Prevalence of accessory sacroiliac joint anatomy and associated clinical features.

OBJECTIVE: The accessory sacroiliac joint (ASIJ) is the most common sacroiliac joint anatomical variant; however, its literature-reported prevalence is inconsistent. Previous CT-based studies of the ASIJ have used thick axial slices, which may not adequately detail ASIJ anatomy. The aims of this study are to (1) evaluate ASIJ prevalence and radiographic features in a large age- and sex-balanced cohort using thin-section CT and (2) determine associations between ASIJ anatomy, patient features, and treatment strategies. MATERIALS AND METHODS: Thin-section CTs (0.75 to 2.00 mm) of the pelvis from 800 patients were reviewed by two musculoskeletal radiologists. Degree of degenerative change and ankylosis at ASIJs were detailed. The EMR was used to capture demographics, lower back or sacroiliac joint symptoms, and treatments. RESULTS: The ASIJ was present in 25.8% of patients and bilateral in 53.3% of those with any ASIJ. ASIJs were more common at the S2 than S1 neural foramen level (75.7% and 27.2%). There was a statistically significant difference between age and presence of any ASIJ anatomy (mean (SD) 69.0 (19.8) with ASIJ versus 55.9 (22.1) years without ASIJ). Degenerative changes and ankylosis were found in 93.5% and 20.3% of ASIJs, respectively. There was a higher odds ratio of having received a sacroiliac joint corticosteroid injection in those with ASIJ anatomy. CONCLUSION: Radiologists should be familiar with the ASIJ and consider its age-related association, propensity to show ASIJ degenerative change, and ability to serve as a potential pain generator. Steroid injections may be considered for diagnostic and therapeutic purposes.

Practice Patterns of Preoperative Breast and Axillary Localizations.

The goal of this survey was to study the current trends of preoperative breast and axillary needle localizations and to understand factors that affect these practice patterns. A 14-question survey was sent out to Society of Breast Imaging physicians on our institution's survey platform with a web link. Survey responses were summarized using percentages or means, and Pearson's chi square test and analysis of variance tests were used for association. The survey response rate was 401 of 2097 (19.1%). Of these responses, 124 of 401 (30.9%) were in academic practice, 222 of 401 (55.4%) in private practice with breast specialization, 24 of 401 (6.0%) in private practice without breast specialization, and 31 of 401 (7.7%) in other types of practices. The use of radioactive seeds was significantly correlated with the practice type, with academic practices more likely to use radioactive seeds. Practices with a higher number of radiologists reading mammography and a higher number of radiologists with breast fellowship training were more likely to use wireless localization devices. Additionally, there was a significant positive correlation between the number of fellowship-trained breast radiologists in a practice, and modalities utilized for localizing breast lesions. This study demonstrates that localization methods for breast and axillary lesions vary across practice types. Academic practices are more likely to utilize wireless localization devices. These findings suggest that there may be barriers for smaller and less specialized practices in implementing the use of newer localization methods.

Breast cancers observed in transplant patients in a single institution.

OBJECTIVE: Document occurrence of breast cancer in females after liver, kidney, or pancreas transplantation seen at a tertiary medical center. METHODS: Medical records of adult female patients with liver, kidney, or pancreas transplants from 1/1/1995 to 4/4/2014 were retrospectively reviewed. Patients with a history of breast cancer, no mammogram post-transplant, or no research authorization were excluded. Mammogram findings and pathology results were reviewed and recorded. Cancer rates could not be measured in patients followed up outside the institution. Descriptive statistics summarized the cohort. Occurrence rates were estimated using Poisson regression. RESULTS: 1095 women were included and 33 were diagnosed with breast cancer post-transplant. Median age at diagnosis was 58 years. Average interval from transplant to cancer diagnosis was 82.6 months. Observed occurrence of invasive and in-situ breast cancer (reported as per 100,000 person-years [95% confidence interval]) was 353 [243-496]. Liver transplant patients showed the lowest rate (181 [95% CI 73-372]), vs. kidney (476 [305-708]) or pancreas (467 [57-1688]). Patients with the highest breast density showed increased occurrence despite younger age (1001 [367-2178]) compared to those with lower breast density (range 239 [109-454] to 372 [186-666]). CONCLUSIONS: Female patients after organ transplant experienced increased breast cancer occurrence in this observational study. Those who developed breast cancer also had increased breast density. The findings underscore the importance of breast cancer screening in this population.

Clinical evaluation of a new adaptive iterative metal artifact reduction method in whole-body low-dose CT skeletal survey examinations.

OBJECTIVE: To evaluate a new adaptive iterative metal artifact reduction algorithm (AiMAR) in whole-body low-dose CT (WBLDCT) skeletal survey examinations. METHODS: Projection data were retrospectively obtained from 25 clinical WBLDCT skeletal survey patients, each with two types of metal implants. Images were reconstructed with bone and soft tissue kernels using four settings-original and AiMAR with strengths of 2, 4, and 5. All images were anonymized and randomized for a reader study, where three musculoskeletal radiologists independently determined the overall ranking of all series based on diagnostic quality, and local scoring of metal artifact and anatomy visualization for each implant. Quantitative image noise analysis was performed in areas close to the implants. Intraclass correlation coefficients (ICC) and Krippendorff's alpha were computed for inter-rater reliability. RESULTS: AiMAR 4 was ranked the highest for 64.3% of the series across eight types of implants. For local scoring task, AiMAR 4 showed better metal artifact and anatomy visualization than the original and AiMAR 2. AiMAR 4 was comparable in anatomy visualization but inferior to AiMAR 5 in metal artifact scores. AiMAR 4 led to 56.3% noise reduction around the implant areas compared with the original images, and AiMAR 5 68.1% but also resulted in anatomy blurring in 40% of the implants. ICC and Krippendorff's alpha revealed at least substantial reliability in the local scores among the readers. CONCLUSIONS: AiMAR was evaluated in WBLDCT skeletal surveys. AiMAR 4 demonstrated the highest overall quality ranking and improved local scores with noise reduction around implant areas.

Outcomes of solitary dilated breast ducts in symptomatic and asymptomatic patients.

OBJECTIVE: The purpose of this study is to assess the outcomes of symptomatic and asymptomatic solitary dilated ducts detected on mammography, ultrasound, and MRI. METHODS: All cases of isolated solitary dilated ducts between January 1, 2009 and December 31, 2016 in non-lactating females were reviewed. Clinical data, including patient's age, breast cancer history, and pathology results were collected. Imaging was reviewed, and indication for the exam, breast density, maximum diameter of the dilated duct on ultrasound, presence of an intraductal mass, presence of intraductal vascularity, presence of intraductal echogenicity, and subareolar or peripheral location of the dilated duct were recorded. RESULTS: 87 cases of solitary dilated ducts were assessed in this study, of which 3 were malignant, resulting in a positive predictive value of 3.5% (3/87). No malignancy was identified in asymptomatic screening patients. The three malignant cases were seen in patients presenting with a palpable lump (n = 1) or bloody nipple discharge (n = 2). There was a statistically significant association observed between the dilated duct diameter (p = 0.049) and presence of intraductal vascularity (p = 0.0005) with presence of malignancy. CONCLUSION: Rate of malignancy is low in solitary dilated ducts, especially among asymptomatic patients. Patient's presenting with clinical symptoms, larger dilated duct diameters, and/or intraductal vascularity may require additional evaluation including biopsy to exclude malignancy. ADVANCES IN KNOWLEDGE: Clinical and imaging factors can assist in better identifying patients with solitary dilated ducts who should undergo biopsy.

State-Wide Genomic and Epidemiological Analyses of Vancomycin-Resistant Enterococcus faecium in Tasmania's Public Hospitals.

From 2015 onwards, the number of vancomycin-resistant Enterococcus faecium (VREfm) isolates increased in Tasmania. Previously, we examined the transmission of VREfm at the Royal Hobart Hospital (RHH). In this study, we performed a state-wide analysis of VREfm from Tasmania's four public acute hospitals. Whole-genome analysis was performed on 331 isolates collected from screening and clinical specimens of VREfm. In silico multi-locus sequence typing (MLST) was used to determine the relative abundance of broad sequence types (ST) across the state. Core genome MLST (cgMLST) was then applied to identify potential clades within the ST groupings followed by single-nucleotide polymorphic (SNP) analysis. This work revealed that differences in VREfm profiles are evident between the state's two largest hospitals with the dominant vanA types being ST80 at the RHH and ST1421 at Launceston General Hospital (LGH). A higher number of VREfm cases were recorded at LGH (n = 54 clinical, n = 122 colonization) compared to the RHH (n = 14 clinical, n = 67 colonization) during the same time period, 2014-2016. Eleven of the clinical isolates from LGH were vanA and belonged to ST1421 (n = 8), ST1489 (n = 1), ST233 (n = 1), and ST80 (n = 1) whereas none of the clinical isolates from the RHH were vanA. For the recently described ST1421, cgMLST established the presence of individual clusters within this sequence type that were common to more than one hospital and that included isolates with a low amount of SNP variance (≤16 SNPs). A spatio-temporal analysis revealed that VREfm vanA ST1421 was first detected at the RHH in 2014 and an isolate belonging to the same cgMLST cluster was later collected at LGH in 2016. Inclusion of isolates from two smaller hospitals, the North West Regional Hospital (NRH) and the Mersey Community Hospital (MCH) found that ST1421 was present in both of these institutions in 2017. These findings illustrate the spread of a recently described sequence type of VREfm, ST1421, to multiple hospitals in an Australian state within a relatively short time span.

Emergence of Vancomycin-Resistant Enterococcus faecium at an Australian Hospital: A Whole Genome Sequencing Analysis.

In 2015, a marked increase in vancomycin-resistant Enterococcus faecium (VREfm) isolation was detected at the Royal Hobart Hospital, Australia. The primary objective of this work was to examine the dynamics of VREfm transmission using whole genome data mapped to public health surveillance information. Screening and clinical isolates of VREfm from patients were typed for the specific vancomycin-resistance locus present. Of total isolates collected from 2014-2016 (n = 222), 15.3% and 84.7% harboured either the vanA or the vanB vancomycin-resistance locus, respectively. Whole-genome sequencing of 80 isolates was performed in conjunction with single-nucleotide polymorphic (SNP) analysis and in silico multi-locus sequence typing (MLST). Among the isolates sequenced, 5 phylogenetic clades were identified. The largest vanB clade belonged to MLST sequence type ST796 and contained clinical isolates from VREfm infections that clustered closely with isolates from colonised patients. Correlation of VREfm genotypes with spatio-temporal patient movements detected potential points of transmission within the hospital. ST80 emerged as the major vanA sequence type for which the most likely index case of a patient cluster was ascertained from SNP analyses. This work has identified the dominant clones associated with increased VREfm prevalence in a healthcare setting, and their likely direction of transmission.

Imaging Appearance of Advanced Chronic Adhesive Arachnoiditis: A Retrospective Review.

OBJECTIVE: Chronic adhesive arachnoiditis (CAA) is rare and has potentially devastating clinical consequences. The objective of this article is to review the clinical features of CAA and describe its appearance on imaging, to increase radiologists' awareness of this challenging diagnosis. MATERIALS AND METHODS: Twenty-nine cases of advanced CAA seen at our institution over 18 years (1995-2013) were retrospectively reviewed. Chart review was performed, with attention given to data on clinical presentation, suspected cause, and interventions performed. All patients underwent MRI, and seven patients also underwent CT myelography. Clinical and imaging features were evaluated and categorized. RESULTS: The 29 patients ranged in age from 23 to 96 years and included 11 women and 18 men. Suspected underlying causative factors included trauma (n = 10), prior surgery (n = 9), nontraumatic subarachnoid hemorrhage (n = 7), infection (n = 3), myelography with iophendylate used as contrast medium (n = 1), Guillain-Barré syndrome (n = 1), ankylosing spondylitis (n = 1), and unknown causes (n = 1). Imaging characteristics include loculated CSF collections (n = 23), nerve root clumping, enhancement, and displacement (n = 15), cord swelling with increased T2 signal (n = 12), arachnoid septations (n = 11), cord atrophy (n = 6), syrinx (n = 5), and intrathecal calcifications (n = 3). Ten patients underwent surgical procedures, and most had only brief clinical improvement. CONCLUSION: CAA is a rare cause of devastating neurologic symptoms and chronic pain. The imaging features of CAA range from subtle to severe. Advanced arachnoiditis can present with spinal cord swelling and syrinx formation, which can mimic other disease processes. Inclusion of advanced CAA in the differential diagnosis can prevent unnecessary interventions.

Cross-sectional imaging to evaluate the extent of regional nodal disease in breast cancer patients undergoing neoadjuvant systemic therapy.

PURPOSE: Cross-sectional imaging often is performed in breast cancer patients undergoing neoadjuvant systemic therapy (NST) and may identify level III axillary and extra-axillary nodal disease. Our aim was to investigate associations of radiologic nodal staging with pathological N (pN) stage at operation and to explore how this might aid surgical and radiotherapy treatment planning. MATERIALS AND METHODS: With IRB approval, we reviewed pre-treatment breast MRI, PET/CT, and CT imaging and clinicopathologic data on 348 breast cancer patients with imaging available for review undergoing NST followed by operation at our institution 1/2008-9/2013. We defined abnormal lymph node findings on MRI, CT, and PET/CT to include cortical thickening, FDG-avidity and loss of fatty hilum. Patients were assigned a radiologic nodal (rN) stage based on imaging findings. Statistical analysis was performed using JMP 10.1 software RESULTS: Pre-NST imaging included axillary ultrasound in 338 patients (97%), breast MRI in 305 (88%) and PET/CT or CT in 215 (62%). 213 patients (61%) were biopsy-proven axillary lymph node-positive (LN+) pre-treatment. cT stage was T1 in 9%, T2 in 49%, T3 in 29%, T4 in 12%; median tumor size was 4cm. Pre-treatment rN stage across all the patients was rN0 in 86 (25%), rN1 in 173 (50%), and rN3 in 89 (26%). rN3 disease included level III axillary, supraclavicular and suspicious internal mammary lymph nodes in 47 (53%), 32 (37%) and 45 (52%), respectively. Of patients LN+ at diagnosis, 78 (37%) were rN3. After NST, 162 patients (47%) were node-positive at operation with a median (mean) of 3 (5.9±0.4) positive lymph nodes including 128 of 213 (60%) LN+ at diagnosis. Pre-NST rN stage correlated with the likelihood and extent of axillary disease at operation, p=0.002. Fifty four of 89 rN3 patients (61%) were node-positive at operation with a median (mean) of 5 (8±1) positive nodes. rN3 patients had larger nodal metastases (median 9 vs 6mm) and more frequent extranodal extension (61% vs 43%) than rN0/rN1 patients, both p<0.03. CONCLUSIONS: Information on rN stage from pre-NST cross-sectional imaging informs the likelihood and extent of axillary nodal disease at operation. This information may be used for surgical and radiotherapy treatment planning and to inform patient expectations.

Central nervous system imaging findings of hemophagocytic syndrome.

We present a rare case of intracranial involvement in hemophagocytic lymphohistiocytosis (HLH) in an adult patient. MRI features in HLH may mimic those of other neoplastic, infectious, or inflammatory disorders. Key imaging findings correlate to central nervous system inflammation and include diffuse leptomeningeal enhancement, white matter changes with variable enhancement, hemorrhage, and restricted diffusion. Recognition of the imaging characteristic in correlation with clinical presentation, laboratory values, and biopsy findings is essential for making a correct diagnosis.

Genetic and molecular predictors of high vancomycin MIC in Staphylococcus aureus bacteremia isolates.

An elevated vancomycin MIC is associated with poor outcomes in Staphylococcus aureus bacteremia (SAB) and is reported in patients with methicillin-susceptible S. aureus (MSSA) bacteremia in the absence of vancomycin treatment. Here, using DNA microarray and phenotype analysis, we investigated the genetic predictors and accessory gene regulator (agr) function and their relationship with elevated vancomycin MIC using blood culture isolates from a multicenter binational cohort of patients with SAB. Specific clonal complexes were associated with elevated (clonal complex 8 [CC8] [P < 0.001]) or low (CC22 [P < 0.001], CC88 [P < 0.001], and CC188 [P = 0.002]) vancomycin MIC. agr dysfunction (P = 0.014) or agr genotype II (P = 0.043) were also associated with an elevated vancomycin MIC. Specific resistance and virulence genes were also linked to an elevated vancomycin MIC, including blaZ (P = 0.002), sea (P < 0.001), clfA (P < 0.001), splA (P = 0.001), and the arginine catabolic mobile element (ACME) locus (P = 0.02). These data suggest that inherent organism characteristics may explain the link between elevated vancomycin MICs and poor outcomes in patients with SAB, regardless of the antibiotic treatment received. A consideration of clonal specificity should be included in future research when attempting to ascertain treatment effects or clinical outcomes.

Treatment options for New Delhi metallo-beta-lactamase-harboring enterobacteriaceae.

The New Delhi metallo-ß-lactamase gene (bla(NDM-1)) has emerged as a worldwide concern among isolates of Enterobacteriaceae. Its epidemiology is been strongly associated with travel and healthcare on the Indian Subcontinent. We report two cases of urinary tract infection with Enterobacteriaceae harboring a bla(NDM-1). Both cases presented as infection in community-dwelling individuals in Australia and were associated with travel to the Indian Subcontinent. One isolate of Escherichia coli harbored the previously undescribed enzyme variant bla(NDM-3), differing from bla(NDM-1) by a single nonsynonymous SNP conferring a putative peptide sequence change at the 95th position (ASP→ASN). The second was an Enterobacter cloacae harboring bla(NDM-1). Further genetic characterization included identification of additional ß-lactamase and aminoglycoside resistance genes. Legacy antimicrobials were used for treatment. Oral therapy with nitrofurantoin was successful in one case, while combination of colistin and rifampicin was required in the second patient. Such infection, due to extensively drug-resistant pathogens, poses significant challenges in balancing the efficacy and toxicity of potential antimicrobial therapies.

Vancomycin AUC/MIC ratio and 30-day mortality in patients with Staphylococcus aureus bacteremia.

A ratio of the vancomycin area under the concentration-time curve to the MIC (AUC/MIC) of ≥ 400 has been associated with clinical success when treating Staphylococcus aureus pneumonia, and this target was recommended by recently published vancomycin therapeutic monitoring consensus guidelines for treating all serious S. aureus infections. Here, vancomycin serum trough levels and vancomycin AUC/MIC were evaluated in a "real-world" context by following a cohort of 182 patients with S. aureus bacteremia (SAB) and analyzing these parameters within the critical first 96 h of vancomycin therapy. The median vancomycin trough level at this time point was 19.5 mg/liter. There was a significant difference in vancomycin AUC/MIC when using broth microdilution (BMD) compared with Etest MIC (medians of 436.1 and 271.5, respectively; P < 0.001). Obtaining the recommended vancomycin target AUC/MIC of ≥ 400 using BMD was not associated with lower 30-day all-cause or attributable mortality from SAB (P = 0.132 and P = 0.273, respectively). However, an alternative vancomycin AUC/MIC of >373, derived using classification and regression tree analysis, was associated with reduced mortality (P = 0.043) and remained significant in a multivariable model. This study demonstrated that we obtained vancomycin trough levels in the target therapeutic range early during the course of therapy and that obtaining a higher vancomycin AUC/MIC (in this case, >373) within 96 h was associated with reduced mortality. The MIC test method has a significant impact on vancomycin AUC/MIC estimation. Clinicians should be aware that the current target AUC/MIC of ≥ 400 was derived using the reference BMD method, so adjustments to this target need to be made when calculating AUC/MIC ratio using other MIC testing methods.

Antibiotic choice may not explain poorer outcomes in patients with Staphylococcus aureus bacteremia and high vancomycin minimum inhibitory concentrations.

BACKGROUND: There are concerns about reduced efficacy of vancomycin in patients with Staphylococcus aureus bacteremia (SAB), especially when the minimum inhibitory concentration (MIC) nears the upper limit of the susceptible range. METHODS: We examined the relationship between antibiotic treatment, 30-day mortality, and microbiologic parameters in a large Australasian cohort of patients with SAB. RESULTS: We assessed 532 patients with SAB from 8 hospitals. All patients with methicillin-resistant S. aureus (MRSA) bacteremia were treated with vancomycin, and patients with methicillin-susceptible S. aureus (MSSA) bacteremia received either flucloxacillin or vancomycin. Increasing vancomycin MIC was associated with increased mortality in vancomycin-treated patients. However, even in patients with MSSA bacteremia treated with flucloxacillin, mortality was also higher if the vancomycin Etest MIC of their isolate was >1.5 µg/mL, compared with those with lower MIC isolates (26.8% vs 12.2%; P < .001). After adjustment in a multivariate model, age, hospital-onset SAB and vancomycin MIC were independently associated with mortality, but methicillin resistance and antibiotic choice were not. CONCLUSIONS: We have confirmed an association between higher vancomycin MIC and increased mortality in patients with SAB, but surprisingly this relationship was not related to the antibiotic treatment received, suggesting that the use of vancomycin per se is not responsible for the poorer outcome.

Evaluation of the Clearview Clostridium difficile Toxin A Test and various selective culture media in comparison with the cytotoxin assay for the diagnosis of Clostridium difficile-associated diarrhoea.

AIM: Clostridium difficile is the major pathogen associated with nosocomial diarrhoea. We evaluated the performances of a commercially available toxin A enzyme immunoassay (EIA; Clearview C. difficile Toxin A Test), culture and tissue culture cytotoxin assay in the diagnosis of C. difficile-associated diarrhoea. METHODS: Comparative test performance was determined from data obtained from 166 faecal samples. The initial analysis compared the performance of toxin A EIA and culture with that of cytotoxin assay, this being defined as a 'laboratory gold standard'. A second analysis compared the individual performance of the toxin A EIA, culture and cytotoxin assay using a combined clinical and laboratory diagnostic assessment as a 'clinical gold standard'. In a parallel, study three selective culture media were compared. RESULTS: From the initial analysis, the sensitivity and specificity of the methods were, respectively, 84.6 and 65.4% for the toxin A EIA, and 38.5 and 93.5% for culture. From the second analysis, the sensitivity and specificity of the methods were, respectively, 100 and 67.5% for the toxin A EIA, 63.6 and 96.7% for culture and 72.7 and 98.0% for cytotoxin assay. Media containing d-cycloserine 250mg/L and cefoxitin 8mg/L performed best, growing 88.2% of the isolates. CONCLUSION: The toxin A EIA we evaluated had poor specificity in the diagnosis of C. difficile-associated diarrhoea. We conclude that in our laboratory the combination of culture and cytotoxin assay is a preferred approach to the diagnosis of C. difficile-associated diarrhoea.