Applicability of Bosniak 2019 for renal mass classification on portal venous phase at the era of spectral CT imaging using rapid kV-switching dual-energy CT.

OBJECTIVES: To evaluate the applicability of Bosniak 2019 criteria on a monophasic portal venous phase using rapid kilovoltage-switching DECT (rsDECT). MATERIALS AND METHODS: One hundred twenty-seven renal masses assessed on rsDECT were included, classified according to Bosniak 2019 classification using MRI as the reference standard. Using the portal venous phase, virtual monochromatic images at 40, 50, and 77 keV; virtual unenhanced (VUE) images; and iodine map images were reconstructed. Changes in attenuation values between VUE and 40 keV, 50 keV, and 77 keV measurements were computed and respectively defined as ∆HU40keV, ∆HU50keV, and ∆HU77keV. The values of ∆HU40keV, ∆HU50keV, and ∆HU77keV thresholds providing the optimal diagnostic performance for the detection of internal enhancement were determined using Youden index. RESULTS: Population study included 25 solid renal masses (25/127, 20%) and 102 cystic renal masses (102/127, 80%). To differentiate solid to cystic masses, the specificity of the predefined 20 HU threshold reached 88% (95%CI: 82, 93) using ∆HU77keV and 21% (95%CI: 15, 28) using ∆HU40keV. The estimated optimal threshold of attenuation change was 19 HU on ∆HU77keV, 69 HU on ∆HU50eV, and 111 HU on ∆HU40eV. The rsDECT classification was highly similar to that of MRI for solid renal masses (23/25, 92%) and for Bosniak 1 masses (62/66, 94%). However, 2 hyperattenuating Bosniak 2 renal masses (2/26, 8%) were classified as solid renal masses on rsDECT. CONCLUSION: DECT is a promising tool for Bosniak classification particularly to differentiate solid from Bosniak I-II cyst. However, known enhancement thresholds must be adapted especially to the energy level of virtual monochromatic reconstructions. CLINICAL STATEMENT: DECT is a promising tool for Bosniak classification; however, known enhancement thresholds must be adapted according to the types of reconstructions used and especially to the energy level of virtual monochromatic reconstructions. KEY POINTS: • To differentiate solid to cystic renal masses, predefined 20 HU threshold had a poor specificity using 40 keV virtual monochromatic images. • Most of Bosniak 1 masses according to MRI were also classified as Bosniak 1 on rapid kV-switching dual-energy CT (rsDECT). • Bosniak 2 hyperattenuating renal cysts mimicked solid lesion on rsDECT.

Impact of spiking neurons leakages and network recurrences on event-based spatio-temporal pattern recognition.

Spiking neural networks coupled with neuromorphic hardware and event-based sensors are getting increased interest for low-latency and low-power inference at the edge. However, multiple spiking neuron models have been proposed in the literature with different levels of biological plausibility and different computational features and complexities. Consequently, there is a need to define the right level of abstraction from biology in order to get the best performance in accurate, efficient and fast inference in neuromorphic hardware. In this context, we explore the impact of synaptic and membrane leakages in spiking neurons. We confront three neural models with different computational complexities using feedforward and recurrent topologies for event-based visual and auditory pattern recognition. Our results showed that, in terms of accuracy, leakages are important when there are both temporal information in the data and explicit recurrence in the network. Additionally, leakages do not necessarily increase the sparsity of spikes flowing in the network. We also investigated the impact of heterogeneity in the time constant of leakages. The results showed a slight improvement in accuracy when using data with a rich temporal structure, thereby validating similar findings obtained in previous studies. These results advance our understanding of the computational role of the neural leakages and network recurrences, and provide valuable insights for the design of compact and energy-efficient neuromorphic hardware for embedded systems.

Integration of MRI to clinical nomogram for predicting pathological stage before radical prostatectomy.

BACKGROUND: Debate persists regarding whether MRI should be used routinely for preoperative evaluation of prostate cancer. OBJECTIVE: The aim is to assess the role of prostatic magnetic resonance imaging (MRI) and other preoperative data in extra-prostatic extension (EPE) evaluation. PATIENTS AND METHODS: From 2000 to 2013, 1743 patients operated for radical prostatectomy had a preoperative MRI. Age, clinical stage with digital rectal exam (DRE), PSA, prostate weight, biopsy, MRI and pathological findings of the surgical specimen were noticed. A multiparametric score of the variables independently associated with EPE was built with or without MRI on a random sample test population and internally validated. RESULTS: With mean age of 62.9 years and mean PSA of 9.6 ng/ml, the population was distributed as follows: 1424 DRE T1, 254 T2, 32 T3; on biopsy 990 Gleason score = 6 and 717 ≥ 7; on MRI 1322 iT2, 290 iT3A and 131 iT3B; on prostatectomy 15 pT0, 998 pT2, 548 pT3A, 181 pT3B and 1 pT4A. In multivariate analysis, DRE, PSA, Gleason score, prostate weight and MRI were independently associated with EPE and integrated in a score with an area under curve (AUC) of 0.74 [95% CI 0.71-0.77] (0.72 without MRI, p < 0.01) a positive predictive value of 61% and a negative predictive value of 74%, internally validated. The Hosmer-Lemeshow goodness-of-fit test showed good accuracy (p = 0.77). CONCLUSIONS: Integration of MRI with clinical data for predicting pathological stage before radical prostatectomy permits to exclude accurately EPE in 74% of cases.

Automatic three-dimensional detection of prostatic arteries using cone-beam CT during prostatic arterial embolization.

The purpose of this study was to evaluate the automatic three-dimensional detection of prostatic arteries (PAs) with the use of dual-phase cone-beam computed tomography (CT) imaging and vessel-tracking software during prostatic artery (PA) embolization (PAE). In six patients, six right PAs and five left PAs were detected by using the software (sensitivity, 92%). The false-positive arteries (right side, 14%; left side, 25%) were deleted after cone-beam CT review. Automatic software detection of PAs from cone-beam CT may permit identification of the PA during PAE.

Magnetic resonance imaging does not improve the prediction of misclassification of prostate cancer patients eligible for active surveillance when the most stringent selection criteria are based on the saturation biopsy scheme.

UNLABELLED: Study Type - Diagnostic (case series). LEVEL OF EVIDENCE: 4. OBJECTIVE: • To investigate the role of magnetic resonance imaging (MRI) in selecting patients for active surveillance (AS). PATIENTS AND METHODS: • We identified prostate cancers patients who had undergone a 21-core biopsy scheme and fulfilled the criteria as follows: prostate-specific antigen (PSA) level ≤ 10 ng/mL, T1-T2a disease, a Gleason score ≤ 6, <3 positive cores and tumour length per core <3 mm. • We included 96 patients who underwent a radical prostatectomy (RP) and a prostate MRI before surgery. • The main end point of the study was the unfavourable disease features at RP, with or without the use of MRI as AS inclusion criterion. RESULTS: • Mean age and mean PSA were 62.4 years and 6.1 ng/mL, respectively. Prostate cancer was staged pT3 in 17.7% of cases. • The rate of unfavourable disease (pT3-4 and/or Gleason score ≥ 4 + 3) was 24.0%. A T3 disease on MRI was noted in 28 men (29.2%). MRI was not a significant predictor of pT3 disease in RP specimens (P = 0.980), rate of unfavourable disease (P = 0.604), positive surgical margins (P = 0.750) or Gleason upgrading (P = 0.314). • In a logistic regression model, no preoperative parameter was an independent predictor of unfavourable disease in the RP specimen. • After a mean follow-up of 29 months, the recurrence-free survival (RFS) was statistically equivalent between men with T3 on MRI and those with T1-T2 disease (P = 0.853). CONCLUSION: • The results of the present study emphasize that, when the selection of patients for AS is based on an extended 21-core biopsy scheme, and uses the most stringent inclusion criteria, MRI does not improve the prediction of high-risk and/or non organ-confined disease in a RP specimen.

Simultaneous bilateral breast and high-resolution axillary MRI of patients with breast cancer: preliminary results.

OBJECTIVE: The aims of this study were to develop a standardized one-step procedure for simultaneous high-resolution MRI of the axilla and bilateral breast MRI and to identify nodal features suggestive of metastatic involvement. SUBJECTS AND METHODS. We studied 16 women undergoing axillary lymph node dissection after combined bilateral breast MRI and high-resolution MRI of the axilla with a maximum in-plane resolution of 0.6 x 0.4 mm. MRI was performed using a standard double breast coil and a 15-cm round flexible surface coil adapted to the axilla. High-resolution axillary sequences, including inversion recovery T2- and spin-echo T1-weighted sequences, were performed before and after gadolinium chelates bolus injection. Axillary image analysis focused on nodal morphology including size, contour regularity, cortex and hilar appearance, signal intensity, and enhancement parameters. Axillary MRI findings were compared with the final pathogic results from axillary lymph node dissection in all patients. Patients were divided into groups according to the final pathologic axillary status. Differences in MRI lymph node features across the groups were tested using a t test for quantitative data and the chisquare test or Fisher's exact test for binary data. RESULTS: The features of the axilla on high-resolution MRI that best discriminated between patients with positive pathologic findings and those with negative pathologic findings were the presence of nodes with irregular contours (p < 10(-4)), high signal intensity on T2 sequences (p < 10(-3)), marked gadolinium enhancement (p < 10(-3)), and round hila and abnormal cortexes (p < 0.05). CONCLUSION: Breast tissue and axillary lymph nodes both can be analyzed on MRI in a one-step process using a bilateral breast coil combined with a surface coil. Morphologic features observed on high-resolution MRI of the axilla can improve the identification of metastatic nodes.

Bone marrow with diffuse tumor infiltration in patients with lymphoproliferative diseases: dynamic gadolinium-enhanced MR imaging.

PURPOSE: To evaluate gadolinium enhancement of bone marrow in patients with lymphoproliferative diseases and diffuse bone marrow involvement. MATERIALS AND METHODS: Dynamic contrast material-enhanced magnetic resonance (MR) imaging of the thoracolumbar spine was performed in 42 patients with histologically proved diffuse bone marrow involvement and newly diagnosed myeloma (n = 31), non-Hodgkin lymphoma (n = 8), or Hodgkin disease (n = 3). The maximum percentage of enhancement (Emax), enhancement slope, and enhancement washout were determined from enhancement time curves (ETCs). A three-grade system for scoring bone marrow involvement was based on the percentage of neoplastic cells in bone marrow samples. Quantitative ETC values for the 42 patients were compared with ETC values for healthy subjects and with grades of bone marrow involvement by using mean t test comparisons. Receiver operating characteristic (ROC) analysis was conducted by comparing Emax values between patients with and those without bone marrow involvement. Baseline and follow-up MR imaging findings were compared in nine patients. RESULTS: Significant differences in Emax (P <.001), slope (P <.001), and washout (P =.005) were found between subjects with normal bone marrow and patients with diffuse bone marrow involvement. ROC analysis results showed Emax values to have a diagnostic accuracy of 99%. Emax, slope, and washout values increased with increasing bone marrow involvement grade. The mean Emax increased from 339% to 737%. Contrast enhancement decreased after treatment in all six patients who responded to treatment but not in two of three patients who did not respond to treatment. CONCLUSION: Dynamic contrast-enhanced MR images can demonstrate increased bone marrow enhancement in patients with lymphoproliferative diseases and marrow involvement.