cancer when divided by other features (FIGO, lymph node status, tumour size and age groups) for both ADC maps.

Conclusion

ADC values were reliable for differentiating cervical cancer from normal cervix with high diagnostic accuracy. The ADCs can be used to indicate the degree and histological type of cervical cancer, although there is some overlap. G3 tumours and lower ADCs may indicate poor prognosis. The diagnostic accuracy was equal for both ADC maps.

Key Points

? Diffusion-weighted magnetic resonance imaging provides new information about cervical cancer ? Apparent diffusion coefficient values can differentiate cervical cancer from normal cervical tissue ? Pretherapy ADCs can also predict the prognosis for patients who have undergone radical hysterectomy ? ADCs can help indicate the degree and histological type of cervical cancer ? Patients with G3 tumours and lower ADCs may benefit from preoperative chemoradiation     

The combination of FDG PET and dynamic contrast-enhanced MRI improves the prediction of disease-free survival in patients with advanced breast cancer after the first cycle of neoadjuvant chemotherapy

Purpose

The aim of this study was to investigate the potential of FDG PET/CT and MRI in predicting disease-free survival (DFS) after neoadjuvant chemotherapy (NAC) and surgery in patients with advanced breast cancer.

Methods

The analysis included 54 women with advanced breast cancer. All patients received three cycles of NAC, underwent curative surgery, and then received three cycles of additional chemotherapy. Before and after the first cycle of NAC, all patients underwent sequential PET/CT and MRI. All patients were analysed using a diverse range of parameters. including maximal standardized uptake value (SUV), percent change in SUV (ΔSUV), initial slope of the enhancement curve (MRslope), apparent diffusion coefficient (ADC), tumour size, change in MRslope (ΔMRslope), change in ADC (ΔADC), change in tumour size (Δsize) and other clinicopathological parameters]. The relationships between covariates and DFS after surgery were analysed using the Kaplan-Meier method and the multivariate Cox proportional hazards model. Time-dependent receiver operating characteristic curves were used to determine the optimal cut-off values of imaging parameters for DFS.

Results

Of the 54 patients, 13 (24 %) experienced recurrence at a median follow-up of 38 months (range 25 – 45 months). Univariate and multivariate analyses showed that a lesser decline in SUV, a lesser decline in MRslope, a lesser increase in ADC, and ER negativity were significantly associated with a poorer DFS (P?=?0.0006, ΔSUV threshold ?41 %; P?=?0.0016, ΔMRslope threshold ?6 %; P?=?0.011, ΔADC threshold 11 %; and P?=?0.0086, ER status, respectively). Patients with a combination of ΔSUV >?41 % and ΔMRslope >?6 % showed a significantly higher recurrence rate (77.8 %) than the remaining of patients (13.3 %, P?Conclusion Functional parameters of both FDG PET and MRI after the first cycle of NAC are useful for predicting DFS in patients with advanced breast cancer. This approach could lead to an improvement in patient care because ineffective NAC agents could be avoided and more aggressive therapy could be used in high-risk patients.     

Distinction between glioma progression and post-radiation change by combined physiologic MR imaging

Introduction

Magnetic resonance (MR) diffusion-weighted imaging (DWI), dynamic susceptibility contrast-enhanced perfusion imaging (DSC), and MR spectroscopy (MRS) techniques provide specific physiologic information that may distinguish malignant glioma progression from post-radiation change, yet no single technique is completely reliable. We propose a simple, multiparametric scoring system to improve diagnostic accuracy beyond that of each technique alone.

Methods

Fifteen subjects with lesions suspicious for glioma progression following radiation therapy who had also undergone 3-tesla DWI, DSC, and MRS studies of the lesion were retrospectively reviewed. Minimum apparent diffusion coefficient (ADC) ratio, maximum regional cerebral blood volume (rCBV) ratio, and maximum MRS choline/creatine (Cho/Cr) and choline/N-acetyl-aspartate (Cho/NAA) metabolic peak-height ratios were quantified within each lesion. Each parameter (ADC ratio, rCBV ratio, and combined Cho/Cr and Cho/NAA ratios) was scored as either glioma progression (one point) or radiation change (zero point) based upon thresholds derived from our own data. For each lesion, the combined parameters yielded a multiparametric score (0 to 3) for prediction of tumor progression or post-radiation change.

Results

Optimum thresholds for ADC ratio (1.30), rCBV ratio (2.10), and either combined Cho/Cr (1.29) and Cho/NAA (1.06) yielded diagnostic accuracies of 86.7%, 86.7%, and 84.6%, respectively (p?<?0.05). A combined multiparametric score threshold of 2 improved diagnostic accuracy to 93.3% (p?<?0.05).

Conclusion

In this small series combining 3-T DWI, DSC, and MRS diagnostic results using a simple, multiparametric scoring system has potential to improve overall diagnostic accuracy in distinguishing glioma progression from post-radiation change beyond that of each technique alone.     

MR imaging features and staging of neuroendocrine carcinomas of the uterine cervix with pathological correlations

Objective

To determine MR imaging features and staging accuracy of neuroendocrine carcinomas (NECs) of the uterine cervix with pathological correlations.

Methods

Twenty-six patients with histologically proven NECs, 60 patients with squamous cell carcinomas (SCCs), and 30 patients with adenocarcinomas of the uterine cervix were included. The clinical data, pathological findings, and MRI findings were reviewed retrospectively. MRI features of cervical NECs, SCCs, and adenocarcinomas were compared, and MRI staging of cervical NECs was compared with the pathological staging.

Results

Cervical NECs showed a higher tendency toward a homogeneous signal intensity on T2-weighted imaging and a homogeneous enhancement pattern, as well as a lower ADC value of tumour and a higher incidence of lymphadenopathy, compared with SCCs and adenocarcinomas (P?<?0.05). An ADC value cutoff of 0.90?×?10^-3 mm²/s was robust for differentiation between cervical NECs and other cervical cancers, with a sensitivity of 63.3 % and a specificity of 95 %. In 21 patients who underwent radical hysterectomy and lymphadenectomy, the overall accuracy of tumour staging by MR imaging was 85.7 % with reference to pathology staging.

Conclusion

Homogeneous lesion texture and low ADC value are likely suggestive features of cervical NECs and MR imaging is reliable for the staging of cervical NECs.

Key Points

? Cervical NECs show a tendency of lesion homogeneity and lymphadenopathy ? Low ADC values are found in cervical NECs ? MRI is an accurate imaging modality for the cervical NEC staging

     

Diffusion-weighted MR imaging in primary rectal cancer staging demonstrates but does not characterise lymph nodes

Objectives

To evaluate the performance of diffusion-weighted MRI (DWI) for the detection of lymph nodes and for differentiating between benign and metastatic nodes during primary rectal cancer staging.

Methods

Twenty-one patients underwent 1.5-T MRI followed by surgery (± preoperative 5?×?5 Gy). Imaging consisted of T2-weighted MRI, DWI (b0, 500, 1000), and 3DT1-weighted MRI with 1-mm isotropic voxels. The latter was used for accurate detection and per lesion histological validation of nodes. Two independent readers analysed the signal intensity on DWI and measured the mean apparent diffusion coefficient (ADC) for each node (ADC_node) and the ADC of each node relative to the mean tumour ADC (ADC_rel).

Results

DWI detected 6 % more nodes than T2W-MRI. The signal on DWI was not accurate for the differentiation of metastatic nodes (AUC 0.45–0.50). Interobserver reproducibility for the nodal ADC measurements was excellent (ICC 0.93). Mean ADC_node was higher for benign than for malignant nodes (1.15?±?0.24 vs. 1.04?±?0.22 *10^-3 mm²/s), though not statistically significant (P?=?0.10). Area under the ROC curve/sensitivity/specificity for the assessment of metastatic nodes were 0.64/67 %/60 % for ADC_node and 0.67/75 %/61 % for ADC_rel.

Conclusions

DWI can facilitate lymph node detection, but alone it is not reliable for differentiating between benign and malignant lymph nodes.

Key Points

? Diffusion-weighted (DW) magnetic resonance imaging (MRI) offers new information in rectal cancer. ? DW MRI demonstrates more lymph nodes than standard T2-weighted MRI. ? Visual DWI assessment does not discriminate between benign and metastatic nodes. ? Apparent diffusion coefficients do not discriminate between benign and metastatic nodes.     

Voxel-wise correlation of functional imaging parameters in HNSCC patients receiving PET/MRI in an irradiation setup

Purpose

The purpose of this study was to demonstrate the feasibility of voxel-wise multiparametric characterization of head and neck squamous cell carcinomas (HNSCC) using hybrid multiparametric magnetic resonance imaging and positron emission tomography with [¹⁸F]-fluorodesoxyglucose (FDG-PET/MRI) in a radiation treatment planning setup.

Methods

Ten patients with locally advanced HNSCC were examined with a combined FDG-PET/MRI in an irradiation planning setup. The multiparametric imaging protocol consisted of FDG-PET, T2-weighted transverse short tau inversion recovery sequence (STIR) and diffusion-weighted MRI (DWI). Primary tumours were manually segmented and quantitative imaging parameters were extracted. PET standardized uptake values (SUV) and DWI apparent diffusion coefficients (ADC) were correlated on a voxel-wise level.

Results

Images acquired in this specialised radiotherapy planning setup achieved good diagnostic quality. Median tumour volume was 4.9 [1.1–42.1]?ml. Mean PET SUV and ADC of the primary tumours were 5?±?2.5 and 1.2?±?0.3 10^?3?mm²/s, respectively. In voxel-wise correlation between ADC values and corresponding FDG SUV of the tumours, a significant negative correlation was observed (r?=??0.31?±?0.27, p?<?0.05).

Conclusion

Multiparametric voxel-wise characterization of HNSCC is feasible using combined PET/MRI in a radiation planning setup. This technique may provide novel insights into tumour biology with regard to radiation therapy in the future.

     

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.     

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     

Assessing response in bone metastases in prostate cancer with diffusion weighted MRI

Objectives

To determine whether changes in ADC of bone metastases secondary to prostate carcinoma are significantly different in responders compared with progressors on chemotherapy.

Methods

Twenty-six patients with known bone metastases secondary to prostate carcinoma underwent diffusion-weighted MRI of the lumbar spine and pelvis at baseline and 12 weeks following chemotherapy. RECIST assessment of staging CT and PSA taken at the same time points were used to classify patients as responders, progressors or stable. ADC (from b?=?0,50,100,250,500,750 smm^?2) and ADC_slow (from b?=?100,250,500,750 smm^?2) were calculated for up to 5 lesions per patient.

Results

Mean ADC/ADC_slow in lesions from responders and progressors showed a significant increase. Although the majority of lesions demonstrated an ADC/ADC_slow rise, some lesions in both responders and progressors demonstrated a fall in ADC beyond the limits of reproducibility.

Conclusions

Mean ADC is not an appropriate measure of response in bone metastases. The heterogeneity of changes in ADC is likely to be related to the composition of bone marrow with changes that have opposing effects on ADC.     

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.     

Diffusion-weighted magnetic resonance imaging: new perspectives in the diagnostic pathway of non-complicated acute pyelonephritis

Objectives

The diagnosis of acute pyelonephritis (APN) requires demonstration of parenchymal involvement. When no predisposing conditions are found, non-complicated APN is suspected and CT or MRI should be performed. Diffusion-weighted (DW) MRI might be useful, quicker and cheaper than the standard gadolinium-enhanced (GE) MRI. The aim of this study is to compare DW-MRI with GE-MRI to test its diagnostic accuracy in APN.

Methods

Of 318 consecutive patients hospitalised for APN, 279 underwent MRI. Four hundred and fourteen MR studies (first test and follow-up examinations) were gathered and data were processed using Diffusion Analysis software. DW-MRI has been compared with GE-MRI for evaluating diagnostic agreement.

Results

Two hundred and forty-four patients were diagnosed as having APN; 35 were negative. One hundred and sixty-three APN cases were considered non-complicated and selected for the study. Among the 414 MR examinations, comparing DW-MRI with GE-MRI, positive correlation was found in 258 cases, negative in 133. There were 14 false-negatives and 9 false-positives. DW-MRI achieved sensitivity 95.2 %, specificity 94.9 %, positive predictive value 96.9 %, negative predictive value 92.3 % and accuracy 94.6 %.

Conclusions

DW-MRI is reliable for diagnosing non-complicated APN. The high diagnostic agreement between DW-MRI and GE-MRI offers new perspectives in diagnostic management, enabling diagnosis of non-complicated APN without using ionising radiation or contrast media.

Key Points

? The diagnosis of acute pyelonephritis (APN) requires demonstration of renal involvement. ? Hitherto magnetic resonance imaging required gadolinium enhancement (GE-MRI) to establish this diagnosis. ? But diagnostic agreement between diffusion-weighted and GE-MRI offers new diagnostic opportunities. ? Quantification of ADC values can help diagnose and monitor APN. ? DW-MRI avoids ionising radiation and paramagnetic contrast medium administration.