Nelly Tan

Clinical and Epidemiologic Characteristics Cannot Distinguish Community-Associated Methicillin-Resistant Staphylococcus aureus Infection from Methicillin-Susceptible S. aureus Infection: A Prospective Investigation

BACKGROUND Community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) infection has become common worldwide. Some researchers have argued that empirical therapy for MRSA should be given only to patients with suspected CA S. aureus infections who have risk factors for acquisition of MRSA. However, there are no prospective data examining this approach. METHODS We prospectively enrolled consecutive patients who were hospitalized with S. aureus infection, administered a detailed questionnaire, and collected clinical and microbiological information. RESULTS Of the 280 consenting patients, 180 were adults with CA S. aureus infection. Among these subjects, 108 (60%) had MRSA infection, and 78 (40%) had methicillin-susceptible S. aureus (MSSA) infection. MRSA infection was associated with younger age (P<.0001); skin/soft-tissue infection (P=.015); snorting/smoking illegal drugs (P=.01); recent incarceration (P=.03); lower comorbidity index (P=.01); more frequent visits to bars, raves, and/or clubs (P=.03); and higher frequency of laundering clothes in hot water (P=.05). However, the sensitivity, specificity, and predictive values for these factors for discriminating CA-MRSA infection from CA-MSSA infection were relatively poor. Post-hoc modeling revealed that, even in a 10% (i.e., low) MRSA prevalence population, patients lacking the 3 strongest MRSA risk factors would still have a 7% posttest probability of MRSA. Most MRSA strains belonged to the ST-8/USA300 genotype, contained SCCmec type IV, and shared virulence factors commonly found in the ST1:USA400 clone. MSSA strains were genotypically heterogeneous. CONCLUSIONS We found that clinical and epidemiological risk factors in persons hospitalized for CA S. aureus infection cannot reliably distinguish between MRSA and MSSA. Our findings have important implications for the choice of empirical antibiotic therapy for suspected S. aureus infections and for infection control.

Multifocality and Prostate Cancer Detection by Multiparametric Magnetic Resonance Imaging: Correlation with Whole-mount Histopathology

BACKGROUND Multiparametric magnetic resonance imaging (mp-MRI) is increasingly used in prostate cancer (CaP). Understanding the limitations of tumor detection, particularly in multifocal disease, is important in its clinical application. OBJECTIVE To determine predictors of CaP detection by mp-MRI as confirmed by whole-mount histopathology. DESIGN, SETTING, AND PARTICIPANTS A retrospective study was performed of 122 consecutive men who underwent mp-MRI before radical prostatectomy at a single referral academic center. A genitourinary radiologist and pathologist collectively determined concordance. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The odds of tumor detection were calculated for clinical, MRI, and histopathologic variables using a multivariate logistic regression model. RESULTS AND LIMITATIONS The 122 patients had 283 unique histologically confirmed CaP tumor foci. Gleason score was 6 in 21 (17%), 7 in 88 (72%), and ≥8 in 13 (11%) patients. Of the 122 cases, 44 (36%) had solitary and 78 (64%) had multifocal tumors. Overall mp-MRI sensitivity for tumor detection was 47% (132/283), with increased sensitivity for larger (102/141 [72%] >1.0 cm), higher-grade (96/134 [72%] Gleason ≥7) tumors, and index tumors (98/122 [80%]). Index tumor status, size, and prostate weight were significant predictors of detection in a multivariate analysis, and multifocality did not adversely impact detection of index tumors. A prostatectomy population was necessary by design, which may limit the ability to generalize these results. CONCLUSIONS Sensitivity for tumor detection increased with tumor size and grade. Index tumor status and tumor size were the strongest predictors of tumor detection, regardless of tumor focality. Some 80% of index tumors were detected, but nonindex tumor detection, even of high-grade lesions, was poor. These findings have important implications for focal therapy. PATIENT SUMMARY We evaluated the ability of magnetic resonance imaging (MRI) to detect cancer in patients undergoing prostatectomy. We found that tumor size and grade were important predictors of tumor detection, and although cancer is often multifocal, MRI is often able to detect the worst focus of cancer.

A Prospective Investigation of Outcomes after Hospital Discharge for Endemic, Community-Acquired Methicillin-Resistant and -Susceptible Staphylococcus aureus Skin Infection

BACKGROUND Although community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection has become increasingly common, prospective data on outcomes of patients with skin infection remain poorly defined. METHODS We prospectively observed a cohort of 201 patients discharged after hospitalization for CA-MRSA infection or community-acquired methicillin-susceptible S. aureus (CA-MSSA) infection. Patients were interviewed 30 and 120 days after they received a diagnosis. Our primary outcome was clinical response, defined as no relapse, new S. aureus infection, or need for antibiotics at day 30. RESULTS Among 117 patients with skin infection, the nonresponse rate at day 30 was similar among patients with CA-MRSA infection and those with CA-MSSA infection (23 [33%] of 70 vs. 13 [28%] of 47 patients; P=.55). Lack of incision and drainage was associated with nonresponse at day 30 (P=.005), but other clinical factors, including receipt of antibiotics inactive against the infecting strain, were not. Patients with CA-MSSA infection were more likely to be rehospitalized (P=.003) and to believe subjectively that they had not been cured (P=.002) at day 30. At day 30, there was a trend for close contacts of CA-MRSA-infected patients to develop a similar infection (13% vs. 4%; odds ratio, 3.3; 95% confidence interval, 0.7-15.8; P=.2). CONCLUSION Although it is believed patients with CA-MRSA skin infection may have more serious outcomes than those with CA-MSSA skin infection, we found similar outcomes in these 2 groups after hospital discharge. Clinical nonresponse at day 30 was associated with a lack of receipt of incision and drainage. Our data also suggest that close contacts of persons with CA-MRSA skin infection may have a higher likelihood of acquiring an infection.

Prostate Cancers Diagnosed at Repeat Biopsy are Smaller and Less Likely to be High Grade

PURPOSE We investigated whether prostate cancer diagnosed on initial prostate biopsy had worse pathological outcomes compared to that diagnosed on repeat prostate biopsy. MATERIALS AND METHODS We reviewed 905 newly diagnosed prostate cancer cases from 2000 to 2007. Patients were stratified by the number of previous biopsies, including the initial biopsy in 690, and 1 and 2 or greater negative previous biopsies in 142 and 73, respectively. We analyzed Gleason sum, number of cores taken, percent of positive cores and bilaterality of prostate cancer. Clinically insignificant cancers were defined according to prostate specific antigen density 0.4 ng/ml or less, 3 or fewer positive cores, 50% or less of maximum cancer in any core and Gleason sum 6 or less. RESULTS Prostate cancer was diagnosed in 57%, 23% and 21% of cases in the initial, and 1 and 2 or greater negative previous biopsies groups, respectively. Initial prostate biopsy showed a higher number and percent of positive cores, and the maximum percent of prostate cancer involved in a core. However, the Gleason pattern distribution differed significantly in the 3 groups with the highest percent (14%) of Gleason sum 8 or greater in the subset with 2 or greater negative previous biopsies (p <0.01). On multivariate analysis accounting for prostate specific antigen, digital rectal examination, age and biopsy schema the number of previous biopsies was an independent predictor of the number and percent of positive cores, maximum prostate cancer involved in a core, and bilaterality (p <0.01). Only prostate specific antigen, digital rectal examination and age but not the number of previous biopsies independently predicted Gleason sum (p <0.01). CONCLUSIONS Prostate cancer diagnosed on initial prostate biopsy had higher volume. However, there were a significant number of high grade prostate cancers detected on the third or greater prostate biopsy, underscoring the importance of repeat prostate biopsy in the setting of increased or increasing prostate specific antigen despite negative previous prostate biopsy.

Qualitative and Quantitative MDCT Features for Differentiating Clear Cell Renal Cell Carcinoma From Other Solid Renal Cortical Masses

OBJECTIVE The purpose of this study was to differentiate clear cell renal cell carcinoma (RCC) from other solid renal masses on four-phase MDCT. MATERIALS AND METHODS Our study cohort included all pathologically proven solid renal masses that underwent pretreatment four-phase MDCT at our institution from 2001 to 2012. Both retrospective qualitative analysis (blinded dual-radiologist evaluation of morphologic features: enhancement pattern, lesion contour, neovascularity, and calcification) and quantitative analysis (mean absolute and relative attenuation and changes in attenuation across phases) were performed. ANOVA with post-hoc analysis, Pearson chi-square tests, and ROC analysis were used. RESULTS One hundred fifty-six consecutive patients (99 men, 57 women) with a mean age of 62.7 years (range, 26-91 years) had 165 solid renal masses (median size, 3.0 cm): 86 clear cell RCCs, 36 papillary RCCs, 10 chromophobe RCCs, 23 oncocytomas, and 10 lipid-poor angiomyolipomas. Kappa for interradiologist agreement regarding morphologic features was 0.33-0.76. There were significant associations between histologic subtype and enhancement pattern (p < 0.001), lesion contour (p < 0.014), and neovascularity (p < 0.001). Clear cell RCC had the highest mean relative corticomedullary attenuation (p < 0.02). Clear cell RCC had greater deenhancement than oncocytoma (p < 0.001); deenhancement less than 50 HU or relative corticomedullary attenuation greater than 0% differentiated clear cell RCC from oncocytoma with a positive predictive value of 90%. Lipid-poor angiomyolipoma had the highest mean absolute unenhanced attenuation (p < 0.01); absolute unenhanced attenuation greater than 45 HU and relative corticomedullary attenuation less than 10% differentiated lipid-poor angiomyolipoma from clear cell RCC with a negative predictive value of 97%. CONCLUSION Four-phase MDCT renal attenuation profiles enable differentiation of clear cell RCC from other solid renal cortical masses, most notably papillary RCC and lipid-poor angiomyolipoma.

The Role of Magnetic Resonance Imaging in Delineating Clinically Significant Prostate Cancer

OBJECTIVE To determine whether multiparametric magnetic resonance imaging might improve the identification of patients with higher risk disease at diagnosis and thereby reduce the incidence of undergrading or understaging. METHODS We retrospectively reviewed the clinical records of 115 patients who underwent multiparametric magnetic resonance imaging before radical prostatectomy. We used Epsteins criteria of insignificant disease with and without a magnetic resonance imaging (MRI) parameter (apparent diffusion coefficient) to calculate sensitivity, specificity, as well as negative and positive predictive values [NPV and PPV] across varying definitions of clinically significant cancer based on Gleason grade and tumor volume (0.2 mL, 0.5 mL, and 1.3 mL) on whole-mount prostate specimens. Logistic regression analysis was performed to determine the incremental benefit of MRI in delineating significant cancer. RESULTS The majority had a prostate-specific antigen from 4.1-10.0 (67%), normal rectal examinations (90%), biopsy Gleason score ≤ 6 (68%), and ≤ 2 cores positive (55%). Of the 58 patients pathologically staged with Gleason 7 or pT3 disease at prostatectomy, Epsteins criteria alone missed 12 patients (sensitivity of 79% and NPV of 68%). Addition of apparent diffusion coefficient improved the sensitivity and NPV for predicting significant disease at prostatectomy to 93% and 84%, respectively. MRI improved detection of large Gleason 6 (≥ 1.3 mL, P = .006) or Gleason ≥ 7 lesions of any size (P <.001). CONCLUSION Integration of MRI with existing clinical staging criteria helps identify patients with significant cancer. Clinicians should consider utilizing MRI in the decision-making process.

Characteristics of Detected and Missed Prostate Cancer Foci on 3-T Multiparametric MRI Using an Endorectal Coil Correlated With Whole-Mount Thin-Section Histopathology

OBJECTIVE The objective of this study was to determine the characteristics of prostate cancer foci missed on 3-T multiparametric MRI performed with an endorectal coil. MATERIALS AND METHODS The MRI examinations of 122 patients who underwent 3-T multiparametric MRI of the prostate with an endorectal coil were compared with whole-mount histopathology obtained after radical prostatectomy. The mean age of the patients was 60.6 years (SD, 7.6 years), and the mean prostate-specific antigen value was 7.2 ng/mL (SD, 5.9 ng/mL). The clinical, multiparametric MRI (i.e., T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging), and histopathologic features were obtained. After an independent review, two blinded genitourinary radiologists matched each case with a genitourinary pathologist. A structured reporting system was used to classify the multiparametric MRI features of each MRI-detected lesion. A chi-square analysis was performed for categoric variables, and the t test was performed for continuous variables. RESULTS On whole-mount histopathology, 285 prostate cancer foci were detected in 122 patients. Of the 285 cancer foci detected at histopathology, 153 (53.3%) were missed on MRI and 132 (46.7%) were detected on MRI. Of the missed lesions, 75.2% were low-grade prostate cancer. Multiparametric MRI had a significantly higher sensitivity for prostate cancer foci 1 cm or larger than for subcentimeter foci (81.1% vs 18.9%, respectively; p < 0.001), for lesions with a Gleason score of 7 or greater than for lesions with a Gleason score of 6 (72.7% vs 27.3%; p < 0.01), and for index lesions than for satellite lesions (80.3% vs 20.8%; p < 0.01). The 3-T multiparametric MRI examinations showed a higher detection rate for lesions in the midgland or base of the gland compared with lesions in the apex (52.3% vs 22.0%, respectively; p < 0.01). CONCLUSION Compared with the prostate cancer lesions that were detected on multiparametric MRI, the prostate cancer lesions that were missed were significantly smaller, were more likely to be low-grade lesions (i.e., Gleason score of 6), were more commonly satellite lesions, and were more likely to be located in the prostatic apex.

Radical prostatectomy: value of prostate MRI in surgical planning

The introduction of serum prostate-specific antigen to the prostate cancer screening algorithm has led to an increase in prostate cancer diagnosis as well as a migration toward lower-stage cancer at the time of diagnosis. This stage migration has coincided with changes in treatment options; these include active surveillance, new therapies, and advances in surgical techniques. Use of robot-assisted radical prostatectomy (RARP) as a surgical technique has seen a significant increase over the past several years: the number of patients undergoing RARP has risen from 1% to 40% of all prostatectomies from 2001–2006 to as many as 80% in 2010. The robotic interface provides a 3D magnified view of the surgical field, intuitive instrument manipulation, motion scaling, tremor filtration, and excellent dexterity and range of motion. However, in some cases, the lack of tactile (haptic) feedback may limit the surgeon’s decision making ability in assessing malignant involvement of the neurovascular bundles. Pre-operative planning relies on nomograms based on limited clinical and prostate biopsy information. The surgical decision to spare or resect the neurovascular bundles is based on clinical information which is not spatially or anatomically based. Advances in magnetic resonance imaging (MRI) may provide spatially localized information to fill this void and aid surgical planning, particularly for robotic surgeons. In this review, we discuss the potential role of pre-operative MRI in surgical planning for radical prostatectomy.

Evidence for the insufficient evaluation and undertreatment of chronic hepatitis B infection in a predominantly low‐income and immigrant population

Background and Aim:  Many physicians remain unaware of contemporary treatments for chronic hepatitis B (HBV) infection and do not treat their HBV‐infected patients or refer them for treatment. The aim of the present study was to determine the rates of laboratory evaluation and treatment of HBV infection in a predominantly low‐income and immigrant population.

In-Bore 3-T MR-guided Transrectal Targeted Prostate Biopsy: Prostate Imaging Reporting and Data System Version 2–based Diagnostic Performance for Detection of Prostate Cancer

Purpose To determine the diagnostic yield of in-bore 3-T magnetic resonance (MR) imaging-guided prostate biopsy and stratify performance according to Prostate Imaging Reporting and Data System (PI-RADS) versions 1 and 2. Materials and Methods This study was HIPAA compliant and institution review board approved. In-bore 3-T MR-guided prostate biopsy was performed in 134 targets in 106 men who (a) had not previously undergone prostate biopsy, (b) had prior negative biopsy findings with increased prostate-specific antigen (PSA) level, or (c) had a prior history of prostate cancer with increasing PSA level. Clinical, diagnostic 3-T MR imaging was performed with in-bore guided prostate biopsy, and pathology data were collected. The diagnostic yields of MR-guided biopsy per patient and target were analyzed, and differences between biopsy targets with negative and positive findings were determined. Results of logistic regression and areas under the curve were compared between PI-RADS versions 1 and 2. Results Prostate cancer was detected in 63 of 106 patients (59.4%) and in 72 of 134 targets (53.7%) with 3-T MR imaging. Forty-nine of 72 targets (68.0%) had clinically significant cancer (Gleason score ≥ 7). One complication occurred (urosepsis, 0.9%). Patients who had positive target findings had lower apparent diffusion coefficient values (875 × 10-6 mm2/sec vs 1111 × 10-6 mm2/sec, respectively; P < .01), smaller prostate volume (47.2 cm3 vs 75.4 cm3, respectively; P < .01), higher PSA density (0.16 vs 0.10, respectively; P < .01), and higher proportion of PI-RADS version 2 category 3-5 scores when compared with patients with negative target findings. MR targets with PI-RADS version 2 category 2, 3, 4, and 5 scores had a positive diagnostic yield of three of 23 (13.0%), six of 31 (19.4%), 39 of 50 (78.0%), and 24 of 29 (82.8%) targets, respectively. No differences were detected in areas under the curve for PI-RADS version 2 versus 1. Conclusion In-bore 3-T MR-guided biopsy is safe and effective for prostate cancer diagnosis when stratified according to PI-RADS versions 1 and 2. ©RSNA, 2016.