Value of dynamic contrast-enhanced MRI and correlation with tumor angiogenesis in bladder cancer. AJR Am J Roentgenol. 2009;192:949-955. [PMID: 19304699 DOI: 10.2214/ajr.08.1332]

Usefulness of multiparametric MRI for local staging of bladder cancer

INTRODUCTION

Under staging and over staging are not uncommon with traditional MRI while staging bladder cancer. Current improvements in MRI technology due to addition of functional MR sequences that is, dynamic contrast-enhanced (DCE) imaging and diffusion-weighted imaging (DWI) have enhanced its clinical utility. The current study was designed to look for staging accuracy of multiparametric MRI (mp-MRI) that is, T2W + DCE + DWI, over conventional MRI.

MATERIAL AND METHODS

Forty patients with bladder cancer were included were subjected to mp-MRI on a 3T scanner with a phased array body coil. Four MR image sets that is, T2W, T2W + DCE, T2W + DWI, and T2W + DCE + DWI were interpreted. Accuracy of each image set was determined separately and was compared with the gold standard histopathological staging.

RESULT

Staging accuracy of different image set increased from T2W (55%) to DCE (72.5%) to DWI (80%). Maximum accuracy was seen in mp-MRI (T2W + DWI + DCE) (87.5%). While differentiating non muscle invasive from muscle invasive disease (⩽T1 vs ⩾T2 stage) staging accuracy increased from T2W (65%) to DCE (80%) to DWI (85%) with maximum in mp-MRI (90%).

CONCLUSION

mp-MRI offers high staging accuracy for bladder cancer.

Predictive Potential of Contrast-Enhanced MRI-Based Delta-Radiomics for Chemoradiation Responsiveness in Muscle-Invasive Bladder Cancer

Background/Objectives: Delta-radiomics involves analyzing feature variations at different acquisition time-points. This study aimed to assess the utility of delta-radiomics feature analysis applied to contrast-enhanced (CE) and non-contrast-enhanced (NE) T1-weighted images (WI) in predicting the therapeutic response to chemoradiotherapy (CRT) in patients diagnosed with muscle-invasive bladder cancer (MIBC). Methods: Forty-three patients with non-metastatic MIBC (cT2-4N0M0) who underwent partial or radical cystectomy after induction CRT were, retrospectively, reviewed. Pathological complete response (pCR) to CRT was defined as the absence of residual viable tumor cells in the cystectomy specimen. Identical volumes of interest corresponding to the index bladder cancer lesions on CE- and NE-T1WI on pre-therapeutic 1.5-T MRI were collaboratively delineated by one radiologist and one urologist. Texture analysis was performed using "LIFEx" software. The subtraction of radiological features between CE- and NE-T1WI yielded 112 delta-radiomics features, which were utilized in multiple machine-learning algorithms to construct optimal predictive models for CRT responsiveness. Additionally, the predictive performance of the radiomics model constructed using CE-T1WI alone was assessed. Results: Twenty-one patients (49%) achieved pCR. The best-performing delta-radiomics model, employing the "Extreme Gradient Boosting" algorithm, yielded an area under the receiver operating characteristic curve (AUC) of 0.85 (95% confidence interval [CI]: 0.75-0.95), utilizing four signal intensity-based delta-radiomics features. This outperformed the best model derived from CE-T1WI alone (AUC: 0.63, 95% CI: 0.50-0.75), which incorporated two morphological features and one signal intensity-based radiomics feature. Conclusions: Delta-radiomics analysis applied to pre-therapeutic CE- and NE-MRI demonstrated promising predictive ability for CRT responsiveness prior to treatment initiation.

Progress of Multiparameter Magnetic Resonance Imaging in Bladder Cancer: A Comprehensive Literature Review

Magnetic resonance imaging (MRI) has been proven to be an indispensable imaging method in bladder cancer, and it can accurately identify muscular invasion of bladder cancer. Multiparameter MRI is a promising tool widely used for preoperative staging evaluation of bladder cancer. Vesical Imaging-Reporting and Data System (VI-RADS) scoring has proven to be a reliable tool for local staging of bladder cancer with high accuracy in preoperative staging, but VI-RADS still faces challenges and needs further improvement. Artificial intelligence (AI) holds great promise in improving the accuracy of diagnosis and predicting the prognosis of bladder cancer. Automated machine learning techniques based on radiomics features derived from MRI have been utilized in bladder cancer diagnosis and have demonstrated promising potential for practical implementation. Future work should focus on conducting more prospective, multicenter studies to validate the additional value of quantitative studies and optimize prediction models by combining other biomarkers, such as urine and serum biomarkers. This review assesses the value of multiparameter MRI in the accurate evaluation of muscular invasion of bladder cancer, as well as the current status and progress of its application in the evaluation of efficacy and prognosis.

Differentiation of silent corticotroph pituitary neuroendocrine tumors (PitNETs) from non-functioning PitNETs using kinetic analysis of dynamic MRI

PURPOSE

Silent corticotroph pituitary adenomas (SCAs)/pituitary neuroendocrine tumors (PitNETs) are common non-functioning pituitary adenomas (NFAs)/PitNETs with a clinically aggressive course. This study aimed to investigate the ability of time-intensity analysis of dynamic magnetic resonance imaging (MRI) for distinguishing adrenocorticotropic hormone (ACTH)-positive SCAs and ACTH-negative SCAs from other NFAs.

MATERIALS AND METHODS

We retrospectively evaluated the dynamic MRI findings of patients with NFAs. The initial slope of the kinetic curve (slopeini) obtained by dynamic MRI for each tumor was analyzed using a modified empirical mathematical model. The maximum slope of the kinetic curve (slopemax) was obtained by geometric calculation.

RESULTS

A total of 106 patients with NFAs (11 ACTH-positive SCAs, 5 ACTH-negative SCAs, and 90 other NFAs) were evaluated. The kinetic curves of ACTH-positive SCAs had significantly lesser slopeini and slopemax compared with ACTH-negative SCAs (P = 0.040 and P = 0.001, respectively) and other NFAs (P = 0.018 and P = 0.035, respectively). Conversely, the slopeini and slopemax were significantly greater in ACTH-negative SCAs than in NFAs other than ACTH-negative SCAs (P = 0.033 and P = 0.044, respectively). In receiver operating characteristic analysis of ACTH-positive SCAs and other NFAs, the area under the curve (AUC) values for slopeini and slopemax were 0.762 and 0748, respectively. In predicting ACTH-negative SCAs, the AUC values for slopeini and slopemax were 0.784 and 0.846, respectively.

CONCLUSIONS

Dynamic MRI can distinguish ACTH-positive SCAs and ACTH-negative SCAs from other NFAs.

An Overview of Angiogenesis in Bladder Cancer

PURPOSE OF THE REVIEW

Angiogenesis plays a key role in bladder cancer (BC) pathogenesis. In the last two decades, an increasing number of publications depicting a multitude of novel angiogenic molecules and pathways have emerged. The growing complexity necessitates an evaluation of the breadth of current knowledge to highlight key findings and guide future research.

RECENT FINDINGS

Angiogenesis is a dynamic biologic process that is inherently difficult to assess. Clinical assessment of angiogenesis in BCs is advancing with the integration of image analysis systems and dynamic contrast-enhanced and magnetic resonance imaging (DCE-MRI). Tumour-associated macrophages (TAMs) significantly influence the angiogenic process, and further research is needed to assess their potential as therapeutic targets. A rapidly growing list of non-coding RNAs affect angiogenesis in BCs, partly through modulation of vascular endothelial growth factor (VEGF) activity. Vascular mimicry (VM) has been repeatedly associated with increased tumour aggressiveness in BCs. Standardised assays are needed for appropriate identification and quantification of VM channels. This article demonstrates the dynamic and complex nature of the angiogenic process and asserts the need for further studies to deepen our understanding.

Utility of Diffusion-Weighted MRI for Detection of Locally Recurrent Pancreatic Cancer After Surgical Resection

BACKGROUND. Overlapping imaging findings between local tumor recurrence and postsurgical fibrosis represent a major clinical challenge after pancreatic ductal adeno-carcinoma (PDAC) resection. OBJECTIVE. The purpose of this study was to compare the diagnostic performance of MRI with and without DWI for differentiating locally recurrent tumor and postsurgical fibrosis after PDAC resection. METHODS. This retrospective study included 66 patients (35 men, 31 women; mean age, 60.5 years) who underwent PDAC resection between January 2009 and March 2016, postoperative surveillance CT showing a soft-tissue lesion at the operative site or at the site of peripancreatic vessels, and subsequent MRI with DWI for further evaluation. CT at least 6 months after MRI served as the reference standard, with increase in size of the soft tissue by 5 mm or more differentiating locally recurrent tumor (n = 26) and postsurgical fibrosis (n = 40). Two observers in consensus evaluated MRI characteristics of the soft-tissue lesions. Two additional observers independently reviewed MRI examinations in two separate sessions (conventional MRI alone vs MRI with DWI), recording likelihood of recurrent tumor using a 1-5 scale. ROC analysis was performed, considering scores of 4 or 5 as positive. RESULTS. Subjective diffusion restriction was more common in locally recurrent tumor than postsurgical fibrosis (88.5% vs 25.0%, p = .01). Median ADC was lower for locally recurrent tumor than postsurgical fibrosis (1.3 vs 1.7 × 10-3 mm2/s, p < .001). For both observers, MRI with DWI in comparison with conventional MRI alone showed higher AUC for diagnosis of locally recurrent tumor (observer 1: 0.805 vs 0.707, p = .048; observer 2: 0.898 vs 0.637, p < .001) and higher sensitivity (observer 1: 88.5% vs 61.5%, p = .008; observer 2: 84.6% vs 42.3%, p = .001) but no difference in specificity (observer 1: 72.5% vs 80.0%, p = .08; observer 2, 95.0% vs 85.0%, p = .10). Interobserver agreement was moderate for conventional MRI (κ = 0.41) and good for conventional MRI with DWI (κ = 0.62). CONCLUSION. The addition of DWI to conventional MRI improves the differentiation of locally recurrent tumor and postsurgical fibrosis after PDAC resection, primarily because of improved sensitivity for recurrence. CLINICAL IMPACT. The findings indicate a potential role for MRI with DWI in surveillance protocols after PDAC resection.

Dynamic contrast-enhanced and diffusion-weighted MR imaging in early prediction of pathologic response to neoadjuvant chemotherapy in locally advanced gastric cancer

PURPOSE

To investigate the efficacy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the early prediction of the pathologic response to neoadjuvant chemotherapy (NAC) in patients with locally advanced gastric cancer (LAGC).

METHODS

Fifty patients with LAGC who were treated with NAC followed by radical gastrectomy were enrolled. Uncontrasted and DCE-MRI were performed within 1 week before NAC. According to tumor regression grading (TRG), patients were labeled as responders (TRG = 0 + 1) and non-responders (TRG = 2 + 3). Apparent diffusion coefficients (ADC) and DCE-MRI kinetics (K^trans, V_e, and K_ep) were compared between the two groups. Logistic regression analysis was performed to screen independent factors to predict the NAC efficacy. The relationship between MRI parameters and TRG was studied by Spearman's correlation analysis. Receiver-operating characteristic curve analyses were applied to evaluate the efficacy.

RESULTS

ADC, K^trans, and K_ep values were higher in responders than in non-responders (p < 0.05) and correlated with TRG (p < 0.05). The ADC and K_ep values were independent markers for predicting TRG. The area under the curve, sensitivities, specificities of ADC, K^trans, K_ep, and ADC + K_ep were 0.813, 0.699, 0.709, 0.886;73.64%, 65.54%, 63.21%, 70.37%; 86.47%, 54.97%, 79.47%, 95.65%; respectively. ADC + K_ep demonstrated a higher efficacy than K^trans and K_ep (p = 0.012, 0.011), but without improvement compared with ADC (p > 0.05).

CONCLUSION

Both DWI and DCE-MRI can effectively predict the pathologic response to NAC in LAGC. A combination of ADC and K_ep increased the efficacy, and ADC is the most valuable imaging parameter.

Role of multiparametric magnetic resonance imaging in the diagnosis and staging of urinary bladder cancer

Objectives

To assess the role of multiparametric magnetic resonance imaging (mp-MRI) in the diagnosis and staging of urinary bladder cancer (BC).

Materials and methods

Fifty patients diagnosed with bladder masses underwent mp-MRI study. The results of 3 image sets were analyzed and compared with the histopathological results as a reference standard: T2-weighted image (T2WI) plus dynamic contrast-enhanced (DCE), T2WI plus diffusion-weighted images (DWI), and mp-MRI, including T2WI plus DWI and DCE. The diagnostic accuracy of mp-MRI was evaluated using receiver operating characteristic curve analysis.

Results

The accuracy of T2WI plus DCE for detecting muscle invasion of BC was 79.5% with a fair agreement with histopathological examination (κ = 0.59); this percentage increased up to 88.6% using T2WI plus DWI, with good agreement with histopathological examination (κ = 0.74), whereas mp-MRI had the highest overall accuracy (95.4%) and excellent agreement with histopathological data (κ = 0.83). Multiparametric MRI can differentiate between low- and high-grade bladder tumors with a high sensitivity and specificity of 93.3% and 98.3%, respectively.

Conclusions

Multiparametric MRI is an acceptable method for the preoperative detection and accurate staging of BC, with reasonable accuracy in differentiating between low- and high-grade BC.

Multiparametric magnetic resonance imaging of plasmacytoid urothelial carcinoma with histopathological correlation: A case report

Plasmacytoid urothelial carcinomas of the bladder are rare, aggressive variants with a poor prognosis. Few reports have described the correlation of histopathological features with multiparametric magnetic resonance imaging findings in the local staging of plasmacytoid urothelial carcinoma. An 82-year-old woman with hematuria was referred to our hospital. Magnetic resonance imaging showed diffuse bladder wall thickening, with different signal intensities in the 2 layers—inner and outer. This case suggests that the presence of diffuse bladder wall thickening and varying signal intensities in the 2 layers could aid in the local staging of plasmacytoid urothelial carcinoma. A thickened bladder wall with restricted diffusion suggests tumor invasion, indicating that the tumor can invade the organ in contact with the thickened bladder wall.

Study Progress of Noninvasive Imaging and Radiomics for Decoding the Phenotypes and Recurrence Risk of Bladder Cancer

Urinary bladder cancer (BCa) is a highly prevalent disease among aged males. Precise diagnosis of tumor phenotypes and recurrence risk is of vital importance in the clinical management of BCa. Although imaging modalities such as CT and multiparametric MRI have played an essential role in the noninvasive diagnosis and prognosis of BCa, radiomics has also shown great potential in the precise diagnosis of BCa and preoperative prediction of the recurrence risk. Radiomics-empowered image interpretation can amplify the differences in tumor heterogeneity between different phenotypes, i.e., high-grade vs. low-grade, early-stage vs. advanced-stage, and nonmuscle-invasive vs. muscle-invasive. With a multimodal radiomics strategy, the recurrence risk of BCa can be preoperatively predicted, providing critical information for the clinical decision making. We thus reviewed the rapid progress in the field of medical imaging empowered by the radiomics for decoding the phenotype and recurrence risk of BCa during the past 20 years, summarizing the entire pipeline of the radiomics strategy for the definition of BCa phenotype and recurrence risk including region of interest definition, radiomics feature extraction, tumor phenotype prediction and recurrence risk stratification. We particularly focus on current pitfalls, challenges and opportunities to promote massive clinical applications of radiomics pipeline in the near future.

Preliminary Exploration of the Application of Vesical Imaging-Reporting and Data System (VI-RADS) in Post-treatment Patients With Bladder Cancer: A Prospective Single-Center Study

BACKGROUND

Vesical Imaging-Reporting and Data System (VI-RADS) has been shown to be effective in diagnosing muscle invasion of bladder cancer (BC) in primary patients.

PURPOSE

To evaluate the diagnostic efficacy of VI-RADS in a BC target population which included post-treatment patients, and to determine the repeatability.

STUDY TYPE

Prospective.

POPULATION

Seventy-three patients (42 with primary BC, 31 with post-treatment BC).

FIELD STRENGTH/SEQUENCE

3.0 T MRI with propeller fast spin-echo T₂ WI, echo planer imaging diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI).

ASSESSMENT

VI-RADS scores were independently assessed by five radiologists with different levels of experience. The diagnostic efficiency in each group (primary and post-treatment) and of each radiologist was assessed.

STATISTICAL TESTS

Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and area under the curve (AUC) in receiver operating characteristic curve analysis were calculated to evaluate VI-RADS diagnostic performance. Interobserver agreement was assessed using weighted Kappa statistics. A P value <0.05 was considered statistically significant.

RESULTS

At the corresponding cut-off, AUC values of three groups range from 0.936 to 0.947 and AUC values of five observers range from 0.901 to 0.963. There was no significant difference between the AUCs in the primary and post-treatment groups (P = 0.870). The cut-off of the whole group and the post-treatment group was ≥4, and the cut-off of the primary group was ≥3. The Kappa values of interobserver agreements range from 0.709 to 0.923.

CONCLUSIONS

After expanding the target population to include post-treatment patients, VI-RADS still has good diagnostic efficacy and repeatability. VI-RADS could potentially be a preoperative staging tool for post-treatment patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.

Usefulness of texture features of apparent diffusion coefficient maps in predicting chemoradiotherapy response in muscle-invasive bladder cancer

OBJECTIVES

To examine the usefulness of the texture analysis (TA) of apparent diffusion coefficient (ADC) maps in predicting the chemoradiotherapy (CRT) response of muscle-invasive bladder cancer (MIBC).

METHODS

We reviewed 45 MIBC patients who underwent cystectomy after CRT. CRT response was assessed through histologic evaluation of cystectomy specimens. Two radiologists determined the volume of interest for the index lesions on ADC maps of pretherapeutic 1.5-T MRI and performed TA using the LIFEx software. Forty-six texture features (TFs) were selected based on their contribution to the prediction of CRT sensitivity. To evaluate diagnostic performance, diagnostic models from the selected TFs were created using random forest (RF) and support vector machine (SVM), respectively.

RESULTS

Twenty-three patients achieved pathologic complete response (pCR) to CRT. The feature selection identified first quartile ADC (Q1 ADC), gray-level co-occurrence matrix (GLCM) correlation, and GLCM homogeneity as important in predicting CRT response. Patients who achieved pCR showed significantly lower Q1 ADC and GLCM correlation values (0.66 × 10^-3 mm²/s and 0.53, respectively) than those who did not (0.81 × 10^-3 mm²/s and 0.70, respectively; p < 0.05 for both). The AUCs of the RF and SVM models incorporating the selected TFs were 0.82 (95% confidence interval [CI]: 0.67-0.97) and 0.96 (95% CI: 0.91-1.00), respectively, and the AUC of the SVM model was better than that of the mean ADC value (0.76, 95% CI: 0.61-0.90; p = 0.0037).

CONCLUSION

TFs can serve as imaging biomarkers in MIBC patients for predicting CRT sensitivity. TAs of ADC maps can potentially optimize patient selection for CRT.

KEY POINTS

• Texture analysis of ADC maps and feature selection identified important texture features for classifying pathologic tumor response in patients with muscle-invasive bladder cancer. • The machine learning model incorporating the texture features set, which included first quartile ADC, GLCM correlation, and GLCM homogeneity, showed high performance in predicting chemoradiotherapy response. • Texture features could serve as imaging biomarkers that optimize eligible patient selection for chemoradiotherapy in muscle-invasive bladder cancer.

Hypoxia and its Modification in Bladder Cancer: Current and Future Perspectives

Radiotherapy plays an essential role in the curative treatment of muscle-invasive bladder cancer (MIBC). Hypoxia affects the response to MIBC radiotherapy, limiting radiocurability. Likewise, hypoxia influences MIBC genetic instability and malignant progression being associated with metastatic disease and a worse prognosis. Hypoxia identification in MIBC enables treatment stratification and the promise of improved survival. The most promising methods are histopathological markers such as necrosis; biomarkers of protein expression such as HIF-1α, GLUT-1 and CAIX; microRNAs; and novel mRNA signatures. Although hypoxia modification can take different forms, the gold standard remains carbogen and nicotinamide, which improve local control rates in bladder preservation and absolute overall survival with no significant increase in late toxicity. This is an exciting time for evolving therapies such as bioreductive agents, novel oxygen delivery techniques, immunotherapy and poly (ADP-ribose) polymerase 1 (PARP) inhibitors, all in development and representing upcoming trends in MIBC hypoxia modification. Whatever the future holds for hypoxia-modified radiotherapy, there is no doubt of its importance in MIBC. mRNA signatures provide an ideal platform for the selection of those with hypoxic tumours but are yet to qualified and integrated into the clinic. Future interventional trials will require biomarker stratification to ensure optimal treatment response to improve outcomes for patients with MIBC.

Imaging of Bladder Cancer: Standard Applications and Future Trends

The evolution in imaging has had an increasing role in the diagnosis, staging and follow up of bladder cancer. Conventional cystoscopy is crucial in the diagnosis of bladder cancer. However, a cystoscopic procedure cannot always depict carcinoma in situ (CIS) or differentiate benign from malignant tumors prior to biopsy. This review will discuss the standard application, novel imaging modalities and their additive role in patients with bladder cancer. Staging can be performed with CT, but distinguishing between T1 and T2 BCa (bladder cancer) cannot be assessed. MRI can distinguish muscle-invasive from non-muscle-invasive tumors with accurate local staging. Vesical Imaging-Reporting and Data System (VI-RADS) score is a new diagnostic modality used for the prediction of tumor aggressiveness and therapeutic response. Bone scintigraphy is recommended in patients with muscle-invasive BCa with suspected bony metastases. CT shows low sensitivity for nodal staging; however, PET (Positron Emission Tomography)/CT is superior and highly recommended for restaging and determining therapeutic effect. PET/MRI is a new imaging technique in bladder cancer imaging and its role is promising. Texture analysis has shown significant steps in discriminating low-grade from high-grade bladder cancer. Radiomics could be a reliable method for quantitative assessment of the muscle invasion of bladder cancer.

Diagnostic performance of 3-tesla multiparametric MRI for assessment of the bladder cancer T stage and histologic grade

Background

Preoperative staging of urinary bladder carcinomas using TNM system is crucial in the management of bladder cancer which is determined mainly by stage and grade of tumor at diagnosis. We aim to evaluate the diagnostic accuracy of multiparametric MRI (mp-MRI) for assessment of the bladder cancer T stage and histologic grade.

Results

The overall T2-WI diagnostic accuracy for the T stage was 72.3%, increased to be 87.1% for contrast-enhanced images, and 92.6% for DWI, reaching the maximum accuracy 94.5% using the combined multi-parametric MRI technique. Diagnostic accuracies of mp-MRI in differentiating superficial from muscle-invasive (91%) and organ-confined from non-organ confined tumors (92%) were superior to DW-MRI (89% and 87%), DCE-MRI (84% and 83%), and T2W-MRI (74% and 71%), respectively. The agreement between MRI findings and histopathological staging was greater in mp-MRI (k = 0.91; excellent agreement) than in DW-MRI (k = 0.77; moderate agreement), DCE-MRI (k = 0.76; substantial agreement), and T2W-MRI (k = 0.53; fair agreement).

Conclusion

Mp-MRI provides useful information for evaluating the local T stages of bladder cancer and can predict the histological grades of urinary bladder cancers with high diagnostic accuracy.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging as a Diagnostic Tool in the Assessment of Tumour Angiogenesis in Urinary Bladder Cancer

PURPOSE

The aim of study is to assess the role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and correlation with tumour angiogenesis in evaluation of urinary bladder cancer.

MATERIAL AND METHODS

The study included 81 patients with recent presumed diagnosis of bladder tumour or who came for follow up after management of histopathologically proven bladder cancer. All had DCE-MRI with time-signal intensity curve. The radiologic results then correlated with the histopathologic results using both haematoxylin and eosin stain and immuno-histochemical staining for localization and evaluation of CD34 immunoreactivity as a detector for the microvessel density (MVD) and tumour angiogenesis.

RESULTS

Seventy-one cases were pathologically proven to be malignant: 41 cases (58%) showed type III time-signal intensity curve (descending); 22 cases (31%) showed type II (plateau); and 8 cases (11%) showed type I (ascending) curve. The sensitivity of DCE-MRI in stage T1 bladder tumour was 80%; in stage T2, it was (90.9%); and in stage T3, it was (96.9%). Overall accuracy of DCE-MRI in tumour staging was 89.5% and P = .001 (significant). Values more than the cutoff value = 76.13 MVD are cystitis with sensitivity (90%), specificity (91%), and P value is .001, which is statistically highly significant.

CONCLUSION

There is a strong positive association between DCE-MRI (staging and washout slope of the time-signal intensity curve) with histopathologic grade, tumour stage, and MVD in bladder cancer. So, DCE-MRI can be used as reliable technique in preoperative predictions of tumour behavior and affect the planning of antiangiogenetic therapy.

Ultrafast Dynamic Contrast-Enhanced Breast MRI: Kinetic Curve Assessment Using Empirical Mathematical Model Validated with Histological Microvessel Density

RATIONALE AND OBJECTIVES

To evaluate whether parameters from empirical mathematical model (EMM) for ultrafast dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) correlate with histological microvessel density (MVD) in invasive breast cancer.

MATERIALS AND METHODS

Ninety-eight consecutive patients with invasive breast cancer underwent an institutional review board-approved ultrafast DCE-MRI including a pre- and 18 postcontrast whole breast ultrafast scans (3 seconds) followed by four standard scans (60 seconds) using a 3T system. Region of interest was placed within each lesion where the highest signal increase was observed on ultrafast DCE-MRI, and the increase rate of enhancement was calculated as follows: ΔS = (SIpost - SIpre)/SIpre. The kinetic curve obtained from ultrafast DCE-MRI was analyzed using a truncated EMM: ΔS(t) = A(1 - e^-αt), where A is the upper limit of the signal intensity, α (min^-1) is the rate of signal increase. The initial slope of the kinetic curve is given by Aα. Initial area under curve (AUC30) and time of initial enhancement was calculated. From the standard DCE-MRI, the initial enhancement rate (IER) and the signal enhancement ratio (SER) were calculated as follows: IER = (SIearly - SIpre)/SIpre, SER = (SIearly - SIpre)/(SIdelayed - SIpre). The parameters were compared to MVD obtained from surgical specimens.

RESULTS

A, α, Aα, AUC30, and time of initial enhancement significantly correlated with MVD (r = 0.29, 0.40, 0.51, 0.43, and -0.32 with p = 0.0027, p < 0.0001, p < 0.0001, p < 0.0001, and p = 0.0012, respectively), whereas IER and SER from standard DCE-MRI did not.

CONCLUSION

The parameters of the EMM, especially the initial slope or Aα, for ultrafast DCE-MRI correlated with MVD in invasive breast cancer.

Radiomics-guided therapy for bladder cancer: Using an optimal biomarker approach to determine extent of bladder cancer invasion from t2-weighted magnetic resonance images

Background

Current clinical staging methods are unable to accurately define the extent of invasion of localized bladder cancer, which affects the proper use of systemic therapy, surgery, and radiation. Our purpose was to test a novel radiomics approach to identify optimal imaging biomarkers from T2-weighted magnetic resonance imaging (MRI) scans that accurately classify localized bladder cancer into 2 tumor stage groups (≤T2 vs >T2) at both the patient level and within bladder subsectors.

Method and Materials

Preoperative T2-weighted MRI scans of 65 consecutive patients followed by radical cystectomy were identified. A 3-layer, shell-like volume of interest (VOI) was defined on each MRI slice: Inner (lumen), middle (bladder wall), and outer (perivesical tissue). An optimal biomarker method was used to identify features from 15,834 intensity and texture properties that maximized the classification of patients into ≤T2 versus >T2 groups. A leave-one-out strategy was used to cross-validate the performance of the identified biomarker feature set at the patient level. The performance of the feature set was then evaluated at the subsector level of the bladder by dividing the VOIs into 8 radial sectors.

Results

A total of 9 optimal biomarker features were derived and demonstrated a sensitivity, specificity, accuracy of prediction, and area under a receiver operating characteristic curve of 0.742, 0.824, 0.785, and 0.806, respectively, at the patient level and 0.681, 0.788, 0.763, and 0.813, respectively, at the radial sector level. All 9 selected features were extracted from the middle shell of the VOI and based on texture properties.

Conclusions

An approach to select a small, highly independent feature set that is derived from T2-weighted MRI scans that separate patients with bladder cancer into ≤T2 versus >T2 groups at both the patient level and within subsectors of the bladder has been developed and tested. With external validation, this radiomics approach could improve the clinical staging of bladder cancer and optimize therapeutic management.

Differentiation between high- and low-grade urothelial carcinomas using contrast enhanced ultrasound

Purpose

To evaluate the value of contrast-enhanced ultrasonography (CEUS) in the differentiation of high and low grade urothelial carcinoma.

Materials and Methods

192 with 192 bladder lesions, including 110 high grade urothelial carcinoma and 82 low grade urothelial carcinoma were examined by CEUS. Among 192 tumors, enhancement patterns of 96 tumors between August 2010 and December 2012 were analyzed retrospectively. Then from January 2013 to April 2015, compared with CEUS was performed on 96 tumors for prospective differential diagnosis. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value were assessed.

Results

With the CEUS view, dominant enhancement patterns were revealed as fast wash-in and slow wash-out for high grade urothelial carcinoma, fast wash-in and fast wash-out for low grade urothelial carcinoma, respectively. At CEUS, the prospective differentiation of bladder tumors showed sensitivity 86% , specificity 90%, accuracy 88%, positive predictive value 92%, and negative predictive value 82% for high grade tumors, while sensitivity 85% , specificity 89%, accuracy 88%, positive predictive value 85% and negative predictive value 89% for low grade tumors, respectively.

Conclusions

Our study demonstrates the great potential of CEUS in the differentiation of high and low grade urothelial carcinoma. Since CEUS is an effective, inexpensive, and non-invasive method. It could be a reliable tool in the evaluation of patients with bladder tumors.

Role of Multiparametric MR Imaging in Malignancies of the Urogenital Tract

Multiparametric MR imaging (mpMRI) combine different sequences that, properly tailored, can provide qualitative and quantitative information about the tumor microenvironment beyond traditional tumor size measures and/or morphologic assessments. This article focuses on mpMRI in the evaluation of urogenital tract malignancies by first reviewing technical aspects and then discussing its potential clinical role. This includes insight into histologic subtyping and grading of renal cell carcinoma and assessment of tumor response to targeted therapies. The clinical utility of mpMRI in the staging and grading of ureteral and bladder tumors is presented. Finally, the evolving role of mpMRI in prostate cancer is discussed.

Improving Staging in Bladder Cancer: The Increasing Role of Multiparametric Magnetic Resonance Imaging

CONTEXT

In bladder cancer (BCa) patients, accurate local and regional tumor staging is required when planning treatment. Clinical understaging frequently occurs and leads to undertreatment of the disease, with a negative impact on survival. An improvement in staging accuracy could be attained by advances in imaging. Magnetic resonance imaging (MRI) is currently the best imaging technique for locoregional staging for several malignancies because of its superior soft tissue contrast resolution with the advantage of avoiding exposure to ionizing radiation. Important improvements in MRI technology have led to the introduction of multiparametric MRI (mpMRI), which combines anatomic and functional evaluation.

OBJECTIVE

To review the fundamentals of mpMRI in BCa and to provide a contemporary overview of the available data on the role of this emerging imaging technology.

EVIDENCE ACQUISITION

A nonsystematic literature search using the Medline and Cochrane Library databases was performed up to March 2016. Additional articles were retrieved by cross-matching references of selected articles. Only articles reporting complete data with regard to image acquisition protocols, locoregional staging, monitoring response to therapy, and detection of locoregional recurrence after primary treatment in BCa patients were selected.

EVIDENCE SYNTHESIS

Standardization of acquisition and reporting protocols for bladder mpMRI is paramount. Combining anatomic and functional sequences improves the accuracy of local tumor staging compared with conventional imaging alone. Diffusion-weighted imaging may distinguish BCa type and grade. Functional sequences are capable of monitoring response to chemotherapy and radiation therapy. Diffusion-weighted imaging enhanced by lymphotropic nanoparticles showed high accuracy in pelvic lymph node staging compared with conventional cross-sectional imaging.

CONCLUSIONS

In BCa patients, mpMRI appears a promising tool for accurate locoregional staging, predicting tumor aggressiveness and monitoring response to therapy. Further large-scale studies are needed to confirm these findings.

PATIENT SUMMARY

Better imaging through improved technology will improve outcomes in bladder cancer patients. We reviewed the emerging use of multiparametric magnetic resonance imaging for staging and monitoring bladder cancer. Multiparametric magnetic resonance imaging appears more accurate than current methods for local and nodal staging and monitoring tumor response to treatment, but requires further investigation.

Comparison of Coregistration Accuracy of Pelvic Structures Between Sequential and Simultaneous Imaging During Hybrid PET/MRI in Patients with Bladder Cancer

PURPOSE

The aim of this study was to compare coregistration of the bladder wall, bladder masses, and pelvic lymph nodes between sequential and simultaneous PET and MRI acquisitions obtained during hybrid (18)F-FDG PET/MRI performed using a diuresis protocol in bladder cancer patients.

METHODS

Six bladder cancer patients underwent (18)F-FDG hybrid PET/MRI, including IV Lasix administration and oral hydration, before imaging to achieve bladder clearance. Axial T2-weighted imaging (T2WI) was obtained approximately 40 minutes before PET ("sequential") and concurrently with PET ("simultaneous"). Three-dimensional spatial coordinates of the bladder wall, bladder masses, and pelvic lymph nodes were recorded for PET and T2WI. Distances between these locations on PET and T2WI sequences were computed and used to compare in-plane (x-y plane) and through-plane (z-axis) misregistration relative to PET between T2WI acquisitions.

RESULTS

The bladder increased in volume between T2WI acquisitions (sequential, 176 [139] mL; simultaneous, 255 [146] mL). Four patients exhibited a bladder mass, all with increased activity (SUV, 9.5-38.4). Seven pelvic lymph nodes in 4 patients showed increased activity (SUV, 2.2-9.9). The bladder wall exhibited substantially less misregistration relative to PET for simultaneous, compared with sequential, acquisitions in in-plane (2.8 [3.1] mm vs 7.4 [9.1] mm) and through-plane (1.7 [2.2] mm vs 5.7 [9.6] mm) dimensions. Bladder masses exhibited slightly decreased misregistration for simultaneous, compared with sequential, acquisitions in in-plane (2.2 [1.4] mm vs 2.6 [1.9] mm) and through-plane (0.0 [0.0] mm vs 0.3 [0.8] mm) dimensions. FDG-avid lymph nodes exhibited slightly decreased in-plane misregistration (1.1 [0.8] mm vs 2.5 [0.6] mm), although identical through-plane misregistration (4.0 [1.9] mm vs 4.0 [2.8] mm).

CONCLUSIONS

Using hybrid PET/MRI, simultaneous imaging substantially improved bladder wall coregistration and slightly improved coregistration of bladder masses and pelvic lymph nodes.

Performance of simultaneous high temporal resolution quantitative perfusion imaging of bladder tumors and conventional multi-phase urography using a novel free-breathing continuously acquired radial compressed-sensing MRI sequence

PURPOSE

To investigate the feasibility of high temporal resolution quantitative perfusion imaging of bladder tumors performed simultaneously with conventional multi-phase MR urography (MRU) using a novel free-breathing continuously acquired radial MRI sequence with compressed-sensing reconstruction.

METHODS

22 patients with bladder lesions underwent MRU using GRASP (Golden-angle RAdial Sparse Parallel) acquisition. Multi-phase contrast-enhanced abdominopelvic GRASP was performed during free-breathing (1.4×1.4×3.0mm(3) voxel size; 3:44min acquisition). Two dynamic datasets were retrospectively reconstructed by combining different numbers of sequentially acquired spokes into each dynamic frame: 110 spokes per frame for 25-s temporal resolution (serving as conventional MRU for clinical interpretation) and 8 spokes per frame for 1.7-s resolution. Using 1.7-s resolution images, ROIs were placed within bladder lesions and normal bladder wall, a femoral artery arterial input function was generated, and the Generalized Kinetic Model was applied.

RESULTS

Biopsy/cystectomy demonstrated 16 bladder tumors (13 stage≥T2, 3 stage≤T1) and 6 benign lesions. All lesions were well visualized using 25-s clinical multi-phase images. Using 1.7-s resolution images, K(trans) was significantly higher in tumors (0.38±0.24) than normal bladder (0.12±0.02=8, p<0.001) or benign lesions (0.15±0.04, p=0.033). Ratio between K(trans) of lesions and normal bladder was nearly double for tumors than benign lesions (4.3±3.4 vs. 2.2±1.6), and K(trans) was nearly double in stage≥T2 than stage≤T1 tumors (0.44±0.24 vs. 0.24±0.24), although these did not approach significance (p=0.180-0.209), possibly related to small sample size.

CONCLUSION

GRASP allows simultaneous quantitative high temporal resolution perfusion of bladder lesions during clinical MRU examinations using only one contrast injection and without additional scan time.

Dynamic contrast-enhanced MRI of ocular melanoma

Dynamic contrast-enhanced MRI is used for the assessment of microvasculature in several tumours. We aimed to assess the contrast signal enhancement characteristics of ocular melanoma. Forty patients with ocular melanoma were prospectively investigated with ocular MRI including dynamic contrast-enhanced sequences over a 13-month period. A region-of-interest analysis of the images was carried out to calculate signal enhancement characteristics after a contrast injection. Clinical follow-up data such as extraocular spread and development of liver metastasis were compared with the signal enhancement characteristics of the ocular melanoma. In 39 patients (98%), the ocular melanomas showed an early strong signal enhancement after contrast injection, resulting in a mean time of maximum enhancement of 49 s. Clinical follow-up was available in 28 patients (70%) and indicated that the peak signal intensity was significantly increased (P=0.039) in patients who developed extraocular spread or liver metastasis at a later stage. Ocular melanoma shows signal enhancement characteristics of hypervascular neoplasms. This study provides baseline curve pattern data that may be useful for assessing changes in vascularity, for example during therapy response. Furthermore, the study showed that a strong signal enhancement of the ocular melanoma might be linked to a less favourable prognosis.

Combining dynamic contrast enhanced magnetic resonance imaging and microvessel density to assess the angiogenesis after PEI in a rabbit VX2 liver tumor model

OBJECTIVES

To evaluate the correlation between parameters of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) and microvessel density (MVD) measurements in rabbit VX2 liver tumor models after percutaneous ethanol injection (PEI) and to observe influence of PEI on angiogenesis in a rabbit VX2 liver tumor model with dynamic contrast enhanced magnetic resonance imaging (DCE-MRI).

MATERIALS AND METHODS

Forty five New Zealand white rabbits were used in this study. VX2 tumor tissue blocks were implanted in the left lobe of liver by percutaneous puncture under CT guidance. 2 weeks later, all rabbits underwent conventional MRI (T1WI, T2WI) to determine the successful models. Then those successful implanted VX2 liver tumor models in the study were randomly divided into the control group and the experimental group, the former did not have processing, and the latter underwent PEI under CT guidance. MRI (T1WI, T2WI and DCE-MRI) was performed 1 week later again, the parameters of DCE-MRI (Ktrans, Kep, Ve and iAUC60) of viable tumor portions were observed. Then all the liver samples were processed for hematoxylin and eosin (H&E) staining and immunohistochemical staining for CD31 to determine MVD. At last, data (including DCE-MRI perfusion parameters and MVD) were compared between experimental and control groups, correlation of DCE-MRI perfusion parameters and MVD was evaluated.

RESULTS

Twenty six VX2 liver tumor models underwent all examinations (thirteen models for each group) 1 week later after PEI. For the experimental group, the parameters Ktrans (r=0.6382, P=0.0189) and iAUC60 (r=0.6591, P=0.0143) in viable tumor portions were positively moderately correlated with MVD, whereas the parameters Kep (r=0.4656, P=0.1088) and Ve (r=0.2918, P=0.3333) were not correlated with MVD. For the control group, the parameters Ktrans (r=0.6385, P=0.0188) and iAUC60 (r=0.6391, P=0.0187) in viable tumor portions were also positively moderately correlated with MVD, while the parameters Kep (r=0.5518, P=0.0506) and Ve (r=-0.0824, P=0.789) were not correlated with MVD. Ktrans, Kep, Ve, iAUC60 and MVD of residual viable tumors in the experimental group 1 week later after PEI were similar to the viable tumors of the control group (P>0.05).

CONCLUSIONS

DCE-MRI could be used to evaluate the efficiency of VX2 liver tumor after PEI. The quantitative parameter Ktrans and semi-quantitative parameter iAUC60 of DCE-MRI are correlated with MVD, which can assess tumor angiogenesis noninvasively of VX2 liver tumor model, and ethanol has no significant impact on angiogenesis of viable tumor 1week later after PEI.

Progressing Toward a Cohesive Pediatric 18F-FDG PET/MR Protocol: Is Administration of Gadolinium Chelates Necessary?

With the increasing availability of integrated PET/MR scanners, the utility and need for MR contrast agents for combined scans is questioned. The purpose of our study was to evaluate whether administration of gadolinium chelates is necessary for evaluation of pediatric tumors on (18)F-FDG PET/MR images.

METHODS

First, in 119 pediatric patients with primary and secondary tumors, we used 14 diagnostic criteria to compare the accuracy of several MR sequences: unenhanced T2-weighted fast spin-echo imaging; unenhanced diffusion-weighted imaging; and-before and after gadolinium chelate contrast enhancement-T1-weighted 3-dimensional spoiled gradient echo LAVA (liver acquisition with volume acquisition) imaging. Next, in a subset of 36 patients who had undergone (18)F-FDG PET within 3 wk of MRI, we fused the PET images with the unenhanced T2-weighted MR images (unenhanced (18)F-FDG PET/MRI) and the enhanced T1-weighted MR images (enhanced (18)F-FDG PET/MRI). Using the McNemar test, we compared the accuracy of the two types of fused images using the 14 diagnostic criteria. We also evaluated the concordance between (18)F-FDG avidity and gadolinium chelate enhancement. The standard of reference was histopathologic results, surgical notes, and follow-up imaging.

RESULTS

There was no significant difference in diagnostic accuracy between the unenhanced and enhanced MR images. Accordingly, there was no significant difference in diagnostic accuracy between the unenhanced and enhanced (18)F-FDG PET/MR images. (18)F-FDG avidity and gadolinium chelate enhancement were concordant in 30 of the 36 patients and 106 of their 123 tumors.

CONCLUSION

Gadolinium chelate administration is not necessary for accurate diagnostic characterization of most solid pediatric malignancies on (18)F-FDG PET/MR images, with the possible exception of focal liver lesions.

Optimal combination of antiangiogenic therapy for hepatocellular carcinoma

The success of sorafenib in prolonging survival of patients with hepatocellular carcinoma (HCC) makes therapeutic inhibition of angiogenesis a component of treatment for HCC. To enhance therapeutic efficacy, overcome drug resistance and reduce toxicity, combination of antiangiogenic agents with chemotherapy, radiotherapy or other targeted agents were evaluated. Nevertheless, the use of antiangiogenic therapy remains suboptimal regarding dosage, schedule and duration of therapy. The issue is further complicated by combination antiangiogenesis to other cytotoxic or biologic agents. There is no way to determine which patients are most likely respond to a given form of antiangiogenic therapy. Activation of alternative pathways associated with disease progression in patients undergoing antiangiogenic therapy has also been recognized. There is increasing importance in identifying, validating and standardizing potential response biomarkers for antiangiogenesis therapy for HCC patients. In this review, biomarkers for antiangiogenesis therapy including systemic, circulating, tissue and imaging ones are summarized. The strength and deficit of circulating and imaging biomarkers were further demonstrated by a series of studies in HCC patients receiving radiotherapy with or without thalidomide.

Comparison of dynamic contrast-enhanced and diffusion weighted magnetic resonance image in staging and grading of carcinoma bladder with histopathological correlation

BACKGROUND

Bladder cancer is the second most common neoplasm of the urinary tract worldwide. Dynamic contrast-enhanced and diffusion-weighted MRI has been introduced in clinical MRI protocols of bladder cancer because of its accuracy in staging and grading.

AIM

To evaluate and compare accuracy of Dynamic contrast enhanced (DCE) and Diffusion weighted (DW) MRI for preoperative T staging of urinary bladder cancer and find correlation between apparent diffusion coefficient (ADC) and maximum enhancement with histological grade.

MATERIALS AND METHODS

Sixty patients with bladder cancer were included in study. All patients underwent Magnetic Resonance Imaging (MRI) on a 1.5-T scanner with a phased-array pelvic coil. MR images were evaluated and assigned a stage which was compared with the histolopathological staging. ADC value and maximum enhancement curve were used based on previous studies. Subsequently histological grade was compared with MR characteristics.

RESULTS

The extent of agreement between the radiologic staging and histopathological staging was relatively greater with the DW-MRI (κ=0.669) than DCE-MRI (κ=0.619). The sensitivity, specificity, and accuracy are maximum and similar for stage T4 tumors in both DCEMRI (100.0, 96.2 and 96.7) and DW-MRI (100.0, 96.2 and 96.7) while minimum for stage T2 tumors - DCEMRI (83.3, 72.2, and 76.7) and DWI-MRI (91.7, 72.2, and 80).

CONCLUSION

MRI is an effective tool for determining T stage and histological grade of urinary bladder cancers. Stage T2a and T2b can be differentiated only by DCE-MRI. Results were more accurate when both ADC and DCE-MRI were used together and hence a combined approach is suggested.

Usefulness of dynamic MRI enhancement measures for the diagnosis of ACTH-producing pituitary adenomas

PURPOSE

The distinction between corticotropin (ACTH)-producing pituitary adenomas and occult ectopic ACTH neoplasms is a challenge and frequently complicated by the detection of nonfunctioning pituitary adenomas on dynamic magnetic resonance imaging (DMRI). Herein, we explored quantitative differences in DMRI measures from ACTH-producing pituitary adenomas.

MATERIALS AND METHODS

Fifty-five patients with pathology confirmed ACTH-producing and 44 with nonfunctioning pituitary adenomas were analysed in this retrospective pilot study. The intensities of adenomas and of adjacent pituitary tissue were measured by drawing a region of interest. Time-intensity curves were then constructed, and quantitative analysis included: enhancement time, enhancement peak and prepeak slope (PPS). Multivariable logistic analysis and receiver operating characteristic curves (ROC) were used to evaluate the parameters.

RESULTS

Quantitative analysis showed that tumour PPS in ACTH-producing adenomas was markedly lower than that in nonfunctioning adenomas (P = 0·0042) and that the PPS of the adjacent pituitary gland was not different (P = 0·2441). The PPS was >3·0 in 59·1% of nonfunctioning adenomas and ≤3·0 in 69·1% of ACTH-producing adenomas (P = 0·0049). Logistic analysis revealed lower tumour PPS levels (P = 0·0123, OR 1·24, 95% CI: 1·05-1·52) were associated with ACTH-producing adenomas. The optimal PPS cut-off determined by ROC analysis was 2·89, with a sensitivity of 69% and specificity of 70%. No significant difference was found between the two groups in enhancement time or enhancement peak.

CONCLUSION

Enhancement parameters in DMRI can help distinguishing ACTH producing from nonfunctioning pituitary adenomas, which could be useful in the differential diagnosis between ACTH-producing pituitary adenomas and ectopic ACTH syndrome complicated with nonfunctioning pituitary adenoma.

Magnetic resonance-imaging of the effect of targeted antiangiogenic gene delivery in a melanoma tumour model

OBJECTIVES

We investigated the effect of targeted gene therapy to melanoma tumours (M21) by MR-imaging.

METHODS

M21 and M21-L tumours were grown to a size of 850 mm(3). M21 and M21-L tumours were intravenously treated with an αvβ3-integrin-ligand-coupled nanoparticle (RGDNP)/RAF(-) complex five times every 72 hours. MRI was performed at set time intervals 24h and 72h after the i.v. injection of the complex. The MRI protocol was T1-wt-SE±CM, T2-wt-FSE, DCE-MRI, Diffusion-wt-STEAM-sequence, T2-time obtained on a 1.5-T-GE-MRI device.

RESULTS

The size of the treated M21 tumours kept nearly constant during the treatment phase (847.8±31.4 mm(3) versus 904.8±44.4 mm(3)). The SNR value (T2-weighted images) of the tumours was 36.7±0.6 and dropped down to 30.6±1.9 (p=0.004). At the beginning the SNR value (T1-weighted images) of the tumours after contrast medium application was 42.3±1.9 and dropped down to 28.5±3.0 (p<0.001). In the treatment group the diffusion coefficient increased significantly under therapy (0.54±0.01x10(-3) mm(2)/s versus 0.67±0.04x10(-3) mm(2)/s). The DCE-MRI showed a reduction of the slope and of the Akep of 67.8±4.3 % respectively 64.8±3.3 % compared to baseline.

CONCLUSIONS

Targeted gene delivery therapy induces significant changes in MR-imaging. MRI showed a significant reduction of contrast medium uptake parameters and increase of the diffusion coefficient of the tumours.

KEY POINT

• Treatment with targeted gene-delivery therapy can be monitored by MR imaging • DCE and diffusion-weighted imaging are appropriate methods for monitoring this therapy • Functional changes are significant prior to any morphological changes.

DCE-MRI defined subvolumes of a brain metastatic lesion by principle component analysis and fuzzy-c-means clustering for response assessment of radiation therapy

PURPOSE

To develop a pharmacokinetic modelfree framework to analyze the dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data for assessment of response of brain metastases to radiation therapy.

METHODS

Twenty patients with 45 analyzable brain metastases had MRI scans prior to whole brain radiation therapy (WBRT) and at the end of the 2-week therapy. The volumetric DCE images covering the whole brain were acquired on a 3T scanner with approximately 5 s temporal resolution and a total scan time of about 3 min. DCE curves from all voxels of the 45 brain metastases were normalized and then temporally aligned. A DCE matrix that is constructed from the aligned DCE curves of all voxels of the 45 lesions obtained prior to WBRT is processed by principal component analysis to generate the principal components (PCs). Then, the projection coefficient maps prior to and at the end of WBRT are created for each lesion. Next, a pattern recognition technique, based upon fuzzy-c-means clustering, is used to delineate the tumor subvolumes relating to the value of the significant projection coefficients. The relationship between changes in different tumor subvolumes and treatment response was evaluated to differentiate responsive from stable and progressive tumors. Performance of the PC-defined tumor subvolume was also evaluated by receiver operating characteristic (ROC) analysis in prediction of nonresponsive lesions and compared with physiological-defined tumor subvolumes.

RESULTS

The projection coefficient maps of the first three PCs contain almost all response-related information in DCE curves of brain metastases. The first projection coefficient, related to the area under DCE curves, is the major component to determine response while the third one has a complimentary role. In ROC analysis, the area under curve of 0.88 ± 0.05 and 0.86 ± 0.06 were achieved for the PC-defined and physiological-defined tumor subvolume in response assessment.

CONCLUSIONS

The PC-defined subvolume of a brain metastasis could predict tumor response to therapy similar to the physiological-defined one, while the former is determined more rapidly for clinical decision-making support.

Imaging tumor angiogenesis: the road to clinical utility

OBJECTIVE

Tumor growth and progression require the formation of new blood vessels from preexisting vasculature, a process called angiogenesis. The ability to noninvasively visualize angiogenesis may provide new opportunities to more appropriately select patients for antiangiogenesis treatment and to monitor treatment efficacy.

CONCLUSION

The superior molecular sensitivity of PET and the lack of radiation from MRI and contrast-enhanced ultrasound put these techniques at the forefront of clinical translation.

Dynamic contrast-enhanced MRI in patients with muscle-invasive transitional cell carcinoma of the bladder can distinguish between residual tumour and post-chemotherapy effect

INTRODUCTION

Treatment of muscle-invasive bladder cancer with chemotherapy results in haemorrhagic inflammation, mimicking residual tumour on conventional MR images and making interpretation difficult. The aim of this study was to use dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to estimate descriptive and tracer kinetic parameters post-neoadjuvant chemotherapy and to investigate whether parameters differed in areas of residual tumour and chemotherapy-induced haemorrhagic inflammation (treatment effect, Tr-Eff).

METHODS AND MATERIALS

Twenty-one patients underwent DCE-MRI scans with 2.5s temporal resolution before and following neoadjuvant chemotherapy. Regions-of-interest (ROIs) were defined in areas suspicious of residual tumour on T2-weighted MRI scans. Data were analysed semi-quantitatively and with a two-compartment exchange model to obtain parameters including relative signal intensity (rSI80s) and plasma perfusion (Fp) respectively. The bladder was subsequently examined histologically after cystectomy for evidence of residual tumour and/or Tr-Eff. Differences in parameters measured in areas of residual tumour and Tr-Eff were examined using Student's t-test.

RESULTS

Twenty-four abnormal sites were defined after neoadjuvant chemotherapy. On pathology, 10 and 14 areas were identified as residual tumour and Tr-Eff respectively. Median rSI80s and Fp were significantly higher in areas of residual tumour than Tr-Eff (rSI80s = 2.9 vs 1.7, p < 0.001; Fp = 20.7 vs 9.1 ml/100ml/min, p = 0.03). The sensitivity and specificity for differentiating residual tumour from Tr-Eff were 70% and 100% (rSI80s), 60% and 86% (Fp), and 75% and 100% when combined.

CONCLUSION

DCE-MRI parameters obtained post-treatment are capable of distinguishing between residual tumour and treatment effect in patients treated for bladder cancer with neoadjuvant chemotherapy.

Current Staging Procedures in Urinary Bladder Cancer

Currently computed tomography (CT) represents the most widely used standard imaging modality in muscle-invasive urinary bladder cancer. Visualization of local tumor or depth of invasion as well as lymph node staging, however, is often impaired. Magnetic resonance imaging (MRI) with diffusion-weighted sequences, determination of apparent diffusion coefficient (ADC) values or utilization of superparamagnetic iron nanoparticles potentially exhibits advantages in the assessment of local tumor or lymph node involvement and therefore might play a role in routine staging of urinary bladder cancer in the future. Likewise, positron emission tomography (PET) with the currently utilized tracers ¹⁸F-FDG, ¹¹C-choline and ¹¹C-acetate is investigated in bladder cancer patients—mostly in combination with diagnostic CT. Although promising results could be obtained for these PET/CT examinations in smaller series, their true value cannot be determined at present.

Tumor perfusion-related parameter of diffusion-weighted magnetic resonance imaging: correlation with histological microvessel density

PURPOSE

We obtained intravoxel incoherent motion (IVIM) parameters through biexponential analysis on diffusion-weighted MR imaging (DWI) using multiple b values. Correlation was evaluated between these parameters and histological microvessel density (MVD) for the possibility of noninvasive evaluation of MVD with DWI.

METHODS

Twenty-five nude mice with the HT29 colorectal cancer cells implanted were analyzed after undergoing DWI with multiple b values (0, 50, 100, 300, 500, 700, and 1000 s/mm(2)). Tissue diffusivity (D(t)), pseudo-diffusion coefficient (D(p)), and perfusion fraction (f(p)) were calculated using a biexponential analysis, and these parameters were correlated with MVD. The MVD was determined with the CD31 stain. For statistical analysis, Spearman's rank correlation was applied.

RESULTS

The mean value and correlation coefficient with MVD for each IVIM parameter were as follows: D(t)  = 0.98 ± 0.06 × 10(-3) mm(2)/s with r = 0.139 (P = 0.508); D(p) = 23.70 ± 7.94 × 10(-3) mm(2)/s with r = 0.782 (P < 0.001); and f(p) = 15.58 ± 5.7% with r = 0.749 (P < 0.001). D(p) and f(p) showed significant correlation with MVD, but D(t) did not.

CONCLUSION

The IVIM parameters, D(p) and f(p), on DWI might be used in the noninvasive evaluation of MVD.

Dynamic contrast-enhanced magnetic resonance imaging for characterising nasopharyngeal carcinoma: comparison of semiquantitative and quantitative parameters and correlation with tumour stage

OBJECTIVES

To evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for characterising nasopharyngeal carcinoma (NPC).

METHODS

Forty-five newly diagnosed NPC patients were recruited. The initial enhancement rate (E R ), contrast transfer rate (k ep ), elimination rate (k el ), maximal enhancement (MaxEn) and initial area under the curve (iAUC) were calculated from semiquantitative analysis. The K (trans) (volume transfer constant), v e (volume fraction) and k ep were calculated from quantitative analysis. Student's t-test was used to evaluate the differences among tumour stages. Pearson's correlation between the two sets of k ep was performed.

RESULTS

Comparing tumours of T1/2 stage (n = 18) and T3/4 stage (n = 27), MaxEn (P = 0.030) and iAUC (P = 0.039) were both significantly different; however, the iAUC was the only independent variable with 69.6 % sensitivity and 76.5 % specificity respectively; v e was also significantly different (P = 0.010) with 69.6 % sensitivity and 70.6 % specificity respectively. No significant difference was found among N stages. The two sets of k ep s were highly correlated (r = 0.809, P < 0.001). Forty-three patients had chemoradiation, one palliative chemotherapy and one radiotherapy only. In the four patients with poor outcome, k el, E R, MaxEn and iAUC tended to be higher.

CONCLUSIONS

Neovasculature in higher T stage NPC exhibits some parameters of increased permeability and perfusion. Thus, DCE-MRI may be helpful as an adjunctive technique in evaluating NPC.

KEY POINTS

• The correct assessment of nasopharyngeal carcinoma (NPC) is important for planning treatment. • Neovasculature in higher T stage NPC exhibits increased permeability and perfusion. • Correlation between quantitative and semi-quantitative analysis validates the robustness of DCE-MRI. • DCE-MRI may be helpful as an adjunctive parameter in evaluating NPC.

Dynamic contrast-enhanced subtraction MRI for characterizing intratesticular mass lesions

OBJECTIVE

The objective of our study was to analyze the enhancement patterns of various intratesticular mass lesions at dynamic contrast-enhanced subtraction MRI and assess the value of the technique in distinguishing between benign and malignant lesions.

MATERIALS AND METHODS

We retrospectively evaluated the records and images of 44 consecutive men (11 benign and 16 malignant intratesticular lesions) who presented to the department of urology with a variety of clinical symptoms and were referred for imaging. Dynamic contrast-enhanced subtraction MRI was performed using a 3D fast-field echo sequence after the administration of paramagnetic contrast medium. Patients were divided into three groups according to the final diagnosis: benign intratesticular lesions, malignant intratesticular lesions, and normal testes. The patterns of contrast enhancement of both the normal testes and the intratesticular lesions were evaluated. Time-signal intensity plots were created and classified according to shape: Type I presented a linear increase of contrast enhancement throughout the examination, type II showed an initial upstroke followed by either a plateau or a gradual increase in the late contrast-enhanced phase, and type III presented an initial upstroke followed by gradual washout of the contrast medium. The relative percentages of peak height, maximum time, and mean slope were also calculated.

RESULTS

Normal testes enhanced homogeneously with a type I curve. Most benign intratesticular lesions showed inhomogeneous or homogeneous contrast enhancement and a type II curve. Testicular carcinomas showed heterogeneous contrast enhancement with a type III curve. The relative percentages of maximum time to peak proved the most important discriminating factor in differentiating malignant from benign intratesticular masses (p < 0.001).

CONCLUSION

Dynamic contrast-enhanced MRI may be used to distinguish between benign and malignant intratesticular mass lesions.

Long-term survival and onset of granulomatous pneumonia after lung metastasectomy in a patient with non-muscle-invasive bladder cancer

AIMS

This case report describes a first case of granulomatous pneumonia occurring at the same site of the previous lung metastasectomy in a patient with high-grade non-muscle-invasive bladder cancer (NMIBC), which was treated with bladder preservation therapy despite multiple recurrences and failure of intravesical bacillus Calmette-Guẻrin (BCG) therapy.

CLINICAL CASE

We report a 52-year-old woman who underwent transurethral surgery and BCG therapy for pT1, G3 bladder cancer. Although cystectomy was recommended after BCG failure, the operation was not performed because of the patient's wish for bladder preservation. Eighteen months after the first surgery, computed tomography (CT) revealed solitary lung mass. Partial lobectomy which the patient underwent after chemotherapy revealed G3 metastatic urothelial carcinoma. Three years after lung metastasectomy, CT revealed lung mass at the same site of the previous lung metastasectomy. Dynamic contrast-enhanced magnetic resonance imaging showed the significantly enhanced lung mass, which indicated lung metastasis. However, lobectomy of the remnant lobe revealed that the lung mass was granulomatous pneumonia. Although no additional specific treatment was carried out, the patient remains free of disease for 53 months after surgery.

CONCLUSIONS

Lung metastasis from NMIBC rarely occurs. Our case report confirms that lung metastasectomy in highly selected patients may contribute to long-term disease control. Moreover, our case report suggests that mycobacterial lung infections along the staple-suture line rarely occur, and percutaneous biopsy should be considered under these circumstances to avoid the unnecessary operation.