Ultrasound-guided lymph node fine-needle aspiration for evaluating post-vaccination germinal center responses in humans.

The lymph node (LN) is a critical biological site for immune maturation after vaccination as it includes several cell populations critical for priming the antibody response. Here, we present a protocol for sampling the LN and isolating cell populations to evaluate immunogens targeting germline cells. We describe steps for media and tube preparation and sample collection using an ultrasound-guided LN fine-needle aspiration procedure. This protocol is safe, quick, low-cost, and less invasive than excisional biopsy. For complete details on the use and execution of this protocol, please refer to Leggat et al. (2022).1.

Intra-examination agreement between multi-echo gradient echo and confounder-corrected chemical shift-encoded MR sequences for R2* estimation as a biomarker of liver iron content in patients with a wide range of T2*/R2* and proton density fat fraction values.

PURPOSE: To investigate the intra-examination agreement between multi-echo gradient echo (MEGE) and confounder-corrected chemical shift-encoded (CSE) sequences for liver T2*/R2* estimations in a wide range of T2*/R2* and proton density fat fraction (PDFF) values. Exploratorily, to search for the T2*/R2* value where the agreement line breaks and examine differences between regions of low and high agreement. METHODS: Consecutive patients at risk for liver iron overload who underwent MEGE and CSE sequences within the same exam at 1.5 T were retrospectively selected. Regions of interest were drawn in the right and one in the left liver lobes on post-processed images for R2*(sec-1) and PDFF (%) estimation. Agreement between MEGE-R2* and CSE-R2* was evaluated using intra-class correlation coefficient (ICC) and Bland-Altman analysis. 95% confidence intervals (CI) were computed. Segment-and-regression analysis was performed to find the point where the agreement between sequences is interrupted. Regions of low and high agreement were examined using tree-based partitioning analyses. RESULTS: 49 patients were included. Mean MEGE-R2* was 94.2 s-1 (range: 31.0-737.1) and mean CSE-R2* 87.7 (29.7-748.1). Mean CSE-PDFF was 9.12% (0.1-43.3). Agreement was strong for R2* estimations (ICC: 0.992,95%CI 0.987,0.996), but the relation was nonlinear and possibly heteroskedastic. Lower agreement occurred when MEGE-R2* > 235 s-1, with MEGE-R2* values consistently lower than CSE-R2*. Higher agreement was observed when PDFF < 14%. CONCLUSION: MEGE-R2* and CSE-R2* strongly agree, though at higher iron content, MEGE-R2* is consistently lower than CSE-R2*. In this preliminary dataset, a breaking point for agreement was found at R2* > 235. Lower agreement was observed in patients with moderate to severe liver steatosis.

MRI for Liver Iron Quantification: Concepts and Current Methods.

Liver Iron content is best correlated to total body iron stores and is thus the organ of choice for evaluation in iron overload diseases. Liver biopsy was the historic standard for iron evaluation, but the evaluation is localized, comes with increased risks due to its invasiveness, and is costly. MRI is now widely used for liver iron evaluation. The superparamagnetic properties of iron cause a disturbance in magnetic resonance imaging, which can be evaluated with various techniques. These include signal intensity ratio (SIR), T2 relaxometry, T2* relaxometry, and Dixon-based solutions. Each of the methods has its own advantages and disadvantages, and factors such as availability, ease of use, accuracy, reproducibility, and cost can all play a role in the ultimate technique used for liver iron quantification. Quantitative susceptibility mapping, and ultrashort TE sequences are promising supplemental methods, but are primarily used as research sequences. These may become more clinically accepted in the near future. Dual energy CT is also being explored as an alternative but is still in the nascent stages. Overall, accurate liver iron concentration is feasible with the current tools available at most MR imaging centers and is highly valuable for evaluation of iron overload diseases.

Circulating and Intratumoral Adrenal Androgens Correlate with Response to Abiraterone in Men with Castration-Resistant Prostate Cancer.

PURPOSE: In metastatic castration-resistant prostate cancer (mCRPC) low serum androgens prior to starting abiraterone acetate (AA) is associated with more rapid progression. We evaluated the effect of AA on androgens in castration-resistant prostate cancer (CRPC) metastases and associations of intratumoral androgens with response. EXPERIMENTAL DESIGN: We performed a phase II study of AA plus prednisone in mCRPC. The primary outcome was tissue testosterone at 4 weeks. Exploratory outcomes were association of steroid levels and genomic alterations with response, and escalating AA to 2,000 mg at progression. RESULTS: Twenty-nine of 30 men were evaluable. Testosterone in metastatic biopsies became undetectable at 4 weeks (P < 0.001). Serum and tissue dehydroepiandrosterone sulfate (DHEAS) remained detectable in many patients and was not increased at progression. Serum and tissue DHEAS in the lowest quartile (pretreatment), serum DHEAS in the lowest quartile (4 weeks), and undetectable tissue DHEAS (on-therapy) associated with rapid progression (20 vs. 48 weeks, P = 0.0018; 20 vs. 52 weeks, P = 0.0003; 14 vs. 40 weeks, P = 0.0001; 20 vs. 56 weeks, P = 0.02, respectively). One of 16 men escalating to 2,000 mg had a 30% PSA decline; 13 developed radiographic progression by 12 weeks. Among patients with high serum DHEAS at baseline, wild-type (WT) PTEN status associated with longer response (61 vs. 33 weeks, P = 0.02). CONCLUSIONS: Low-circulating adrenal androgen levels are strongly associated with an androgen-poor tumor microenvironment and with poor response to AA. Patients with CRPC with higher serum DHEAS levels may benefit from dual androgen receptor (AR)-pathway inhibition, while those in the lowest quartile may require combinations with non-AR-directed therapy.

Carcinoma of unknown primary with hepatic metastases: a need of judicious and contemplative diagnostic algorithm.

Carcinoma of Unknown Primary presenting primarily as hepatic metastases encompasses a dismal subgroup of tumors with a median survival of 5.9 months. Adenocarcinoma is the most common histological subtype identified upon biopsy and the primary tumor remains undetectable in the majority of cases despite extensive workup. It is important to have a validated and standardized algorithm to follow these tumors to avoid unnecessary tests, as the wishes and health status of the patient represent the principal concerns. The purpose of this paper is to briefly review the current literature on carcinoma of unknown primary with hepatic metastases and propose a standardized diagnostic approach.

"I was seen by a radiologist, but unfortunately I can't remember the name and I still have questions. What should I do?" Radiologists should give thoughts to improve service professionalism and patient esteem.

BACKGROUND: The aim of the study is to investigate how well patients remember the radiologist's name after a radiological examination, and whether giving the patient a business card improves the patient's perception of the radiologist's professionalism and esteem. METHODS: In this prospective and randomized two-centre study, a total of 141 patients with BI-RADS 1 and 2 scores were included. After screening examination comprising mammography and ultrasound by a radiologist, 71 patients received a business card (group 1), while 70 received no business card (group 2). Following the examination, patients were questioned about their experiences. RESULTS: The patients in group 1 could remember the name of the radiologist in 85% of cases. The patients in group 2, in contrast, could only remember the name in 7% of cases (p < 0.001). 90% of the patients in group 1 believed it was very important that they are able to contact the radiologist at a later time, whereas only 76% of patients in group 2 felt that this was a very important service (p < 0.025). A total of 87% of the patients in group 1 indicated that they would contact the radiologist if they had any questions whereas 73% of the patients in group 2 would like to contact the radiologist but were not able to do so, because they could not remember the name (p < 0.001). All questions were analysed with a Cochran-Mantel-Haenszel (CMH) test that took study centre as stratification into account. In some cases, two categories were collapsed to avoid zero cell counts. CONCLUSIONS: Using business cards significantly increased the recall of the radiologist's name and could be an important tool in improving the relationships between patients and radiologists and enhancing service professionalism. TRIAL REGISTRATION: We have a general approval from our ethics committee. The patients have given their consent to this study.

Chronic Pancreatitis or Pancreatic Tumor? A Problem-solving Approach.

Certain inflammatory pancreatic abnormalities may mimic pancreatic ductal adenocarcinoma at imaging, which precludes accurate preoperative diagnosis and may lead to unnecessary surgery. Inflammatory conditions that may appear masslike include mass-forming chronic pancreatitis, focal autoimmune pancreatitis, and paraduodenal pancreatitis or "groove pancreatitis." In addition, obstructive chronic pancreatitis can mimic an obstructing ampullary mass or main duct intraductal papillary mucinous neoplasm. Secondary imaging features such as the duct-penetrating sign, biliary or main pancreatic duct skip strictures, a capsulelike rim, the pancreatic duct-to-parenchyma ratio, displaced calcifications in patients with chronic calcific pancreatitis, the "double duct" sign, and vessel encasement or displacement can help to suggest the possibility of an inflammatory mass or a neoplastic process. An awareness of the secondary signs that favor a diagnosis of malignant or inflammatory lesions in the pancreas can help the radiologist to perform the differential diagnosis and determine the degree of suspicion for malignancy. Repeat biopsy or surgical resection may be necessary to achieve an accurate diagnosis and prevent unnecessary surgery for inflammatory conditions. Online supplemental material and DICOM image stacks are available for this article. ©RSNA, 2019.

Serum albumin, total bilirubin, and patient age are independent confounders of hepatobiliary-phase gadoxetate parenchymal liver enhancement.

PURPOSE: To identify independent confounding variables of gadoxetate-enhanced hepatobiliary-phase liver MRI using multiple regression analysis. MATERIALS AND METHODS: The institutional review board generally approved retrospective analyses and all patients provided written informed consent. One hundred ten patients who underwent a standardized 3.0-T gadoxetate-enhanced liver MRI between November 2008 and June 2013 were retrospectively reviewed. The gadoxetate liver enhancement normalized to enhancement in the erector spinae muscle (relative signal enhancement, SE) was related to biochemical laboratory parameters and descriptive patient characteristics (patient age, body mass index) using non-parametric univariate correlation analysis followed by a multiple linear regression model. RESULTS: Using univariate statistics, relative SE was inversely correlated with patient age, ALP, AST, total bilirubin, gamma-glutamyltransferase, INR, model of end-stage liver disease score, and proportionally with albumin and hemoglobin (all p < 0.01). In a multiple regression analysis, total bilirubin (p = 0.001), serum albumin (p = 0.016), and patient age (p = 0.018) were independently correlated with relative liver SE (n = 110). CONCLUSION: A multiple regression analysis showed that high total bilirubin, low serum albumin, or advanced age was associated with low hepatobiliary-phase gadoxetate parenchymal liver enhancement. In these patients, the lower contrast-to-noise ratio might impair diagnostic evaluation of non-enhancing liver lesions (e.g., HCC, liver metastasis). KEY POINTS: • A multiple regression analysis identified independent confounding variables of hepatobiliary-phase gadoxetate liver enhancement. • High bilirubin, low albumin, or advanced age was associated with low enhancement. • Diagnostic evaluation might be hampered in these patients.

An MRI-guided HIFU-triggered wax-coated capsule for supertargeted drug release: a proof-of-concept study.

BACKGROUND: Externally controlling and monitoring drug release at a desired time and location is currently lacking in the gastrointestinal tract. The aim of the study was to develop a thermoresponsive wax-coated capsule and to trigger its release upon applying a magnetic resonance imaging (MRI)-guided high-intensity focused ultrasound (HIFU) pulse. METHODS: Capsules containing a lyophilised gadolinium-based contrast agent (GBCA) were coated with a 1:1 (mass/mass) mixture of lanolin and cetyl alcohol (melting point ≈43 °C) and exposed to simulated gastric and intestinal fluids (United States Pharmacopoeia) at 37 °C for 2 and 24 h, respectively. In a HIFU gel phantom, wax-coated capsules (n = 3) were tracked based on their T1- and T2-hypointensity by 1.5-T T1- and T2-weighted MRI pre- and post-exposure to an MRI-guided HIFU pulse. RESULTS: Lanolin/cetyl alcohol-coated capsules showed high resistance to simulated gastrointestinal fluids. In a gel phantom, an MRI-guided HIFU pulse punctured the wax coating, resulting in the hydration and release of the encapsulated lyophilised GBCA and yielding a T1-hyperintense signal close to the wax-coated capsule. CONCLUSION: We provide the proof-of-concept of applying a non-invasive MRI-guided HIFU pulse to actively induce the disintegration of the wax-coated capsule, and a method to monitor the release of the cargo via T1-weighted MRI based on the hydration of an encapsulated lyophilised GBCA. The wax-coated capsule platform enables temporally and spatially supertargeted drug release via the oral route and promises to address a currently unmet clinical need for personalised local therapy in gastrointestinal diseases such as inflammatory bowel diseases and cancer.

Postpartum Bone Marrow Edema at the Sacroiliac Joints May Mimic Sacroiliitis of Axial Spondyloarthritis on MRI.

OBJECTIVE: The objective of our study was to compare MRI findings in the sacroiliac joints of postpartum women (as a model of mechanical changes) and women with known axial spondyloarthritis (as an inflammatory model). SUBJECTS AND METHODS: For this prospective multicenter age-matched, case-control study, sacroiliac joint MRI examinations of 30 healthy women (mean age, 34.0 years) in the early postpartum period (mechanical group) and 30 age-matched women (mean age, 33.8 years) with known axial spondyloarthritis (retrospective inflammatory group) were compared. Blinded to clinical information, readers assessed MR images using the following scoring systems: Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index, Berlin method, Assessment of Spondyloarthritis International Society (ASAS) criteria, and SPARCC MRI structural score. Descriptive statistics as percentages of the different findings (i.e., bone marrow edema [BME], erosion, fatty bone marrow replacement, backfill, ankylosis) and scores between groups and between delivery modes were compared. RESULTS: In the postpartum group, 63.3% (19/30) of women showed BME around the sacroiliac joints compared with 86.7% (26/30) of women in the spondyloarthritis group (based on ASAS criteria). Erosions were uncommon in the postpartum group (10.0% [3/30] postpartum vs 56.7% [17/30] spondyloarthritis). Fatty bone marrow replacement, backfill, and ankylosis were not seen in the postpartum group. In subjects with positive MRI findings for sacroiliitis based on ASAS criteria, the SPARCC MRI index (mean ± SD, 13.6 ± 14.5 vs 13.0 ± 10.7; p = 0.818) and Berlin method (4.5 ± 3.0 and 5.5 ± 3.5, p = 0.378) were not different between the postpartum and spondyloarthritis groups. Scores were not different between birth modalities. CONCLUSION: Pregnancy-induced BME at the sacroiliac joints, as a result of prolonged mechanical stress, was present in 63.3% of women who underwent MRI during the early postpartum period and may mimic sacroiliitis of axial spondyloarthritis.

Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences.

PURPOSE: To assess the performance of fat-suppressed fluid-sensitive MRI sequences compared to T1-weighted (T1w) / T2w sequences for the detection of Modic 1 end-plate changes on lumbar spine MRI. MATERIALS AND METHODS: Sagittal T1w, T2w, and fat-suppressed fluid-sensitive MRI images of 100 consecutive patients (consequently 500 vertebral segments; 52 female, mean age 74 ±â€Š7.4 years; 48 male, mean age 71 ±â€Š6.3 years) were retrospectively evaluated. We recorded the presence (yes/no) and extension (i. e., Likert-scale of height, volume, and end-plate extension) of Modic I changes in T1w/T2w sequences and compared the results to fat-suppressed fluid-sensitive sequences (McNemar/Wilcoxon-signed-rank test). RESULTS: Fat-suppressed fluid-sensitive sequences revealed significantly more Modic I changes compared to T1w/T2w sequences (156 vs. 93 segments, respectively; p < 0.001). The extension of Modic I changes in fat-suppressed fluid-sensitive sequences was significantly larger compared to T1w/T2w sequences (height: 2.53 ±â€Š0.82 vs. 2.27 ±â€Š0.79, volume: 2.35 ±â€Š0.76 vs. 2.1 ±â€Š0.65, end-plate: 2.46 ±â€Š0.76 vs. 2.19 ±â€Š0.81), (p < 0.05). Modic I changes that were only visible in fat-suppressed fluid-sensitive sequences but not in T1w/T2w sequences were significantly smaller compared to Modic I changes that were also visible in T1w/T2w sequences (p < 0.05). CONCLUSION: In conclusion, fat-suppressed fluid-sensitive MRI sequences revealed significantly more Modic I end-plate changes and demonstrated a greater extent compared to standard T1w/T2w imaging. KEY POINTS: · When the Modic classification was defined in 1988, T2w sequences were heavily T2-weighted and thus virtually fat-suppressed.. · Nowadays, the bright fat signal in T2w images masks edema-like changes.. · The conventional definition of Modic I changes is not fully applicable anymore.. · Fat-suppressed fluid-sensitive MRI sequences revealed more/greater extent of Modic I changes.. CITATION FORMAT: · Finkenstaedt T, Del Grande F, Bolog N et al. Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences. Fortschr Röntgenstr 2018; 190: 152 - 160.

Fully navigated 3 T proton magnetic resonance spectroscopy of liver metastases with inner-volume saturation.

PURPOSE: To demonstrate that fully navigated magnetic resonance spectroscopy (MRS) with inner-volume saturation (IVS) at 3 T results in high-quality spectra that permit evaluating metabolic changes in hepatic metastases without the need for patient compliance. METHODS: Nine patients with untreated, biopsy-proven large hepatic metastases (minimum diameter of 3 cm) were included. In each patient, localized proton MRS was performed in the metastatic lesion and in uninvolved liver parenchyma. To improve quality and consistency of proton MRS, navigator gating was thereby performed not only during acquisition of the spectroscopic data but also during localization imaging and throughout the preparation phases. IVS was utilized to reduce chemical shift displacement between different metabolites and to diminish flow artifacts. Metabolite quantities were normalized relative to the unsuppressed water peak and choline-containing compounds (CCC) to lipid ratios were determined. Wilcoxon signed-rank tests were used to assess differences in the amounts of lipids and CCC as well as the CCC-to-lipid ratios between liver metastases and normal-appearing liver parenchyma. RESULTS: Fully navigated point-resolved spectroscopy with IVS resulted in high-quality spectra in all patients. Navigator gating during localization imaging and spectroscopic acquisition thereby ensured a precise localization of the spectroscopic voxel. Decreased quantities of lipid and CCC were observed in metastatic tissue compared with uninvolved liver parenchyma. However, the latter trend fell short of statistical significance. Moreover, elevated levels of the CCC-to-lipid ratios were detected in metastatic tissue relative to normal-appearing liver parenchyma. CONCLUSIONS: The present study demonstrates that fully navigated MRS of the liver with IVS at 3 T allows for a precise localization of the spectroscopic voxel and results in high-quality spectra that permit evaluating liver metabolism without the need for patient compliance.

Computer-assisted evaluation of contrast kinetics for detection of hepatocellular carcinoma on magnetic resonance imaging.

The purpose of this study was to assess the use of semiquantitative contrast-enhanced parameter analysis as an objective criteria for improving the magnetic resonance (MR) evaluation of hepatocellular carcinoma (HCC) in patients with cirrhosis. Contrast-enhanced MR examination findings from 19 patients with 21 pathologically proven HCC were evaluated using a dedicated liver image postprocessing workstation. Contrast-enhancement kinetic curves were created for each lesion, and 4 enhancement parameters (arterial wash-in slope, arterial-portal slope, arterial-equilibrium slope, and portal-equilibrium slope) were defined from the signal intensity-time plots. The accuracy of each enhancement parameter for the characterization of HCC was assessed. Statistical analysis revealed that an arterial-phase wash-in slope percentage value >1.35 per sec had a sensitivity of 86%, a specificity of 71%, and an accuracy of 79% for the correct characterization of HCC, whereas an arterial-equilibrium wash-out slope percentage value<0.05 per sec had a sensitivity of 86%, a specificity of 81%, and an accuracy of 83%. Although there were significant differences among all groups, the greatest accuracy for differentiation based on receiver operating curve analysis appears to be with arterial and arterial-equilibrium phases. Semiquantitative analysis of lesion contrast kinetics could provide objective parameters to improve the characterization of HCC on contrast-enhanced MR images.

Hepatocellular carcinoma in the noncirrhotic liver.

OBJECTIVE: Hepatocellular carcinomas (HCCs) that arise in noncirrhotic livers have several histologic and biochemical features that distinguish them from HCCs occurring in the setting of cirrhosis. Because the presentation, management, and prognosis of these entities are distinct, the accurate preoperative characterization of these lesions is of great clinical significance. We review the pathogenesis, imaging appearance, and clinical implications of noncirrhotic HCCs as they pertain to the clinical radiologist. CONCLUSION: HCCs that develop in noncirrhotic patients have distinct etiologic, cytogenetic, histopathologic, and clinical features. Despite a larger tumor burden at the time of HCC diagnosis, noncirrhotic patients with HCC have better overall survival and disease-free survival than cirrhotic patients with HCC. Knowledge of the precise clinical and imaging features of this entity and of other diagnostic considerations for the noncirrhotic liver is essential for improved patient care.

Intrabiliary RF heat-enhanced local chemotherapy of a cholangiocarcinoma cell line: monitoring with dual-modality imaging--preclinical study.

PURPOSE: To determine whether magnetic resonance (MR) imaging heating guidewire-mediated radiofrequency (RF) hyperthermia could enhance the therapeutic effect of gemcitabine and 5-fluorouracil (5-FU) in a cholangiocarcinoma cell line and local deposit doses of chemotherapeutic drugs in swine common bile duct (CBD) walls. MATERIALS AND METHODS: The animal protocol was approved by the institutional animal care and use committee. Green fluorescent protein-labeled human cholangiocarcinoma cells and cholangiocarcinomas in 24 mice were treated with (a) combination therapy with chemotherapy (gemcitabine and 5-FU) plus RF hyperthermia, (b) chemotherapy only, (c) RF hyperthermia only, or (d) phosphate-buffered saline. Cell proliferation was quantified, and tumor changes over time were monitored with 14.0-T MR imaging and optical imaging. To enable further validation of technical feasibility, intrabiliary local delivery of gemcitabine and 5-FU was performed by using a microporous balloon with (eight pigs) or without (eight pigs) RF hyperthermia. Chemotherapy deposit doses in the bile duct walls were quantified by means of high-pressure liquid chromatography. The nonparametric Mann-Whitney U test and the paired-sample Wilcoxon signed rank test were used for data analysis. RESULTS: Combination therapy induced lower mean levels of cell proliferation than chemotherapy only and RF hyperthermia only (0.39 ± 0.13 [standard deviation] vs 0.87 ± 0.10 and 1.03 ± 0.13, P < .001). Combination therapy resulted in smaller relative tumor volume than chemotherapy only and RF hyperthermia only (0.65 ± 0.03 vs 1.30 ± 0.021 and 1.37 ± 0.05, P = .001). Only in the combination therapy group did both MR imaging and optical imaging show substantial decreases in apparent diffusion coefficients and fluorescent signals in tumor masses immediately after the treatments. Chemotherapy quantification showed a higher average drug deposit dose in swine CBD walls with intrabiliary RF hyperthermia than without it (gemcitabine: 0.32 mg/g of tissue ± 0.033 vs 0.260 mg/g ± 0.030 and 5-FU: 0.660 mg/g ± 0.060 vs 0.52 mg/g ± 0.050, P < .05). CONCLUSION: The use of intrabiliary MR imaging heating guidewire-mediated RF hyperthermia can enhance the chemotherapeutic effect on a human cholangiocarcinoma cell line and local drug deposition in swine CBD tissues.

Current update on combined hepatocellular-cholangiocarcinoma.

Combined hepatocellular-cholangiocarcinoma is a rare but unique primary hepatic tumor with characteristic histology and tumor biology. Recent development in genetics and molecular biology support the fact that combined hepatocellular-cholangiocarcinoma is closely linked with cholangiocarcinoma, rather than hepatocellular carcinoma. Combined hepatocellular cholangiocarcinoma tends to present with an more aggressive behavior and a poorer prognosis than either hepatocellular carcinoma or cholangiocarcinoma. An accurate preoperative diagnosis and aggressive treatment planning can play crucial roles in appropriate patient management.

Multiple liver abscess formation and primary gastrointestinal stromal tumor.

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract. The introduction of a number of small molecule tyrosine kinase inhibitors has revolutionized the management of metastatic disease. Surgery is the mainstay of management for localized disease. Patients with high risk tumors are treated with adjuvant imatinib. We report the rare presentation of a localized primary small bowel gastrointestinal stromal tumor in association with multiple liver abscesses. Cystic liver lesions should be fully evaluated in gastro intestinal tumor patients to exclude an infective cause. Treatment with intravenous antibiotics resulted in clinical and radiological improvement of the liver abscesses. The small bowel tumor was treated with surgical resection.

Cysts of the lower male genitourinary tract: embryologic and anatomic considerations and differential diagnosis.

Cysts of the lower male genitourinary tract are uncommon and usually benign. These cysts have different anatomic origins and may be associated with a variety of genitourinary abnormalities and symptoms. Various complications may be associated with these cysts, such as urinary tract infection, pain, postvoiding incontinence, recurrent epididymitis, prostatitis, and hematospermia, and they may cause infertility. Understanding the embryologic development and normal anatomy of the lower male genitourinary tract can be helpful in evaluating these cysts and in tailoring an approach for developing a differential diagnosis. There are two main groups of cysts of the lower male genitourinary tract: intraprostatic cysts and extraprostatic cysts. Intraprostatic cysts can be further classified into median cysts (prostatic utricle cysts, müllerian duct cysts), paramedian cysts (ejaculatory duct cysts), and lateral cysts (prostatic retention cysts, cystic degeneration of benign prostatic hypertrophy, cysts associated with tumors, prostatic abscess). Extraprostatic cysts include cysts of the seminal vesicle, vas deferens, and Cowper duct. A variety of pathologic conditions can mimic these types of cysts, including ureterocele, defect resulting from transurethral resection of the prostate gland, bladder diverticulum, and hydroureter and ectopic insertion of ureter. Accurate diagnosis depends mainly on the anatomic location of the cyst. Magnetic resonance imaging and transrectal ultrasonography (US) are excellent for detecting and characterizing the nature and exact anatomic origin of these cysts. In addition, transrectal US can play an important therapeutic role in the management of cyst drainage and aspiration, as in cases of prostatic abscess.

Model-based iterative reconstruction versus adaptive statistical iterative reconstruction and filtered back projection in liver 64-MDCT: focal lesion detection, lesion conspicuity, and image noise.

OBJECTIVE: The purpose of this study is to compare three CT image reconstruction algorithms for liver lesion detection and appearance, subjective lesion conspicuity, and measured noise. MATERIALS AND METHODS: Thirty-six patients with known liver lesions were scanned with a routine clinical three-phase CT protocol using a weight-based noise index of 30 or 36. Image data from each phase were reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR). Randomized images were presented to two independent blinded reviewers to detect and categorize the appearance of lesions and to score lesion conspicuity. Lesion size, lesion density (in Hounsfield units), adjacent liver density (in Hounsfield units), and image noise were measured. Two different unblinded truth readers established the number, appearance, and location of lesions. RESULTS: Fifty-one focal lesions were detected by truth readers. For blinded reviewers compared with truth readers, there was no difference for lesion detection among the reconstruction algorithms. Lesion appearance was statistically the same among the three reconstructions. Although one reviewer scored lesions as being more conspicuous with MBIR, the other scored them the same. There was significantly less background noise in air with MBIR (mean [± SD], 2.1 ± 1.4 HU) than with ASIR (8.9 ± 1.9 HU; p < 0.001) or FBP (10.6 ± 2.6 HU; p < 0.001). Mean lesion contrast-to-noise ratio was statistically significantly higher for MBIR (34.4 ± 29.1) than for ASIR (6.5 ± 4.9; p < 0.001) or FBP (6.3 ± 6.0; p < 0.001). CONCLUSION: In routine-dose clinical CT of the liver, MBIR resulted in comparable lesion detection, lesion characterization, and subjective lesion conspicuity, but significantly lower background noise and higher contrast-to-noise ratio compared with ASIR or FBP. This finding suggests that further investigation of the use of MBIR to enable dose reduction in liver CT is warranted.

Liver and heart MR relaxometry in iron loading: reproducibility of three methods.

PURPOSE: To compare the derived T2* values and reproducibility of three methods used to assess iron-loading in heart and liver. MATERIALS AND METHODS: In 23 pediatric patients, liver and cardiac gradient-echo imaging datasets (within-exam repeated sequence pairs) were evaluated. Data analyses compared derived relaxation values (average of pairs) and coefficient of variation (reproducibility of pairs). RESULTS: T2* values showed differences across methods, with pixel-wise mean > average fit > pixel-wise median. Coefficient of variation was found to be lower (better) with pixel-wise median and average fit methods compared to the pixel-wise mean technique. Maximum coefficient of variation values were lowest for the pixel-wise median approach in both the heart and liver. CONCLUSION: Differences in derived T2* values between methods must be considered when comparing values to established magnetic resonance imaging (MRI)-biopsy formulas. The pixel-wise median and average fit methods demonstrate substantial benefits in reproducibility compared to the pixel-wise mean method. Since minimal variation in measurement is critical for patient care, median processing of relaxometry data may be preferable in both tissue types.