Two-centre comparative experimental study of biparametric MRI at 3.0 T with and without endorectal coil using kiwifruit (Actinidia deliciosa) as a phantom for human prostate.

BACKGROUND: Application of an endorectal coil (ERC) for 3.0-T prostate magnetic resonance imaging (MRI) is contentious. We hypothesised that a multicoil phased-array protocol provides T2-weighted images (T2WI) and diffusion-weighted images (DWI) with reduced field-of-view (DWIreduced) and monoexponential apparent diffusion coefficient (ADC) maps that are technically equivalent with ERC or without ERC (noERC). METHODS: Axial T2WI (repetition time [TR] 7500 ms, echo time [TE] 98-101 ms) and DWIreduced (field-of-view 149-179 × 71-73 mm2, TR/TE 4500-5500/61-74 ms, b values, 50/800 s/mm2) ERC and noERC images were obtained on identical clinical 3.0-T scanners at two centres and compared for signal-to-noise ratio (SNR) in anterior and posterior outer pericarp (OP) and peripheral placenta (PP) in five green Hayward kiwifruit (Actinidia deliciosa, European Union regulation 543/2011 class 2). Corroboration in 21 patients with benign prostate hyperplasia (negative biopsy, prostate imaging reporting and data system version 2 ≤ 2) involved identical MRI protocols: 10 at site 1, noERC, and 11 at site 2, with ERC. Two-tailed Student's t test was used. RESULTS: With few exceptions, signal-to-noise ratio (SNR) was similar in kiwifruits and prostates for ERC and noERC. In T2WI, SNR was higher posteriorly in noERC MRI for peripheral zone (PZ) (p < 0.001). In DWIreduced, SNR was higher posteriorly in ERC-OP (p = 0.013) and ERC-PZ (p = 0.026) for b = 50 s/mm2; noERC-OP (p = 0.044) and ERC-PZ (p = 0.001) for b = 800 s/mm2; and ERC-OP (p = 0.001), noERC-OP (p = 0.001), and ERC-PZ (p = 0.001) for ADC, respectively. Volumes of kiwifruits and prostates were similar (89.2 ± 11.2 versus 90.8 ± 48.5 cm3, p = 0.638-0.920). CONCLUSIONS: Findings imply that multicoil phased-array 3.0-T prostate MRI with T2WI and DWIreduced with ADC maps provides equivalent results with and without ERC.

Everyman's prostate phantom: kiwi-fruit substitute for human prostates at magnetic resonance imaging, diffusion-weighted imaging and magnetic resonance spectroscopy.

OBJECTIVES: To apply an easy-to-assemble phantom substitute for human prostates in T2-weighted magnetic resonance imaging (T2WI), diffusion-weighted imaging (DWI) and 3D magnetic resonance spectroscopy (MRS). METHODS: Kiwi fruit were fixed with gel hot and cold compress packs on two plastic nursery pots, separated by a plastic plate, and submerged in tap water inside a 1-L open-spout plastic watering can for T2WI (TR/TE 7500/101 ms), DWI (5500/61 ms, ADC b50-800 s/mm2 map) and MRS (940/145 ms) at 3.0 T, with phased array surface coils. One green kiwi fruit was additionally examined with an endorectal coil. Retrospective comparison with benign peripheral zone (PZ) and transitional zone (TZ) of prostate (n = 5), Gleason 6-7a prostate cancer (n = 8) and Gleason 7b-9 prostate cancer (n = 7) validated the phantom. RESULTS: Mean contrast between central placenta (CP) and outer pericarp (OP, 0.346-0.349) or peripheral placenta (PP, 0.364-0.393) of kiwi fruit was similar to Gleason 7b-9 prostate cancer and PZ (0.308) in T2WI. ADC values of OP and PP (1.27 ± 0.07-1.37 ± 0.08 mm2/s × 10-3) resembled PZ and TZ (1.39 ± 0.17-1.60 ± 0.24 mm2/s × 10-3), while CP (0.91 ± 0.14-0.99 ± 0.10 mm2/s × 10-3) resembled Gleason 7b-9 prostate cancer (1.00 ± 0.25 mm2/s × 10-3). MR spectra showed peaks of citrate and myo-inositol in kiwi fruit, and citrate and "choline+creatine" in prostates. The phantom worked with an endorectal coil, too. CONCLUSIONS: The kiwi fruit phantom reproducibly showed zones similar to PZ, TZ and cancer in human prostates in T2WI and DWI and two metabolite peaks in MRS and appears suitable to compare different MR protocols, coil systems and scanners. KEY POINTS: • Kiwi fruit appear suitable as phantoms for human prostate in MR examinations. • Kiwi fruit show zonal anatomy like human prostates in T2-weighted MRI and DWI. • MR spectroscopy reliably shows peaks in kiwi fruit (citrate/inositol) and human prostates (citrate/choline+creatine). • The kiwi fruit phantom works both with and without an endorectal coil. • EU regulation No. 543/2011 specifies physical and biochemical properties of kiwi fruit.

Delineation of upper urinary tract segments at MDCT urography in patients with extra-urinary mass lesions: retrospective comparison of standard and low-dose protocols for the excretory phase of imaging.

PURPOSE: Excretory-phase CT urography (CTU) may replace excretory urography in patients without urinary tumors. However, radiation exposure is a concern. We retrospectively compared upper urinary tract (UUT) delineation in low-dose and standard CTU. MATERIAL AND METHODS: CTU (1-2 phases, 120 KV, 4 × 2.5 mm, pitch 0.875, i.v. non-ionic contrast media, iodine 36 g) was obtained with standard (14 patients, n = 27 UUTs, average 175.6 mAs/slice, average delay 16.8 min) or low-dose (26 patients, n = 86 UUTs, 29 mAs/slice, average delay 19.6 min) protocols. UUT was segmented into intrarenal collecting system (IRCS), upper, middle, and lower ureter (UU,MU,LU). Two independent readers (R1,R2) graded UUT segments as 1-not delineated, 2-partially delineated, 3-completely delineated (noisy margins), 4-completely delineated (clear margins). Chi-square statistics were calculated for partial versus complete delineation and complete delineation (clear margins), respectively. RESULTS: Complete delineation of UUT was similar in standard and low-dose CTU (R1, p > 0.15; R2, p > 0.2). IRCS, UU, and MU clearly delineated similarly often in standard and low-dose CTU (R1, p > 0.25; R2, p > 0.1). LU clearly delineated more often in standard protocols (R1, 18/6 standard, 38/31 low-dose, p > 0.1; R2 18/6 standard, 21/48 low-dose, p < 0.05). CONCLUSIONS: Low-dose CTU sufficiently delineated course of UUT and may locate obstruction/dilation, but appears unlikely to find intraluminal LU lesions.

Imaging of advanced renal cell carcinoma.

OBJECTIVES: To describe current radiological cross-sectional imaging in the detection and staging of advanced renal cell carcinoma (RCC), defined here as RCC reaching beyond the renal capsule, whether by immediate extension or by metastasis. METHODS: Review and summary of current radiological and urological literature, including original articles and reviews, retrieved from the medical data base "PubMed". RESULTS: Multi-detector-row computed tomography (MDCT) shows a sensitivity of up to 100% and specificity of about 90% for retroperitoneal disease, venous tumour thrombus, and metastasis, but limited accuracy for lymphadenopathy in RCC. Magnetic resonance imaging (MRI) is applied as a problem-solving modality, with particular strength in imaging metastasis to brain and bone. However, dynamic, contrast-enhanced- (DCE-) and arterial-spin-labelling (ASL-) MRI may help to monitor early response to angiogenesis inhibitor drugs. Ultrasonography (US) shows limited capability of identifying retroperitoneal disease, venous tumour thrombus extension, and metastasis. Positron Emission Tomography with 18-fluoro-desoxy-glucose (FDG-PET) demonstrates modest accuracy for metastasis of RCC, with positive studies being suspicious, while negative studies cannot reliably exclude disease. CONCLUSIONS: MDCT represents the diagnostic mainstay for the detection and staging of RCC. In the wake of new systemic therapies for advanced RCC, including angiogenesis inhibitor drugs, monitoring treatment response may become a new task for cross-sectional imaging.

Multidetector-row computed tomography (MDCT) in patients with a history of previous urothelial cancer or painless macroscopic haematuria.

The sensitivity and specificity of MDCT for depiction and localization of urothelial carcinoma (UC) was determined retrospectively. Axial and coronal four-row MDCT of the urinary tract (unenhanced, contrast-enhanced nephrographic, CT urography) was independently reviewed for UC by a radiologist (R1) and a urologist (R2), without other patient information, in 27 patients (22 male, five female; age, 72 +/- 11 years) with previous UC and/or painless macroscopic haematuria. Urinary tract segments included bladder, right and left upper, middle, and lower caliceal groups, renal pelvis, uretero-pelvic junction, upper, middle, and lower ureter. MDCT findings were corroborated by surgery, other invasive procedures, and 1-year follow-up, including MDCT, intravenous urography, and cystoscopy. Receiver-operating characteristic analysis was undertaken and the the area under the curve (AUC) calculated. Eighteen of 27 patients had evidence of UC (pTa, n = 3; pT1-pT3, n = 15; TNM 2002). Tumor was correctly located by both R1 and R2 in 17 patients (sensitivity, 94%; 95% confidence interval, 84-100%) and ruled out in seven (specificity, 78%; 95% confidence interval, 51-100%), with complete agreement. Each detected ten of 11 upper urinary tracts affected by UC. For 35 urinary tract segments with UC and 308 without, the AUC was 0.910 +/- 0.035 (R1) and 0.74 +/- 0.055 (R2), z = 2.4772, Bonferroni-corrected P = 0.022. MDCT depicts urinary tracts affected by UC with high sensitivity and substantial agreement between readers with different training.

Staging of renal cell carcinoma.

As in other malignant tumors, prognosis in renal cell carcinoma (RCC) depends on tumor extent and metastasis at the time of primary diagnosis. Staging systems formalize the way in which the extent of RCC is being described and classified. Primary staging of RCC aims at evaluating surgical options. Since surgical excision, which is the mainstay of therapy in non-metastatic RCC, and, recently, minimally invasive ablation methods have evolved significantly over the last decades, staging systems continue to evolve along the way. The 40-year-old Robson classification has been replaced with the TNM classification of RCC, because the latter adapts more easily to changing patterns of diagnosis and therapy. Modern cross-sectional imaging methods, such as multidetector-row computed tomography (MDCT), and magnetic resonance imaging (MRI), perform highly in T-staging of local tumor extent and M-staging of distant metastasis. However, both MDCT and MRI perform poorly in N-staging of lymphadenopathy. At present, 18-F-desoxy-glucose positron emission tomography (FDG-PET) appears to be unreliable in the detection of RCC and its metastasis. This overview of current radiological and surgical literature attempts to describe how modern staging systems for RCC are organized, and which radiological and surgical developments currently influence the way in which primary staging and prognosis of RCC depend on one another.

Catheter-based intraluminal optical coherence tomography (OCT) of the ureter: ex-vivo correlation with histology in porcine specimens.

Intraluminal optical coherence tomography (OCT) applies coherent light to provide cross-sectional images with a spatial resolution of 10-25 microm. We compared OCT and matching whole-mount histology microscopy sections of porcine upper ureters ex vivo for visualization and delineation of different tissue layers of the ureteral wall. Porcine ureters (six specimens, 24 quadrants) were flushed with normal saline solution prior to insertion of the OCT catheter (diameter, 0.014 inch, OCT wavelength, 1,300+/-20 nm). Cross-sectional OCT images were obtained in marked locations before specimens were fixed in 4% formalin, cut at marked locations, whole-mounted, and stained with hematoxilin and eosin. Visualization and delineation of different tissue layers of the ureteral wall by OCT was compared with matching histology by two independent observers (O1,O2). OCT distinguished tissue layers of the ureteral wall in all quadrants. In OCT images, O1/O2 delineated urothelium and lamina propria in 23/24 quadrants, lamina propria and muscle layer in 19/16 quadrants, inner and outer muscle layer in 13/0 quadrants, and urothelial cell layers in 13/2 quadrants, respectively. Intraluminal OCT provides histology-like images of the ureter in porcine specimens ex vivo and reliably distinguishes between urothelium and deeper tissue layers of the ureteral wall.

Likelihood of prostate cancer based on prostate-specific antigen density by MRI: retrospective analysis.

OBJECTIVE: As a screening test for prostate cancer (PCA), prostate-specific antigen (PSA) may induce unnecessary prostate biopsy in patients with PSA 4.1-10.0 ng/ml. PCA detection may be delayed in patients with PSA < or =4.0 ng/ml. MRI-based PSA density of the prostate (PSAD) and of the prostatic transitional zone (PSAT) could improve differentiation of PCA and benign prostatic hyperplasia. MATERIAL AND METHODS: Total prostate and transitional zone volumes were planimetrically determined in axial, T2-weighted fast spin echo MR images of the prostate. Serum PSA concentration was measured with an automated standardized microparticle enzyme immune assay. PSAD and PSAT were calculated in 17 patients with clinically significant PCA and 42 patients with benign prostatic hypertrophy (BPH) (66 +/- 6 versus 64 +/- 8 years, p = 0.2410, t test) who had PSA levels < or =10.0 ng/ml. RESULTS: For differentiation of BPH and PCA, PSA alone above the optimal cutoff level of 4.2 ng/ml showed an odds ratio for PCA of 6.7 (95% confidence interval [CI], 1.9-23.2). PSAD showed an odds ratio for PCA of 71.3 (95% CI, 11.8-430.9) above the optimal cutoff level of 0.07 ng/ml/cc. PSAT demonstrated an odds ratio for PCA of 320.0 (95% CI, 27.1-3781.4) above the optimal cutoff level of 0.15 ng/ml/cc. CONCLUSIONS: In patients with PSA < or =10.0 ng/ml, MRI-based PSAD and PSAT appear to improve differentiation of prostate cancer and BPH and are feasible to reduce the frequency of unnecessary prostate biopsy.