Phantom and cadaver measurements of dose and dose distribution in micro-CT of the chest in mice.

BACKGROUND: Micro-computed tomography (CT) allows high-resolution imaging of the chest in mice for small animal research with a significant radiation dose applied. PURPOSE: To report on measurement of the applied radiation dose using different scan protocols in micro-CT of the chest in mice. MATERIAL AND METHODS: Repetitive dose measurements were performed for four different micro-CT protocols (with/without respiratory gating) and for micro-CT fluoroscopy used for chest imaging. Measurements were carried out using thermoluminescence dosimeters (TLD) in mouse cadavers and in a PMMA phantom allowing measurement of the radiation dose in the direct path of rays and assessment of scattered radiation. RESULTS: The dose measured inside and outside the chests of the cadavers varied between 190 und 210 mGy, respectively. The expected mean doses in mice in the direct path of rays for the four examined micro-CT protocols varied between 170 and 280 mGy. The mean values for 1 and 5 minutes of fluoroscopy were 17 mGy and 105 mGy, respectively. CONCLUSION: The measured dose values are similar to the dose values for micro-CT of the chest reported so far. A relevant dose can be delivered by micro-CT of the chest, which could possibly interact with small animal studies. Therefore, the applied dose for a specific protocol should be known and adverse radiation effects be considered.

Respiratory-triggered three-dimensional T2-weighted MR cholangiography after injection of gadoxetate disodium: is it still reliable?

PURPOSE: To test the null hypothesis that there is no quantitative or qualitative difference between respiratory-triggered three-dimensional (3D) T2-weighted magnetic resonance (MR) cholangiography performed before or after administration of gadoxetate disodium. MATERIALS AND METHODS: For this retrospective HIPAA-compliant dual-center study, institutional review board approval was obtained, and a waiver of informed consent was granted. Between July and December 2008, 60 patients (age range, 18-82 years) who were referred for liver MR imaging with gadoxetate disodium underwent respiratory-triggered 3D MR cholangiography before and immediately after completion of portal venous phase contrast material-enhanced T1-weighted MR imaging. Quantitative signal-to-noise ratio (SNR) measurements were obtained in the extrahepatic biliary tract in both MR cholangiographic data sets in each patient. Qualitative assessment was performed by four readers with a four-point scale to assess the depiction of extra- and intrahepatic ducts up to the third order. Statistical analysis consisted of a one-sided Wilcoxon signed rank test, with a P value of less than .05 indicating a significant difference. RESULTS: There was a significant decrease in mean SNR in the MR cholangiographic data set after injection of gadoxetate disodium. SNR was 96 + or - 50 [standard deviation] and 78 + or - 47 before and after contrast media administration, respectively (P < .0001). For all readers, qualitative differences were most obvious in the depiction of the common bile duct and second- and third-order biliary branches, with the precontrast MR cholangiographic data sets being preferred (P < .0001). Precontrast data sets were also significantly preferred in the assessment of the right and left hepatic ducts by all readers. CONCLUSION: Gadoxetate disodium adversely affects respiratory-triggered 3D MR cholangiography, both qualitatively and quantitatively. We recommend that such a sequence be performed before injection of gadoxetate disodium.

Micro-computed tomography of pulmonary fibrosis in mice induced by adenoviral gene transfer of biologically active transforming growth factor-ß1.

BACKGROUND: Micro-computed tomography (micro-CT) is a novel tool for monitoring acute and chronic disease states in small laboratory animals. Its value for assessing progressive lung fibrosis in mice has not been reported so far. Here we examined the importance of in vivo micro-CT as non-invasive tool to assess progression of pulmonary fibrosis in mice over time. METHODS: Pulmonary fibrosis was induced in mice by intratracheal delivery of an adenoviral gene vector encoding biologically active TGF-ß1 (AdTGF-ß1). Respiratory gated and ungated micro-CT scans were performed at 1, 2, 3, and 4 weeks post pulmonary adenoviral gene or control vector delivery, and were then correlated with respective histopathology-based Ashcroft scoring of pulmonary fibrosis in mice. Visual assessment of image quality and consolidation was performed by 3 observers and a semi-automated quantification algorithm was applied to quantify aerated pulmonary volume as an inverse surrogate marker for pulmonary fibrosis. RESULTS: We found a significant correlation between classical Ashcroft scoring and micro-CT assessment using both visual assessment and the semi-automated quantification algorithm. Pulmonary fibrosis could be clearly detected in micro-CT, image quality values were higher for respiratory gated exams, although differences were not significant. For assessment of fibrosis no significant difference between respiratory gated and ungated exams was observed. CONCLUSIONS: Together, we show that micro-CT is a powerful tool to assess pulmonary fibrosis in mice, using both visual assessment and semi-automated quantification algorithms. These data may be important in view of pre-clinical pharmacologic interventions for the treatment of lung fibrosis in small laboratory animals.

Informatics in radiology: sliding-thin-slab averaging for improved depiction of low-contrast lesions with radiation dose savings at thin-section CT.

Current multidetector computed tomography (CT) scanners allow volumetric data acquisition with thin-section collimations and overlapping section reconstructions. The resultant nearly isotropic data sets help minimize partial-volume averaging effects and are ideal for two- and three-dimensional postprocessing and software-assisted lesion detection and quantification. However, the section thickness, image noise, and radiation dose are closely related, and when one parameter must be altered to suit the clinical setting, the others may be affected. When the clinical purpose demands both high spatial resolution and low image noise (eg, for the detection of hypoattenuating lesions in organs such as the kidneys and liver), the necessary trade-off--an increase in the radiation dose to the patient--may be unacceptable. The application of a sliding-thin-slab averaging algorithm during image postprocessing and review helps overcome this limitation by reconstructing thicker sections with lower noise levels from thin-section data obtained with dose-saving protocols. In principle, a high noise level is acceptable in the initial reconstruction of the CT volume data set. During image review at the workstation, the section thickness can be interactively increased to minimize image noise and improve lesion detectability. The combination of thin-section scanning with thick-section display allows routine volumetric imaging without a general increase in radiation dose or a reduction in the detectability of low-contrast lesions. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.302096007/-/DC1.

Teaching surgery, radiology and anatomy together: the mix enhances motivation and comprehension.

PURPOSE: Preclinical and clinical topics are often separated in medical education. For example, surgery and radiology are often taught much later than anatomy. The aim of this study was to establish and to evaluate an interdisciplinary course combining these closely related subjects to enhance medical comprehension. METHODS: Two tutorials each lasting one term were offered to second year medical students, in which clinical topics were implemented linking anatomy to surgical and radiological knowledge. A questionnaire was used to evaluate the success of this approach. RESULTS: The motivation of the students was above average and the practical work was done accurately. The students confirmed that the course improved anatomical comprehension (>95%) and that the learned matters were relevant for their future (90%). Furthermore, interest in the subjects was higher after the course (>85%). Critical suggestions were to extend the course and to include more topics. CONCLUSIONS: A mix of surgery, radiology and anatomy is a teaching concept, which leads to high acceptance and interest in medical students.

Percutaneous interventions for treating ischemic complications of aortic dissection.

The aim of this study was to evaluate the role of percutaneous interventions in treating ischemia complicating aortic dissection. Forty-five patients with ischemia complicating aortic dissection were treated by balloon fenestration, true lumen stenting, angioplasty, or thrombolysis. Clinical and laboratory examinations were performed before and after intervention, and at the end of follow-up (median 37 months). Eighteen dissections were acute, 9 sub-acute, and 18 chronic. Mesenterohepatic ischemia resolved in 16 of 18 patients; lactate and SGOT values fell from 2.89 to 1.23 mmol/L (p=0.006) and from 165.9 to 59.7 U/L (p=0.034), respectively. In patients with renal ischemia, creatinine levels fell from 360.1 to 196.3 micromol/L (p=0.007) accompanied by a significant reduction in blood pressure. Limb-threatening ischemia resolved in three of four patients; in 21 claudicants, the mean walking distance improved from 272 to 1,283 m (p=0.001). Spinal ischemia resolved completely or partially in six of eight patients. Adjunctive surgical measures were necessary in six patients. Overall 30-day mortality in the 45 patients was 6.7%; all three deaths were in patients with acute dissections (mortality in this subgroup 16.7%). Ischemia complicating aortic dissection can be effectively treated by percutaneous interventions resulting in good early and mid-term outcomes.

Optimization of low-contrast detectability in thin-collimated modern multidetector CT using an interactive sliding-thin-slab averaging algorithm.

OBJECTIVES: To analyze the effects of the sliding-thin-slab averaging algorithm on low-contrast performance in MDCT imaging and to find reasonable parameters for clinical routine work. MATERIALS AND METHODS: A low-contrast phantom simulating hypodense lesions (20 HU object contrast) was scanned with a 16-slice spiral CT scanner using different mAs-settings of 25, 50, 100, and 195 mAs. Other scan parameters were as follows: tube voltage = 120 kVp, slice collimation = 0.625 mm, pitch = 1.375 (high speed), reconstruction interval = 0.5 mm. Images were reconstructed with soft, standard, and bone algorithms, resulting in a total of 12 datasets. A sliding-thin-slab averaging algorithm was applied to these primary datasets, systematically varying the slab thickness between 0.5 and 5.0 mm. The low-contrast performance of the resulting datasets was semi-automatically analyzed using a statistical reader-independent approach: A size-dependent analysis of the image noise within the phantom was used to empirically generate a contrast discrimination function (CDF). The ratio between the actual contrast and the minimum contrast necessary for the detection (as given by the CDF) was calculated for all lesions in each dataset and used to evaluate the low-contrast detectability of the different lesions at increasing slab thickness. The results were compared with the original datasets to calculate the improvement in low-contrast detectability. RESULTS: Using the sliding-thin-slab algorithm, low-contrast performance was increased by a factor between 1.1 and 1.7 when compared with the primary dataset. The improvement of the visibility index at optimal slab thickness when compared with the original slice thickness (0.625 mm) was statistically significant (P < 0.05, Student t test) for the following datasets: 8 mm: all datasets; 6 mm: 25 mAs/soft, 195 mAs/bone, 25 mAs/bone; 5 mm: 25 mAs/soft, 25 mAs/bone. The ideal slab thickness over all datasets was 43% (+/-3%) of the diameter of the lesion to be detected. CONCLUSIONS: The use of an interactive sliding-thin-slab averaging algorithm can be readily applied to optimize low-contrast detectability in thin-collimated CT datasets. As a general rule for daily routine, a slice thickness of approximately 2.5 to 3.0 mm can be regarded as a reasonable preset, resulting in an optimized detectability of lesions with a diameter of 5 mm and above.

Comparison of 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine-enhanced MRI in 471 patients with known or suspected renal lesions: results of a multicenter, single-blind, interindividual, randomized clinical phase III trial.

The purpose of this phase III clinical trial was to compare two different extracellular contrast agents, 1.0 M gadobutrol and 0.5 M gadopentate dimeglumine, for magnetic resonance imaging (MRI) in patients with known or suspected focal renal lesions. Using a multicenter, single-blind, interindividual, randomized study design, both contrast agents were compared in a total of 471 patients regarding their diagnostic accuracy, sensitivity, and specificity to correctly classify focal lesions of the kidney. To test for noninferiority the diagnostic accuracy rates for both contrast agents were compared with CT results based on a blinded reading. The average diagnostic accuracy across the three blinded readers ('average reader') was 83.7% for gadobutrol and 87.3% for gadopentate dimeglumine. The increase in accuracy from precontrast to combined precontrast and postcontrast MRI was 8.0% for gadobutrol and 6.9% for gadopentate dimeglumine. Sensitivity of the average reader was 85.2% for gadobutrol and 88.7% for gadopentate dimeglumine. Specificity of the average reader was 82.1% for gadobutrol and 86.1% for gadopentate dimeglumine. In conclusion, this study documents evidence for the noninferiority of a single i.v. bolus injection of 1.0 M gadobutrol compared with 0.5 M gadopentate dimeglumine in the diagnostic assessment of renal lesions with CE-MRI.

High-resolution 64-slice helical-computer-assisted-tomographical-angiography as a diagnostic tool before CABG surgery: the dawn of a new era?

OBJECTIVE: For the first time, technical developments in helical, high-resolution 64-slice computer-assisted-tomographical-scanning (CT) allows for analysis of cardiac pathology including coronary morphology. Here, we present results of a multicenter study assessing the value CT-angiography as a preoperative diagnostic tool in identifying target vessels for coronary artery bypass grafting (CABG) surgery. METHODS: Thirty-two patients aged 64+/-9.0 years, 30 with confirmed coronary disease (angiography or scintigraphy) and 2 controls, underwent helical CT analysis. Scans were reviewed in a blinded fashion and potential target vessels for CABG were identified by seven individual reviewers. Results were compared with those from conventional coronary angiography and with the target vessels chosen at surgery. RESULTS: Results showed a high positive predictive value for targeting at surgery, which was comparable for both conventional angiography and CT scan (LAD 100% vs 97%, RCx 96% vs 93%, 67% vs 56%). In one patient, who presented with clinical signs of CAD and positive scintigraphy results, conventional angiography revealed no stenotic lesion and CT scan was used to confirm main stem disease. CONCLUSIONS: CT-angiography sufficiently allows for target vessel determination for CABG. In individual cases, visual assessment of the left main coronary artery and the proximal left anterior descending artery (LAD) via CT-angiography may be superior to conventional angiography. However, while there is no difference in positive predictive targeting value, sensitivity and specificity of conventional angiography is still superior. Also, improvements in the methodology of evaluation and presentation of CT-findings are necessary. Our data suggest that CT-angiography may be used as a clinical alternative to conventional angiography in preoperative assessment for cardiac surgery.

Transarterial chemoembolization using degradable starch microspheres and iodized oil in the treatment of advanced hepatocellular carcinoma: evaluation of tumor response, toxicity, and survival.

BACKGROUND: In a multidisciplinary conference patients with advanced non-resectable hepatocellular carcinoma (HCC) were stratified according to their clinical status and tumor extent to different regional modalities or to best supportive care. The present study evaluated all patients who were stratified to repeated transarterial chemoembolization (TACE) from 1999 until 2003 in terms of tumor response, toxicity, and survival. A moderate embolizing approach was chosen using a combination of degradable starch microspheres (DSM) and iodized oil (Lipiodol) in order to combine anti-tumoral efficiency and low toxicity. METHODS: Fourty-seven patients were followed up prospectively. TACE treatment consisted of cisplatin (50 mg/m(2)), doxorubicin (50 mg/m(2)), 450-900 mg DSM, and 5-30 ml Lipiodol. DSM and Lipiodol were administered according to tumor vascularization. Patient characteristics, toxicity, and complications were outlined. In multivariate regression analyses of pre-treatment variables from a prospective database, predictors for tumor response and survival after TACE were determined. RESULTS: 112 TACE courses were performed (2.4+/-1.5 courses per patient). Mean maximum tumor size was 75 (+/-43) mm, in 68% there was bilobar disease. Best response to TACE treatment was: progressive disease (PD) 9%, stable disease (SD) 55%, partial remission (PR) 36%, and complete remission (CR) 0%. Multivariate regression analyses identified tumor size 30 months, R(2)=36%). Grade 3 toxicity occurred in 7.1% (n=8), and grade 4 toxicity in 3.6% (n=4) of all courses in terms of reversible leukopenia and thrombocytopenia. The incidence of major complications was 5.4% (n=6). All complications were managed conservatively. The mortality within 6 weeks after TACE was 2.1% (one patient). CONCLUSIONS: DSM and Lipiodol were combined successfully in the palliative TACE treatment of advanced HCC resulting in high rates of tumor response and survival at limited toxicity. Favourable tumor response was associated with tumor extent and vascularization. TACE using DSM and Lipiodol can be considered a suitable palliative measure in patients who might not tolerate long acting embolizing agents.

Renal metastases from follicular thyroid cancer on SPECT/CT.

In well-differentiated thyroid carcinoma, only a subset of patients develop distant metastases, predominantly to the lungs and the skeletal system. Only a few cases of metastatic spread to the kidneys are described in the literature. We report the case of a 64-year-old woman with a long history of follicular thyroid cancer who developed renal metastases. The lesions were detected with I-131 scintigraphy, SPECT/CT and thin-collimated contrast-enhanced CT. Subsequent surgery and histopathologic analysis of the renal lesions confirmed the diagnosis.

Nonossifying fibroma can mimic residual lymphoma in FDG PET: additional value of combined PET/CT.

A 12-year-old girl was diagnosed with Hodgkin's lymphoma and underwent conventional cross-sectional imaging for initial staging. Chemotherapy was given according to standard pediatric protocols. At the end of therapy, an F-18 FDG PET/CT examination was performed to evaluate the therapeutic response. The scan demonstrated focal uptake of FDG in the right distal femur and residual lymphoma was taken into consideration. However, findings in the coregistered CT scan were consistent with nonossfiying fibroma, a common benign skeletal lesion. Combined PET/CT imaging can be helpful to identify benign bone lesions mimicking metastatic or residual disease in F-18 FDG PET as illustrated by this case.

Combination of repeated single-session percutaneous ethanol injection and transarterial chemoembolisation compared to repeated single-session percutaneous ethanol injection in patients with non-resectable hepatocellular carcinoma.

AIM: To evaluate the treatment effect of percutaneous ethanol injection (PEI) for patients with advanced, non-resectable HCC compared with combination of transarterial chemoembolisation (TACE) and repeated single-session PEI, repeated single-session PEI alone, repeated TACE alone, or best supportive care. METHODS: All patients who received PEI treatment during the study period were included and stratified to one of the following treatment modalities according to physical status and tumor extent: combination of TACE and repeated single-session PEI, repeated single-session PEI alone, repeated TACE alone, or best supportive care. Prognostic value of clinical parameters including Okuda-classification, presence of portal vein thrombosis, presence of ascites, number of tumors, maximum tumor diameter, and serum cholinesterase (CHE), as well as Child-Pugh stage, alpha-fetoprotein (AFP), fever, incidence of complications were assessed and compared between the groups. Survival was determined using Kaplan-Meier and multivariate regression analyses. RESULTS: The 1- and 3-year survival of all patients was 73% and 47%. In the subgroup analyses, the combination of TACE and PEI (1) was associated with a longer survival (1-, 3-, 5-year survival: 90%, 52%, and 43%) compared to PEI treatment alone (2) (1-, 3-, 5-year survival: 65%, 50%, and 37%). Secondary PEI after initial stratification to TACE (3) yielded comparable results (1-, 3-, 5-year survival: 91%, 40%, and 30%) while PEI after stratification to best supportive care (4) was associated with decreased survival (1-, 3-, 5-year survival: 50%, 23%, 12%). Apart from the chosen treatment modalities, predictors for better survival were tumor number (n < 5), tumor size (< 5 cm), no ascites before PEI, and stable serum cholinesterase after PEI (P < 0.05). The mortality within 2 wk after PEI was 2.8% (n = 3). There were 24 (8.9%) major complications after PEI including segmental liver infarction, focal liver necrosis, and liver abscess. All complications could be managed non-surgically. CONCLUSION: Repeated single-session PEI is effective in patients with advanced HCC at an acceptable and manageable complication rate. Patients stratified to a combination of TACE and PEI can expect longer survival than those stratified to repeated PEI alone. Furthermore, patients with large or multiple tumors in good clinical status may also profit from a combination of TACE and reconsideration for secondary PEI.

Initial experience from a combination of systemic and regional chemotherapy in the treatment of patients with nonresectable cholangiocellular carcinoma in the liver.

AIM: In nonresectable cholangiocellular carcinoma (CCC) therapeutic options are limited. Recently, systemic chemotherapy has shown response rates of up to 30%. Additional regional therapy of the arterially hyper vascularized hepatic tumors might represent a rational approach in an attempt to further improve response and palliation. Hence, a protocol combining transarterial chemoembolization and systemic chemotherapy was applied in patients with CCC limited to the liver. METHODS: Eight patients (6 women, 2 men, mean age 62 years) with nonresectable CCC received systemic chemotherapy (gemcitabine 1 000 mg/m(2)) and additional transarterial chemoembolization procedures (50 mg/m(2) cisplatin, 50 mg/m(2) doxorubicin, up to 600 mg degradable starch microspheres). Clinical follow-up of patients, tumor markers, CT and ultrasound were performed to evaluate maximum response and toxicity. RESULTS: Both systemic and regional therapies were tolerated well; no severe toxicity (WHO III/IV) was encountered. Nausea and fever were the most commonly observed side effects. A progressive rarefication of the intrahepatic arteries limited the maximum number of chemoembolization procedures in 4 patients. A median of 2 chemoembolization cycles (range, 1-3) and a median of 6.5 gemcitabine cycles (range, 4-11) were administered. Complete responses were not achieved. As maximum response, partial responses were achieved in 3 cases, stable diseases in 5 cases. Two patients died from progressive disease after 9 and 10 mo. Six patients are still alive. The current median survival is 12 mo (range, 9-18); the median time to tumor progression is 7 mo (range, 3-18). Seven patients suffered from tumor-related symptoms prior to therapy, 3 of these experienced a treatment-related clinical relief. In one patient the tumor became resectable under therapy and was successfully removed after 10 mo. CONCLUSION: The present results indicate that a combination of systemic gemcitabine therapy and repeated regional chemoembolizations is well tolerated and may enhance the effect of palliation in a selected group of patients with intrahepatic nonresectable CCC.

Contrast media nephropathy: intravenous CT angiography versus intraarterial digital subtraction angiography in renal artery stenosis: a prospective randomized trial.

BACKGROUND: Spiral computed tomographic angiography (CTA) is a noninvasive method to diagnose renal artery stenosis (RAS). In digital subtraction angiography (DSA), contrast media (CM) is injected directly into the renal artery; in CTA, a greater amount of CM is injected intravenously, potentially leading to an increased incidence of CM nephropathy. METHODS: We investigated 80 patients with suspected RAS randomized to either CTA or DSA prospectively. The following parameters were determined: serum creatinine level and single-shot inulin clearance for evaluation of renal function and urine alpha1-microglobulin and beta-N-acetyl-glucoseaminidase (beta-NAG) as markers for tubular toxicity. Data from 16 patients undergoing angioplasty in the same session were excluded. RESULTS: In the CTA and DSA groups, 163 +/- 13 and 104 +/- 56 mL of CM (mean +/- SD; P < 0.0001) were administered, respectively. Mean serum creatinine levels increased from 1.78 +/- 1.61 to 1.92 +/-1.73 mg/dL (157 +/- 142 to 170 +/- 153 micromol/L; P = 0.00001) in the CTA group and from 1.52 +/- 1.23 to 1.60 +/- 1.28 mg/dL (134 +/- 109 to 141 +/- 113 micromol/L; P = 0.01) in the DSA group. Mean inulin clearance decreased from 63 +/- 28 to 58 +/- 23 mL/min (P = 0.01) and 65 +/- 26 to 62 +/- 26 mL/min (P < 0.01), median beta-NAG levels increased from 4.6 to 6.0 U/g creatinine (P = not significant) and 2.5 to 8.0 U/g creatinine (P < 0.001), and median alpha1-microglobulin levels increased from 13 to 17 microg/g creatinine (P < 0.025) and 11 to 21 microg/g creatinine (P = not significant) in the CTA and DSA groups, respectively. CM nephropathy occurred in 3 of 33 patients in the CTA group and 2 of 31 patients in the DSA group. The increase in creatinine level was reversible in all patients within 7 days. CONCLUSION: On this study, CTA performed for the detection of RAS is not associated with an increased risk for CM nephropathy compared with intraarterial DSA despite a greater dose of CM.

Diameters of the thoracic aorta throughout life as measured with helical computed tomography.

OBJECTIVE: The use of helical computed tomography is well established in the evaluation of the thoracic aorta. Nevertheless, normal diameters and their changes during adult life according to this method are not available. We planned to set up normal diameters for the thoracic aorta of adults obtained by helical computed tomography. METHODS: Seventy adults, 17 to 89 years old, without any signs of cardiovascular disease were investigated with helical computed tomography. Aortic diameters were measured at seven predefined thoracic levels. RESULTS: Aortic diameters (mean +/- SD) were 2.98 +/- 0.46 cm at the aortic valve sinus, 3.09 +/- 0.41 cm at the ascending aorta, 2.94 +/- 0.42 cm proximal to the innominate artery, 2.77 +/- 0.37 cm at the proximal transverse arch, 2.61 +/- 0.41 cm at the distal transverse arch, 2.47 +/- 0.40 cm at the isthmus, and 2.43 +/- 0.35 cm at the diaphragm. Men had slightly longer diameters than did women. All diameters increased with age. There was no influence of weight, height, or body surface area. After normalization to the diameter at diaphragmatic level, no statistically significantly influential factor could be detected. CONCLUSIONS: This study delineates normal intrathoracic aortic diameters for helical computed tomography, including relationships with sex and age. Pathologic dimensions of the aorta should preferably be provided as percentiles or z scores.

Assessment of sequential enhancement patterns of focal nodular hyperplasia and hepatocellular carcinoma on mangafodipir trisodium enhanced MR imaging.

RATIONALE AND OBJECTIVES: Sequential contrast changes of mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance imaging (MRI) were evaluated in the differentiation of focal nodular hyperplasias (FNH) and hepatocellular carcinomas (HCC). METHODS: Patients with FNH (n = 16) or HCC (n = 12) underwent MRI: T2-weighted fast spin echo before and T1-weighted gradient echo before and 1, 4, 14, and 22 hours after 5 micromol/kg Mn-DPDP. Homogeneity of enhancement and delineation of fibrous scars of FNHs were assessed qualitatively. Lesion-to-liver contrast changes of FNHs and HCCs were compared quantitatively (Mann-Whitney U). RESULTS: Mn-DPDP improved detection of characteristic scars of FNHs from 50% before to 90% after contrast agent. Apart from fibrous tissue enhancement of FNHs was mostly homogeneous (90%). Time-dependent contrast changes were up to 20 times higher (after 4 hours) for FNHs than HCCs (P < 0.0001). CONCLUSIONS: Mn-DPDP-enhanced MRI helps to delineate characteristic morphologic features of FNHs and can provide quantitative data differentiating FNH and HCC.

Transcutaneous perianal sonography: a sensitive method for the detection of perianal inflammatory lesions in Crohn's disease.

AIM: Pelvic magnetic resonance imaging (MRI) and endoanal ultrasound which are established imaging methods for perianal inflammatory lesions in patients with Crohn's disease require expensive specialized equipments and expertise. We investigated the feasibility and sensitivity of transcutaneous perianal ultrasound (PAUS) using regular ultrasound probes in the imaging of perianal inflammatory lesions. The sonographic findings were correlated to pelvic MRI-scans. METHODS: We performed PAUS in 25 patients with Crohn's disease and clinical signs of perianal inflammatory disease. Within a median of 10 d (range 0-75) these patients underwent MRI of the pelvis. Regular convex and linear high resolution probes were used for PAUS. The sonographic findings were correlated to the MRI findings by blinded investigators. RESULTS: The sonographic investigations were well tolerated by all patients. Fistulae typically presented as hypoechoic tracks. Twenty-nine fistulae were detected in 22 patients. Abscesses were detected in 7 patients and presented as hypo- or anechoic formations. Twenty-six of 29 fistulae and 6 of 7 abscesses could be confirmed by MRI. Kappa statistics showed an excellent agreement (kappa>0.83) between the two imaging methods. CONCLUSION: PAUS is a simple, painless, feasible, real-time method that can be performed without specific patient preparation which is comparable in its sensitivity to pelvic MRI in the detection of perianal fistulae and/or abscesses. PAUS can especially be recommended as a screening tool in acute perianal disorders such as perianal abscess and for follow-up studies of perianal inflammatory disease.

PET/CT imaging of c-Myc transgenic mice identifies the genotoxic N-nitroso-diethylamine as carcinogen in a short-term cancer bioassay.

BACKGROUND: More than 100,000 chemicals are in use but have not been tested for their safety. To overcome limitations in the cancer bioassay several alternative testing strategies are explored. The inability to monitor non-invasively onset and progression of disease limits, however, the value of current testing strategies. Here, we report the application of in vivo imaging to a c-Myc transgenic mouse model of liver cancer for the development of a short-term cancer bioassay. METHODOLOGY/PRINCIPAL FINDINGS: µCT and ¹8F-FDG µPET were used to detect and quantify tumor lesions after treatment with the genotoxic carcinogen NDEA, the tumor promoting agent BHT or the hepatotoxin paracetamol. Tumor growth was investigated between the ages of 4 to 8.5 months and contrast-enhanced µCT imaging detected liver lesions as well as metastatic spread with high sensitivity and accuracy as confirmed by histopathology. Significant differences in the onset of tumor growth, tumor load and glucose metabolism were observed when the NDEA treatment group was compared with any of the other treatment groups. NDEA treatment of c-Myc transgenic mice significantly accelerated tumor growth and caused metastatic spread of HCC in to lung but this treatment also induced primary lung cancer growth. In contrast, BHT and paracetamol did not promote hepatocarcinogenesis. CONCLUSIONS/SIGNIFICANCE: The present study evidences the accuracy of in vivo imaging in defining tumor growth, tumor load, lesion number and metastatic spread. Consequently, the application of in vivo imaging techniques to transgenic animal models may possibly enable short-term cancer bioassays to significantly improve hazard identification and follow-up examinations of different organs by non-invasive methods.