Diagnostic Performance and Interobserver Agreement of Diuretic 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Diagnosis of Upper Urinary Tract Cancer

BACKGROUND

Previous reports attempted to evaluate bladder cancer using 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) by washing out the excreted FDG with a diuretic. The purpose of this study was to evaluate the value of diuretic FDG PET/plain CT (drtPET/CT) and diuretic FDG PET/contrast-enhanced CT (drtPET/ceCT) in the assessment of upper urinary tract cancers.

MATERIALS AND METHODS

A total of 66 patients underwent drtPET/CT for suspected upper urinary tract cancer (UUTC). The study targeted 29 patients who were strongly suspected of having UUTC and underwent magnetic resonance imaging (MRI) of the upper urinary tract. A total of 29 (24 male, five female) patients, with a mean ± SD age of 73 ± 3 (range, 43-84) years, had a suspected neoplasm in the upper urinary tract. They underwent FDG PET/plain and contrast-enhanced CT before and after a diuretic and MRI including diffusion-weighted imaging (DWI). A urologist and a physician board-certified in nuclear medicine and radiology independently interpreted the standard PET/CT (stdPET/CT), drtPET/CT, drtPET/ceCT, ceCT, and MRI with DWI images. Interobserver agreement and the diagnostic performance of each modality were evaluated.

RESULTS

The kappa values of stdPET/CT, drtPET/CT, drtPET/ceCT, ceCT, and MRI were 0.381, 0.567, 0.7031, 0.448, and 0.185, respectively, with drtPET/ceCT showing the highest kappa value and the only one with good interobserver agreement (>60%). The area under the curve of drtPET/ceCT was 0.92, which was significantly higher than those of stdPET/CT (P=0.027) and MRI (P=0.047).

CONCLUSIONS

In the present study, drtPET/ceCT had the best diagnostic performance and the highest interobserver agreement for detecting upper urinary tract urothelial cancers.

Potential of Perfusion Magnetic Resonance Imaging to Predict Residual Renal Function after Radical Nephroureterectomy

INTRODUCTION

The diffusion-weighted imaging (DWI) technique with intravoxel incoherent motion model enables the estimation of capillary blood volume as a perfusion-related parameter- (PP-) value. Therefore, the PP-value of the kidney theoretically reflects renal capillary blood volume. We analyzed the usefulness of the PP-value in estimating postoperative renal function in upper-tract urothelial carcinoma (UTUC) patients.

METHODS

Forty-eight consecutive patients who underwent magnetic resonance imaging before radical nephroureterectomy from 2011 to 2018 were analyzed. A PP-map displaying PP-values on a pixel-by-pixel basis was created from DWI signals (b-values of 0, 500, and 1,000 s/mm2). Two readers independently analyzed the renal PP-value. DWI-based split renal function (SRF) of the intact kidney was calculated by splitting serum Cr-based preoperative estimated glomerular filtration rates (eGFRs). The predictive accuracy of the method was evaluated using renography as the reference standard.

RESULTS

Interobserver analysis revealed an excellent correlation value of 0.97. The SRF value showed a good linear correlation with the observed postoperative eGFR (r = 0.76, p < 0.001). The predictive accuracy of the DWI-based method was similar to that of the nuclear-based method.

CONCLUSION

This DWI-based evaluation of capillary blood volume provides a noninvasive tool for predicting the postoperative renal function, thereby facilitating the management of UTUC patients.

Oncological and renal outcomes of segmental ureterectomy vs. radical nephroureterectomy for upper tract urothelial carcinoma

Segmental ureterectomy (SU) represents a promising alternative for the treatment of upper tract urothelial carcinomas (UTUCs) as it is a less invasive procedure and guarantees the preservation of renal units. The present study evaluated oncological outcomes and renal functions following SU when compared with radical nephroureterectomy (RNU). A total of 26 patients with UTUCs who underwent SU (n=12) or RNU (n=14) were retrospectively evaluated. SU was performed in patients with clinically unifocal disease. In the SU group, the following surgeries were carried out: 7 direct ureterocystoneostomy, 1 reimplantation on psoas hitch bladder, 1 reimplantation on Boari flap bladder, 2 ureteral end-to-end anastomosis and 1 subtotal ureterectomy. In the SU group, tumors were low grade urothelial carcinoma (UC) in 6 patients, high grade UC in 5 patients and high grade UC with squamous cell differentiation in 1 patient, as well as ≤pT1 in 5, ≥pT2 in 6 and pTis in 1 patient; 'p' refers to the pathological state. The 5-year overall, cancer-specific, recurrence free and metastasis free survival in the SU group were 77.8, 87.5, 34.4 and 80.8%, respectively, which all exhibited no significant differences when compared with those of the RNU group. With regard to renal function, postoperative estimated glomerular filtration rates were preserved in the SU group. The present study demonstrated that SU does not result in poorer cancer control when compared with RNU. Thus, SU is an acceptable alternative to RNU in selected cases, as it is less invasive and preserves renal functions.

The value of adding diffusion-weighted images for tumor detection and preoperative staging in renal pelvic carcinoma for the reader's experience

PURPOSE

This retrospective study aimed to assess the value of adding diffusion-weighted magnetic resonance imaging (DWI) or gadolinium-enhanced fat-suppressed T1WI (CEI) to T2-weighted imaging (T2WI) for preoperative T categorization in renal pelvic carcinoma by the reader's experience using surgical specimens as the reference standard.

METHODS

Two radiologists (Reader 1; 3 years, 2; 13 years) reviewed 49 cases with urothelial carcinoma who underwent magnetic resonance imaging examination before surgery, independently, using three image sets: T2WI alone, T2WI plus DWI, and T2WI plus CEI for tumor detection and T categorization. The differences in the apparent diffusion coefficient values between tumors and renal parenchyma, histopathologic grade were analyzed.

RESULTS

T2WI plus CEI or DWI had high detection rates (93.4%) compared to T2WI alone. When discriminating T3a/T3b, for Reader 1, the use of T2WI plus DWI (88.0%) and T2WI plus CEI (92.0%) was significantly more accurate than T2WI alone (73%), with AUCs of 0.86, 0.86 and 0.77, respectively. For Reader 2, the accuracies were high on all image sets, with AUCs of 0.87-0.95, and the mean ADC of the tumors was significantly lower than that of the normal renal parenchyma. In addition, the mean ADC values of high-grade tumors were significantly lower than that of low-grade tumors.

CONCLUSIONS

DWI and CEI could be more helpful than T2WI alone for preoperative T categorization by less-experienced reader and DWI could be used for preoperative T categorization and for predicting the histopathologic grade of renal pelvic carcinoma.

Adrenocortical neoplasms in adulthood and childhood: distinct presentation. Review of the clinical, pathological and imaging characteristics

Adrenocortical tumors (ACT) in adulthood and childhood vary in clinical, histopathological, molecular, prognostic, and imaging aspects. ACT are relatively common in adults, as adenomas are often found incidentally on imaging. ACT are rare in children, though they have a significantly higher prevalence in the south and southeast regions of Brazil. In clinical manifestation, adults with ACT present more frequently with glucocorticoid overproduction (Cushing syndrome), mineralocorticoid syndromes (Conn syndrome), or the excess of androgens in women. Subclinical tumors are frequently diagnosed late, associated with compression symptoms of abdominal mass. In children, the usual presentation is the virilizing syndrome or virilizing association and hypercortisolism. Histopathological grading and ACT classification in malignant and benign lesions are different for adults and children. In adults, the described criteria are the Hough, Weiss, modified Weiss, and Van Slooten. These scores are not valid for children; there are other criteria, such as proposed by Wieneke and colleagues. In molecular terms, there is also a difference related to genetic alterations found in these two populations. This review discusses the imaging findings of ACT, aiming to characterize the present differences between ACT found in adults and children. We listed several differences between magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography-computed (PET-CT) and also performed a literature review, which focuses on studied age groups of published articles in the last 10 years regarding cortical neoplasm and imaging techniques. Published studies on ACT imaging in children are rare. It is important to stress that the majority of publications related to the differentiation of malignant and benign tumors are based almost exclusively on studies in adults. A minority of articles, however, studied adults and children together, which may not be appropriate.

DWI in the Etiologic Diagnosis of Excretory Upper Urinary Tract Lesions: Can It Help in Differentiating Benign From Malignant Tumors? A Retrospective Study of 98 Patients

OBJECTIVE

The objective of this study was to evaluate the diagnostic performance of high-field DWI in distinguishing benign from malignant lesions of the upper urinary tract (UUT).

MATERIALS AND METHODS

Ninety-eight patients who underwent 3-T DWI (b = 1000 s/mm(2)) for assessment of a UUT lesion were retrospectively included in the study. Data on the size, location, and mean apparent diffusion coefficient (ADC) value of the lesions were collected and correlated with the final diagnosis. ROC curve analysis was used to determine the best threshold value of the mean ADC for characterization of the lesions.

RESULTS

A total of 66 carcinomas and 33 benign lesions were identified. The mean (± SD) ADC value was statistically significantly lower for the malignant lesions than for the benign lesions (0.984 ± 0.048 vs 1.536 ± 0.067 × 10(-3) mm(2)/s; p = 0.000007). For characterization of malignant lesions, the best cutoff ADC value on the ROC curve was found to be less than or equal to 0.996 10(-3) mm(2)/s. On the basis of this value, the sensitivity and specificity of 3-T DWI for the identification of malignant UUT lesions were 78.3% and 95.5%, respectively, with a positive predictive value of 94.7% and a negative predictive value of 80.8% (p = 0.0001). The thickness of the smallest lesion was 3 mm. The mean ADC value of high-grade tumors was not statistically significantly lower than that of low-grade tumors. The best cutoff value for predicting benignancy was greater than or equal to 1.100 × 10(-3) mm(2)/s with sensitivity of 90.9%, specificity of 82.6%, positive predictive value of 83.3%, and negative predictive value of 90.5%.

CONCLUSION

The ADC measurement is a useful additional parameter in the differentiation of benign from malignant UUT lesions.

Imaging of upper urinary tract cancer: using conventional MRI and diffusion-weighted MRI with different b values

BACKGROUND

Diffusion-weighted magnetic resonance imaging (DW-MRI) has been considered to be useful in diagnosing upper urinary tract (UUT) disease; however, the value of DW-MRI with different b values has not been reported.

PURPOSE

To evaluate the performance of using conventional MRI alone and in combination with DWI with different b values in diagnosing UUT cancer.

MATERIAL AND METHODS

Seventy patients with suspected UUT cancer underwent conventional MRI (T1-weighted and T2-weighted) and DW-MRI (b = 500 and 1500 s/mm(2)) on a 3 T-MRI scanner. The ureteroscopic and histopathologic findings were compared with the imaging findings. The utility of detecting UUT cancer using conventional MRI (set A), combined DW-MRI (b = 500 s/mm(2)) and conventional MRI (set B), and combined DW-MRI (b = 1500 s/mm(2)) and conventional MRI (set C) were independently evaluated by two readers.

RESULTS

A total of 32 patients had verified cancer; 23 patients had benign UUT diseases, and 15 had no abnormality. Sets B and C had significantly improved diagnostic accuracy for UUT cancer compared with set A; the specificity in diagnosing UUT cancer was significantly improved when using set C compared with sets A and B. In patients without UUT obstructions, improved sensitivity and accuracy in diagnosis was achieved when using sets B and C compared with set A.

CONCLUSION

Using DW-MRI in combination with conventional MRI provides increased diagnostic accuracy and sensitivity in patients without UUT obstruction. The combination of conventional MRI and DW-MRI with a higher b value (1500 s/mm(2)) improved the specificity in diagnosing UUT cancer compared to conventional sequences and DW-MRI with a lower b value (500 s/mm(2)).

Bone abnormal signal incidentally found in pre-biopsy diffusion-weighted MRI for suspected prostate cancer: what does it reflect?

OBJECTIVE

To clarify the clinical significance of incidentally found diffusion-weighted MRI (DW-MRI)-positive findings on pre-biopsy MRI in patients with suspected prostate cancer.

PATIENTS AND METHODS

754 consecutive patients with suspected prostate cancer underwent pelvic MRI including DW-MRI. 43 DW-MRI-positive bone lesions were found in 27 patients. Imaging findings of these lesions were compared with the clinical diagnosis.

RESULTS

Of the 43 DW-MRI-positive bone lesions, 21 (48.8%) were diagnosed as metastatic prostate cancer. The remaining 22 (51.2%) were diagnosed as red bone marrow in 17, enchondroma in 1, ganglion in 1, osteoma in 1, fibrous dysplasia in 1 and bone infarction in 1. Enchondroma, ganglion, osteoma and fibrous dysplasia all showed T1-weighted imaging (T1WI) low and T2-weighted imaging (T2WI) high signals, while others, including prostate cancer metastases, showed T1WI and T2WI low signals. Of the 40 lesions with T1WI and T2WI low signals, metastatic prostate cancer had higher apparent diffusion coefficient values (median 0.42 × 10(-3) mm(2)/s) than other lesions (0.26 × 10(-3) mm(2)/s; p < 0.0001).

CONCLUSIONS

DW-MRI-positive bone lesions represent various coexisting types of bone lesions, including metastatic cancer in patients with suspected prostate cancer. T2WI findings and apparent diffusion coefficient values can be helpful in diagnosing metastatic cancer.

Utility of MRI features in differentiation of central renal cell carcinoma and renal pelvic urothelial carcinoma

OBJECTIVE

The purpose of this article is to evaluate the utility of various morphologic and quantitative MRI features in differentiating central renal cell carcinoma (RCC) from renal pelvic urothelial carcinoma.

MATERIALS AND METHODS

Sixty patients (39 men and 21 women; mean [± SD] age, 65 ± 14 years; 48 with central RCC and 12 with renal pelvic urothelial carcinoma) who underwent MRI, including diffusion-weighted imaging (b values, 0, 400, and 800 s/mm(2)) and dynamic contrast-enhanced imaging, before histopathologic confirmation were included. Tumor T2 signal intensity and apparent diffusion coefficients (ADCs) were measured and normalized to muscle and CSF (hereafter referred to as normalized T2 signal and normalized ADC, respectively) and then were compared using receiver operating characteristic analysis. Also, two blinded radiologists independently assessed all tumors for various qualitative features, which were compared with the Fisher exact test and unpaired Student t test.

RESULTS

Urothelial carcinoma exhibited significantly lower normalized ADC than did RCC (p = 0.008), but no significant difference was seen in ADC or normalized T2 signal intensity (p = 0.247-0.773). Normalized ADC had the highest area under the curve (0.757); normalized ADC below an optimal threshold of 0.451 was associated with sensitivity of 83% and specificity of 71% for diagnosing urothelial carcinoma. Features that were significantly more prevalent in urothelial carcinoma included global impression of urothelial carcinoma, location centered within the collecting system, collecting system defect, extension to the ureteropelvic junction, preserved renal shape, absence of cystic or necrotic areas, absence of hemorrhage, homogeneous enhancement, and hypovascularity (all p < 0.033). Increased T1 signal intensity suggestive of hemorrhage was significantly more prevalent in RCC (p = 0.02). Interreader agreement for the subjective features ranged from 61.7% to 98.3%.

CONCLUSION

In addition to various qualitative MRI parameters, normalized ADC has utility in differentiating central RCC from renal pelvic urothelial carcinoma. Such differentiation may assist decisions regarding possible biopsy and treatment planning.

Apparent diffusion coefficient value reflects invasive and proliferative potential of bladder cancer

PURPOSE

To elucidate a role of apparent diffusion coefficient (ADC) value as a biomarker of bladder cancer, we investigated its associations with Ki-67 labeling index (LI) along with classical clinicopathological prognosticators.

MATERIALS AND METHODS

Diffusion-weighted MRI (DW-MRI) at 1.5 Tesla using b-values of 0, 500, 1000, and 2000 s/mm(2) was prospectively taken before transurethral resection by 132 bladder cancer patients. ADC value of index tumors was measured and compared with clinicopathological prognosticators including Ki-67 LI.

RESULTS

ADC value was significantly lower in tumors with higher Ki-67 LIs, sessile tumors (versus papillary), larger tumors, higher grade disease, and higher T stage disease. ADC value inversely correlated with Ki-67 LI (ρ = -0.57; P < 0.0001). On multiple regression analysis, T stage and Ki-67 LI significantly correlated with ADC value. The Akaike information criterion confirms these two parameters constitute the best model for determining ADC value. Similarly, T stage and ADC value significantly correlated with Ki-67 LI and these two parameters composed the best model for predicting Ki-67 LI.

CONCLUSION

ADC value would reflect T stage and Ki-67 LI, representing invasive and proliferative potential, respectively. ADC value is likely to serve as a biomarker reflecting aggressiveness of bladder cancer.

Apparent diffusion coefficient as a prognostic biomarker of upper urinary tract cancer: a preliminary report

OBJECTIVES

To investigate the role of apparent diffusion coefficient (ADC) as a biomarker reflecting the aggressiveness of upper urinary tract urothelial cell carcinoma (UUT-UCC).

METHODS

Thirty-four consecutive patients treated with nephroureterectomy for non-metastatic disease were prospectively enrolled in this study. ADC was compared with clinicopathological variables including Ki-67 labelling index (LI) and cancer-specific survival (CSS).

RESULTS

The overall 3-year CSS rate was 82 % (median follow-up, 36 months). ADC was significantly lower in grade 3 disease than in grades 1-2 disease (P = 0.011) and significantly and inversely correlated with Ki-67 LI (ρ = -0.59, P = 0.0002). Low ADCs (<1.10 × 10(-3) mm(2)/s) were significantly associated with shorter CSS (P = 0.039). Multivariate analysis of preoperative variables identified ADC and MRI-based clinical T stage as independent indicators of shorter CSS; the patients were stratified into high-risk (8 patients with low ADC and at least clinical T3) and low-risk (26 patients with high ADC or not more than clinical T2) groups with 3-year CSS rates of 43 % and 93 % (P = 0.0003).

CONCLUSIONS

Our preliminary data suggest the potential role of ADC as a quantitative biomarker reflecting the aggressiveness of UUT-UCC. ADC might be useful for preoperative risk stratification of UUT-UCC patients.

KEY POINTS

• Diffusion-weighted MRI offers new information about the aggressiveness of urinary tract cancers. • The apparent diffusion coefficient acts as a quantitative biomarker for upper urinary tract cancers. • ADC inversely correlates with immunohistochemical and histological grading of UUT-UCC. • ADC offers a prognosis for UUT-UCC patients treated with nephroureterectomy.

Selective bladder preservation with curative intent for muscle-invasive bladder cancer: a contemporary review

Radical cystectomy plus urinary diversion, the reference standard treatment for muscle-invasive bladder cancer, associates with high complication rates and compromises quality of life as a result of long-term effects on urinary, gastrointestinal and sexual function, and changes in body image. As a society ages, the number of elderly patients unfit for radical cystectomy as a result of comorbidity will increase, and thus the demand for bladder-sparing approaches for muscle-invasive bladder cancer will also inevitably increase. Trimodality bladder-sparing approaches consisting of transurethral resection, chemotherapy and radiotherapy (Σ 55-65 Gy) yield overall survival rates comparable with those of radical cystectomy series (50-70% at 5 years), while preserving the native bladder in 40-60% of muscle-invasive bladder cancer patients, contributing to an improvement in quality of life for such patients. Limitations of the trimodality therapy include (i) muscle-invasive bladder cancer recurrence in the preserved bladder, which most often arises in the original muscle-invasive bladder cancer site; (ii) potential lack of curative intervention for regional lymph nodes; and (iii) increased morbidity in the event of salvage radical cystectomy for remaining or recurrent disease as a result of high-dose pelvic irradiation. Consolidative partial cystectomy with pelvic lymph node dissection followed by induction chemoradiotherapy at lower dose (e.g. 40 Gy) is a rational strategy for overcoming such limitations by strengthening locoregional control and reducing radiation dosage. Molecular profiling of the tumor and functional imaging might play important roles in optimal patient selection for bladder preservation. Refinement of radiation techniques, intensified concurrent or adjuvant chemotherapy, and novel sensitizers, including molecular targeting agent, are also expected to improve outcomes and consequently provide more muscle-invasive bladder cancer patients with favorable quality of life.

Diagnostic performance of diffusion-weighted magnetic resonance imaging in bladder cancer: potential utility of apparent diffusion coefficient values as a biomarker to predict clinical aggressiveness

OBJECTIVES

The diagnostic performance of diffusion-weighted magnetic resonance imaging (DW-MRI) in bladder cancer and the potential role of apparent diffusion coefficient (ADC) values in predicting pathological bladder cancer phenotypes associated with clinical aggressiveness were investigated.

METHODS

One hundred and four bladder cancer patients underwent DW-MRI and T2-weighted magnetic resonance imaging (T2W-MRI) before transurethral resection. The image sets were reviewed by two independent radiologists. ADC values were measured in 121 eligible tumours.

RESULTS

In detecting patients with bladder cancer, DW-MRI exhibited high sensitivity equivalent to that of T2W-MRI (>90%). Interobserver agreement was excellent for DW-MRI (κ score, 0.88) though moderate for T2W-MRI (0.67). ADC values were significantly lower in high-grade (vs. low-grade, P < 0.0001) and high-stage (T2 vs. T1 vs. Ta, P < 0.0001) tumours. At a cut-off ADC value determined by partition analysis, clinically aggressive phenotypes including muscle-invasive bladder cancer (MIBC) and high-grade T1 disease were differentiated from less aggressive phenotypes with a sensitivity of 88%, a specificity of 85% and an accuracy of 87%.

CONCLUSION

DW-MRI exhibits high diagnostic performance in bladder cancer with excellent objectivity. The ADC value could potentially serve as a biomarker to predict clinical aggressiveness in bladder cancer.

Usefulness of diffusion-weighted MRI in diagnosis of upper urinary tract cancer

OBJECTIVE

The purpose of this study was to prospectively evaluate the diagnostic ability of diffusion-weighted MRI (DWI) for detecting upper urinary tract cancer.

SUBJECTS AND METHODS

Seventy-six patients (36 women, 40 men; median age, 70 years) suspected of having upper urinary tract cancer underwent T1- and T2-weighted imaging and DWI (b values, 0 and 800 s/mm(2)) with or without T1-weighted dynamic contrast-enhanced MRI (DCE-MRI). Two radiologists independently interpreted the images.

RESULTS

Of the 76 patients suspected of having upper urinary tract cancer, 49 were diagnosed with upper urinary tract cancer and the remaining 27 were diagnosed as not having upper urinary tract cancer. The sensitivity, specificity, and accuracy of DWI interpretation for each reviewer was 92%, 96%, and 93% and 94%, 81%, and 89%, respectively. The sensitivity and accuracy of DWI were significantly higher than those of T1- and T2-weighted imaging (p < 0.01 and p = 0.03 for reviewer 1 and p < 0.01 for both values for reviewer 2), although the specificity did not change. The diagnostic abilities of DWI and DCE-MRI were not significantly different. The interobserver agreement of DWI between the two reviewers was excellent (κ score = 0.801). The apparent diffusion coefficient values of upper urinary tract cancer with grade 3 were significantly lower than those of upper urinary tract cancer with grades 2 and 1 (p < 0.028).

CONCLUSION

DWI provides accurate information for the diagnosis of upper urinary tract cancer in a noninvasive manner. The additional use of DWI to T1- and T2-weighted imaging increases the sensitivity of MRI in identifying upper urinary tract cancer with excellent interobserver agreement. Furthermore, DWI could be a useful adjunct to preoperative assessment of histologic grade.

Diffusion-weighted imaging of the renal and adrenal lesions

OBJECTIVES

The purpose of this study was to calculate the apparent diffusion coefficient (ADC) values of different renal and adrenal lesions to evaluate the ability of diffusion-weighted imaging in characterizing masses and determining malignancy.

METHODS

A total of 52 patients consisting of 67 renal lesions and 28 patients with 33 adrenal lesions in addition to 50 healthy controls with normal kidneys were enrolled in the study. Diffusion-weighted imaging was performed with b factors of 0, 500, and 1000 s/mm2, and the ADCs of the normal kidney and renal and adrenal lesions were calculated.

RESULTS

The mean (SD) ADCs of the renal cortex and medulla of the control group were 2.08 (0.22) x 10(-3) and 1.94 (0.18) x 10(-3) mm2/s, respectively. Focal renal lesions were as follows: simple cysts (2.94 [0.20] x 10(-3) mm2/s), hemorrhagic cysts (1.71 [0.38] x 10(-3) mm2/s), angiomyolipomas (1.40 [0.21] x 10(-3) mm2/s), renal cell carcinomas (1.06 [0.39] x 10(-3) mm2/s), metastases (1.50 [0.13] x 10(-3) mm2/s), and hydronephrosis (1.54 [0.25] x 10(-3) mm2/s). The mean ADCs of all these pathologies were significantly different when compared with normal parenchyma. Diffusion-weighted imaging was also able to differentiate angiomyolipomas and hemorrhagic cysts from renal cell carcinomas. Adrenal lesions were subgrouped as adenomas (1.41 [0.27] x M10(-3) mm2/s), nonadenomatous solid masses (1.08 [0.28] x 10(-3) mm2/s), and cysts (2.82 [0.24] x 10(-3) mm2/s). The mean ADCs of adenomas were significantly different when compared with nonadenomatous solid masses and cysts.

CONCLUSIONS

Our findings show that ADC measurement has a potential ability to differentiate benign and malignant focal renal and adrenal lesions with the guidance of conventional sequences. When used alone, diffusion-weighted imaging may lead to misdiagnoses due to overlapping ADCs of the lesions.

Initial experience of diffusion-weighted magnetic resonance imaging to assess therapeutic response to induction chemoradiotherapy against muscle-invasive bladder cancer

OBJECTIVES

To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DWI) in predicting therapeutic response to low-dose chemoradiotherapy (LCRT) against muscle-invasive bladder cancer (MIBC). Accurate assessment of response to induction therapy is an essential part of bladder-sparing therapeutic protocols against MIBC. However, conventional imaging studies are not useful in evaluating therapeutic response because of their inability to distinguish residual cancer from changes secondary to the treatment.

METHODS

Twenty patients with clinical T2-4aN0M0 bladder urothelial carcinoma (T2/T3/T4a: n = 10/8/2) who underwent induction LCRT comprising external beam radiotherapy to the bladder (40 Gy) concomitant with 2 cycles of cisplatin administration (20 mg/d for 5 days) followed by partial (n = 13) or radical cystectomy (n = 7) were prospectively enrolled. The patients underwent magnetic resonance imaging examinations with T2-weighted imaging (T2W), dynamic contrast-enhanced T1-weighted imaging (DCE), and DWI after LCRT. A finding of each protocol was compared with a pathologic finding of cystectomy specimen.

RESULTS

Pathologic examination of cystectomy specimens revealed pathologic complete response in 13 (65%) of the 20 patients. The sensitivity/specificity/accuracy of T2W, DCE, and DWI in predicting pathologic response was 43/45/44%, 57/18/33%, and 57/92/80%, respectively. Despite comparable sensitivity, DWI was significantly superior in specificity and accuracy to T2W (P = .03 and .02, respectively) and DCE (P = .002 for both).

CONCLUSIONS

This is the first study to show the feasibility of DWI over T2W and DCE for assessing therapeutic response to induction chemoradiotherapy against MIBC. The high specificity of DWI indicates that DWI is useful to accurately predict pathologic complete response, allowing more optimal patient selection in bladder-sparing protocols.

Bladder cancer: diagnosis with diffusion-weighted MR imaging in patients with gross hematuria

PURPOSE

To prospectively evaluate the usefulness of diffusion-weighted (DW) magnetic resonance (MR) imaging for the detection of bladder neoplasms in patients with gross hematuria of lower urinary tract origin.

MATERIALS AND METHODS

The study protocol received institutional ethical committee approval, and informed consent was obtained. Between April 2007 and March 2008, 130 consecutive patients with gross hematuria whose upper urinary tract had a normal appearance at ultrasonographic examination were prospectively enrolled. Mean age was 59.4 years (range, 45-75 years). All patients were evaluated by using T2-weighted high-spatial-resolution MR imaging of the urinary bladder, followed by DW MR imaging. Two radiologists independently interpreted the T2-weighted and DW images, and discrepancies were resolved by consensus. Agreement was evaluated by using the kappa statistic. All patients underwent conventional cystoscopy. With cystoscopy and the final histopathologic findings as the reference standards, a comparison with imaging findings was performed by using the McNemar test.

RESULTS

The consensus diagnostic performance of DW MR imaging for identification of bladder tumors was: sensitivity, 98.1% (104 of 106); specificity, 92.3% (24 of 26); PPV, 100% (104 of 104); negative predictive value, 92.3% (24 of 26); and accuracy, 97.0% (128 of 132). Two cases were falsely negative on T2-weighted MR images but were correctly diagnosed by using DW MR images. The agreement between DW MR imaging results and cystoscopic findings was excellent (kappa = 0.94) for identification of bladder neoplasm. DW MR imaging had a sensitivity and PPV of 98.5% (128 of 130) and 100% (128 of 128), respectively, for determining the cause of hematuria.

CONCLUSION

DW MR imaging is a highly reliable imaging approach for identification of bladder tumors in patients with gross hematuria.

Bladder tumour staging: comparison of diffusion- and T2-weighted MR imaging

The aim of this work was to evaluate the clinical feasibility of diffusion-weighted (DW) MRI in detection and staging of urinary bladder tumour and to compare DW MRI with the T(2)-weighted technique. One hundred and six patients with bladder tumour were prospectively included in our study. All patients were evaluated with MR imaging. We started with axial T(2)-weighted high resolution MR of the urinary bladder, then DW MRI. Two radiologists independently interpreted the MR images, and discrepancies were resolved by consensus. The accuracy of DW MRI in staging of bladder tumour was evaluated using the final histopathological findings. In DW imaging (DWI) staging accuracy was 63.6% and 69.6% in differentiating superficial from invasive tumours and organ-confined from non-organ-confined tumours, respectively. On a stage by a stage basis, DWI accuracy was 63.6% (21/33), 75.7% (25/33), 93.7% (30/32) and 87.5% (7/8) for stages T1, T2, T3 and T4, respectively. In the T(2)-weighted technique, the overall staging accuracy was only 39.6% and accuracy for differentiating superficial from invasive tumours and organ-confined from non-organ-confined tumours was 6.1% and 15.1%, respectively. DW is superior to T(2)-weighted MRI in staging of organ-confined tumours (< or =T2) and both techniques are comparable in the evaluation of higher-stage tumours.

Diffusion-weighted MR imaging of the kidneys and the urinary tract

There is currently a growing interest in applications of diffusion-weighted imaging (DWI) in the abdomen and pelvis. DWI provides original functional information where the signal and contrast are determined by the microscopic mobility of water. DWI can provide additional information over conventional MR sequences, and could potentially be used as an alternative to contrast-enhanced sequences in patients with chronic renal insufficiency at risk of nephrogenic systemic fibrosis. We provide an overview on basic physics background on DWI applied to the kidneys, and we summarize the current available data, including our recent experience.