[Modern interdisciplinary management of a uretero-iliac artery fistula (case report)]. / Modernes interdisziplinäres Management einer uretero-iliakalen Fistel (Fallbericht).

INTRODUCTION: Abnormal links between the arterial system and other luminal systems are a challenge to those in charge of their adequate diagnostic and therapeutic management. OBJECTIVE: Scientific case report on an individual who underwent successful treatment combining vascular-surgical and interventional radiology techniques for a rare right uretero-iliac artery fistula based on personal clinical experience, a selective literature research and a detailed discussion of current recommendations for diagnostic workup and subsequent treatment. CASE CHARACTERISTICS: A 79-year-old patient was admitted with haematuria : and bladder tamponade : in the presence of bilateral actinic ureteral strictures secondary to neoadjuvant radiochemotherapy followed by abdominoperineal rectum exstirpation due to suprasphincteric rectal cancer (ypT3ypN0M0). Laboratory tests revealed anaemia; transabdominal ultrasound demonstrated bilateral urinary retention. A complementary CT scan did not reveal any manifest bleeding resulting from intermittent haemorrhage. SURGICAL PROCEDURE: Initially, the bladder haematoma was removed and ureteral catheters were changed. Due to endoluminal bleeding in the right ureter, a combined procedure was initiated, involving a vascular-surgical approach (access to the right femoral artery, ultimate disobliteration and intimal refixation in the right superficial femoral artery due to dissection) and an interventional radiology approach (insertion of an Amplatzer [AMPLATZER™Vascular Plug II; St. Jude Medical, Saint Paul, Minnesota, USA] into the right internal iliac artery and iliac stenting by a cross-over manoeuvre from the left femoral access site) although no acute bleeding was detected in the CT scan (but acute haemorrhage from the right ureteric ostium was confirmed during cystoscopy). CLINICAL COURSE: The patient stabilised in due time in response to periinterventional treatment in the ICU. He was discharged on the 15th day after surgery without evidence of recurrent haemorrhage. SUMMARY: In the presented case, this promptly initiated (vascular-surgical and interventional radiology) hybrid operation was absolutely indicated, being the approach with the best prospects for recurrent arterial bleeding with clinical manifestation of haematuria and haemorrhage within the urinary bladder due to a uretero-iliac artery fistula. CONCLUSION: Today, a minimally invasive approach with stenting is the method of choice in the sequential, urgent management of a potentially life-threatening uretero-iliac fistula in the presence of arterial endoluminal bleeding and an imminent haemorrhagic shock.

Upper-Urinary-Tract Effects After Irreversible Electroporation (IRE) of Human Localised Renal-Cell Carcinoma (RCC) in the IRENE Pilot Phase 2a Ablate-and-Resect Study.

PURPOSE: Irreversible electroporation (IRE) is a new potential ablation modality for small renal masses. Animal experiments have shown preservation of the urine-collecting system (UCS). The purpose of this clinical study was to perform the first evaluation and comparison of IRE's effects on the renal UCS by using urinary cytology, magnetic-resonance imaging, and resection histology in men after IRE of pT1a renal-cell carcinoma (RCC). METHODS: Seven patients with biopsy-proven RCC pT1a cN0cM0 underwent IRE in a phase 2a pilot ablate-and-resect study (IRENE trial). A contrast-enhanced, diffusion-weighted MRI and urinary cytology was performed 1 day before and 2, 7, and 27 days after IRE. Twenty-eight days after IRE the tumour region was completely resected surgically. RESULTS: Technical feasibility was demonstrated in all patients. In all cases, MRI revealed complete coverage of the tumour area by the ablation zone with degenerative change. The urographic late venous MRI phase (urogram scans) demonstrated normal morphological appearances. Urine cytology showed a temporary vacuolisation of the cyto- and caryoplasmas after IRE. Whereas the urothelium showed signs of regeneration 28 days after IRE-ablation, the tumour and parenchyma below it showed necrosis and permanent tissue destruction. CONCLUSIONS: Renal percutaneous IRE appears to be a safe treatment for pT1a RCC. The preservation of the UCS with unaltered normal morphology as well as urothelial regeneration and a phenomenon (new in urinary cytology) of temporary degeneration with vacuolisation of detached transitional epithelium cells were demonstrated in this clinical pilot study.

[Recurrent pain and swelling of the left leg in a 49-year-old male patient]. / Rezidivierende Beinschwellungen und Schmerzen im linken Bein bei einem 49-jährigen Patienten.

A 49-year-old male patient presented due to recurrent pain and swelling in the left leg. The patient had had deep venous thrombosis with pulmonary embolism 5 years previously. Since then, he had been treated with Vit-k-antagonists. Pronounced paraumbilical collateral circulation of unknown origin was striking. Doppler sonographic evaluation pointed to May-Thurner syndrome. This was confirmed by phlebography. Venous stenting of the stenosis in the left iliac vein achieved long-term symptom improvement. This case report is intended to draw attention to the rare May-Thurner syndrome as an important differential diagnosis of deep vein thrombosis and, at the same time, identify diagnostic and therapeutic treatment strategies.

[Prostate gland - what would urologists like to know from radiologists?] / Die Vorsteherdrüse ­ was möchte der Urologe vom Radiologen wissen?

A more than 100-year period, where the prostate was only seen and treated as a whole is coming to an end right now. Finally, high resolution imaging is providing deep insights and detailed information so that new therapeutic procedures can aim for the smallest targets within the gland. The long-standing wish of patients for individual noninvasive diagnostics and treatment of prostate diseases can now be fulfilled by providing new tailored concepts; however, in order to transfer the enormous amount of new information into the specific clinical patient situation, a closely knit interdisciplinary approach is required. In this setting, the traditional outpatient consultation service is overstretched in every aspect. It is now the time for new innovative constructs. The current one-sided service concept for urologists, radiologists and radiation therapists is therefore behind the times and the development of a "prostate management team" with equally cooperating partners from each specialty is the task for the future.

A prospective Phase 2a pilot study investigating focal percutaneous irreversible electroporation (IRE) ablation by NanoKnife in patients with localised renal cell carcinoma (RCC) with delayed interval tumour resection (IRENE trial).

INTRODUCTION: Focal ablation therapy is playing an increasing role in oncology and may reduce the toxicity of current surgical treatments while achieving adequate oncological benefit. Irreversible electroporation (IRE) has been proposed to be tissue-selective with potential advantages compared with current thermal-ablation technologies or radiotherapy. The aim of this pilot trial is to determine the effectiveness and feasibility of focal percutaneous IRE in patients with localised renal cell cancer as a uro-oncological tumour model. METHODS: Prospective, monocentric Phase 2a pilot study following current recommendations, including those of the International Working Group on Image-Guided Tumor Ablation. Twenty patients with kidney tumour (T1aN0M0) will be recruited. This sample permits an appropriate evaluation of the feasibility and effectiveness of image-guided percutaneous IRE ablation of locally confined kidney tumours as well as functional outcomes. Percutaneous biopsy for histopathology will be performed before IRE, with magnetic-resonance imaging one day before and 2, 7, 27 and 112 days after IRE; at 28 days after IRE the tumour region will be completely resected and analysed by ultra-thin-layer histology. DISCUSSION: The IRENE study will investigate over a short-term observation period (by magnetic-resonance imaging, post-resection histology and assessment of technical feasibility) whether focal IRE, as a new ablation procedure for soft tissue, is feasible as a percutaneous, tissue-sparing method for complete ablation and cure of localised kidney tumours. Results from the kidney-tumour model can provide guidance for designing an effectiveness and feasibility trial to assess this new ablative technology, particularly in uro-oncology.

[Percutaneous interventions in an open MR system: technical background and clinical indications]. / Perkutane Interventionen in einem offenen MR-System: Technischer Hintergrund und klinische Indikationen.

The latest and therefore more efficient open magnetic resonance (MR) scanners with a field strength of 1 T allow freehand fluoroscopic interventions with excellent image quality. Specifically designed interactive software simplifies examination planning and performance. Guidance in two imaging planes allows fast and accurate device positioning and interventional procedures during free breathing. The diagnostic and therapeutic spectrum includes a wide variety of interstitial percutaneous interventions. The most important are periradicular therapy (PRT), intra-abdominal drainage and nephrostoma placement, biopsies, especially in the breasts and liver and focal ablation therapy of malignant hepatic or renal lesions. As the approach is fast and robotic devices are not needed the method is increasingly being carried out in the clinical routine. A drawback of MR-guided interventions is the limitation in verbal communication during image acquisition. Furthermore, the portfolio of MR compatible instruments needs to be extended.

Short- and mid-term effects of irreversible electroporation on normal renal tissue: an animal model.

PURPOSE: Irreversible electroporation (IRE) is a novel nonthermal tissue ablation technique by high current application leading to apoptosis without affecting extracellular matrix. Previous results of renal IRE shall be supplemented by functional MRI and differentiated histological analysis of renal parenchyma in a chronic treatment setting. METHODS: Three swine were treated with two to three multifocal percutaneous IRE of the right kidney. MRI was performed before, 30 min (immediate-term), 7 days (short-term), and 28 days (mid-term) after IRE. A statistical analysis of the lesion surrounded renal parenchyma intensities was made to analyze functional differences depending on renal part, side and posttreatment time. Histological follow-up of cortex and medulla was performed after 28 days. RESULTS: A total of eight ablations were created. MRI showed no collateral damage of surrounded tissue. The highest visual contrast between lesions and normal parenchyma was obtained by T2-HR-SPIR-TSE-w sequence of DCE-MRI. Ablation zones showed inhomogeneous necroses with small perifocal edema in the short-term and sharp delimitable scars in the mid-term. MRI showed no significant differences between adjoined renal parenchyma around ablations and parenchyma of untreated kidney. Histological analysis demonstrated complete destruction of cortical glomeruli and tubules, while collecting ducts, renal calyxes, and pelvis of medulla were preserved. Adjoined kidney parenchyma around IRE lesions showed no qualitative differences to normal parenchyma of untreated kidney. CONCLUSIONS: This porcine IRE study reveals a multifocal renal ablation, while protecting surrounded renal parenchyma and collecting system over a mid-term period. That offers prevention of renal function ablating centrally located or multifocal renal masses.

[Irreversible electroporation: the new generation of local ablation techniques for renal cell carcinoma]. / Irreversible Elektroporation : Die neue Generation lokaler Ablationsverfahren beim Nierenzellkarzinom.

BACKGROUND: Local ablation techniques are a major focus of current developments in oncology. The primary aim is to retain organs and preserve organ functions without compromising the oncological outcome. METHOD: Irreversible electroporation (IRE) is a novel ablation technique that involves the application of high-voltage pulses to induce cell apoptosis without causing thermal damage to the target tissue or adjacent structures. AIM: First published in 2005 IRE is currently undergoing preclinical and clinical trials in several areas of oncology and the initial results have been promising. The IRE technique could be a significant development in ablation treatment for renal cell carcinoma (RCC) but decisive proof of its effectiveness for local RCC has not yet been provided. This study presents the results of preclinical and initial clinical trials which are discussed and compared with those of other ablation techniques in order to demonstrate the current value of IRE.

[Placement of percutaneous nephrostomy by open magnetic resonance imaging: clinical results and current status in urology]. / Einlage einer perkutanen Nephrostomie im offenen Magnetresonanztomographen : Klinische Ergebnisse und aktueller Status in der Urologie.

BACKGROUND: Percutaneous nephrostomy (PCN) tube placement under combined ultrasound and fluoroscopic guidance is a standard procedure in urology. The use of a 1 Tesla open magnetic resonance imaging (MRI) scanner enables PCN placement under real-time guidance. METHOD: In the present series 51 patients underwent a total of 79 MRI-guided procedures between 2008 and 2012 and 52 interventions were performed after failure of conventional urological manipulation. Of the procedures 55 involved only a minor urine transport disorder (UTD) or none at all. RESULTS: Puncture and subsequent PCN tube placement were successful in all patients. Extravasation was found in four patients and renal pelvic clots in three. All complications healed without sequelae or further interventions. CONCLUSION: The MRI-guided PCN tube placement is an optimal alternative, particularly in cases of limited conventional imaging.

MRI versus bone scintigraphy. Evaluation for diagnosis and grading of stress injuries.

AIM: This study was set up to determine the value of magnetic resonance imaging (MRI) and bone scintigraphy (BS) for the diagnosis of stress injuries in athletes, and furthermore to assess reliability and prediction of healing time. PATIENTS, METHODS: Imaging data was analyzed retrospectively from 28 athletes who had received MRI and BS examinations for suspected stress injuries. MRI- and BS-data were rated by three specialists each in a blinded read, using a 5-point score (i.e. 0-4: inconspicuous to high-grade stress fracture). An interdisciplinary expert truth-panel set the reference standard. Standard statistical parameters, Fleiss' kappa (κ), and group comparisons were calculated. RESULTS: The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for detection of stress injuries were 71.4%, 85.7%, 78.6%, 83.3% and, 75.0%, for MRI and 92.9%, 73.8%, 83.3%, 78.0% and, 91.2% for BS, respectively. Interobserver reliability for the diagnosis of a stress injury was κ = 0.9 for BS and κ = 0.85 for MRI. Mean healing times of mild (grades 1 and 2) and severe (grades 3 and 4) stress injuries were 88 days (d) versus 142d for BS and 57d versus 116d for MRI. No significant difference in healing time could be shown. CONCLUSIONS: MRI and BS reliably detect stress injuries. MRI is to be recommended as the primary imaging modality due to its potential for assessment of differential diagnoses and the lack of radiation exposure, the value of BS lies in the exclusion of stress fractures after inconclusive MRI examinations.

Detection and characterisation of focal liver lesions in colorectal carcinoma patients: comparison of diffusion-weighted and Gd-EOB-DTPA enhanced MR imaging.

OBJECTIVE: To compare diffusion-weighted imaging (DWI) and Gd-EOB-DTPA-enhanced magnetic resonance (MR) imaging for the detection and characterisation of focal liver lesions (FLLs) in patients with colorectal carcinoma. METHODS: Seventy-three patients underwent MR imaging including echoplanar DWI (MR-DWI) and dynamic (MR-Dyn) and hepatobiliary phase (MR-Late) Gd-EOB-DTPA-enhanced images. Two blinded readers independently reviewed 5 different image sets using a 5-point confidence scale. Accuracy was assessed by the area (A(z)) under the receiver operating characteristic curve, and sensitivity and specificity were calculated. RESULTS: A total of 332 FLLs were evaluated. Detection rates were significantly higher for MR-Late images (94.4% for benign and 100% for malignant lesions) compared with MR-DWI (78.3% and 97.5%) and MR-Dyn images (81.5% and 89.9%). Accuracy was 0.82, 0.76 and 0.89 for MR-DWI, MR-Dyn and MR-Late images while sensitivity was 0.98, 0.87 and 0.95, respectively. For characterisation of subcentimetre lesions sensitivity was highest for MR-DWI (0.92). Combined reading of unenhanced and contrast-enhanced images had an identical high accuracy of 0.98. CONCLUSION: Late-phase Gd-EOB-DTPA-enhanced images were superior for the detection of FLLs, while DWIs were most valuable for the identification of particularly small metastases. Combined interpretation of unenhanced images resulted in precise characterisation of FLLs.

[Splenic granulomas - rare extraintestinal manifestation of Crohn's disease]. / Milzbefall - seltene extraintestinale Manifestation bei Morbus Crohn.

Extraintestinal manifestations of inflammatory bowel disease occur frequently in parallel to the inflammation in the bowel. The activity of extraintestinal manifestations is often divergent to the activity of intestinal inflammation. We here present the case of a rare extraintestinal manifestation of Crohn's disease and report on a 52-year-old patient with known Crohn's disease and primary sclerosing cholangitis (PSC) in clinical remission. Multiple lesions of the spleen were observed in routine MR tomography. The histological examination of a specimen obtained by MR-guided fine needle biopsy showed non-caseating epitheloid cell granulomas. The splenic granulomas regressed completely and spontaneously without specific immunmodulatory therapy.

Osteochondral defect repair after implantation of biodegradable scaffolds: indirect magnetic resonance arthrography and histopathologic correlation.

BACKGROUND: Biodegradable scaffolds have become an important option in the treatment of osteochondral defects. Therefore, accurate and reproducible monitoring of scaffold repair tissue is crucial. PURPOSE: To assess the feasibility of indirect magnetic resonance (MR) arthrography in determining the quality of osteochondral repair after scaffold implantation using an MR imaging (MRI) scoring and grading system with histology as reference. MATERIAL AND METHODS: Osteochondral defects created at ovine condylar facets were treated with either a commercial poly (DL-lactide-co-glycolide) (PLG) scaffold or a modified softer one (n=6/group; 87% and 55% of the elastic modulus of ovine subchondral bone, respectively). Empty defects at the contralateral condyle served as control group. A 1.5T MRI scan was performed after 6 months with proton density (PD)-weighted (w) fat-saturated (fs) fast spin-echo (FSE), T1-w two-dimensional (2D), and 3D fs gradient echo (GE) sequences 30 min after intravenous Gd-DTPA administration and passive joint movement. Two independent radiologists evaluated the repair tissue. The MR findings were correlated with histological findings. RESULTS: MRI and histological grading correlated well (10/12 cases). The stiff-scaffold group showed significantly superior repair in comparison to the control group (P<0.05). The 3D fs GE sequence proved to be most valuable in evaluating morphologic status. Complete defect filling and integration, intact surface and isointense signal to the adjacent native cartilage, subchondral incorporation with bone marrow edema, and graft plug enhancement were associated with a good histological outcome. Histologically, we found a smooth fibrocartilaginous layer and osseous replacement of the scaffold. Incomplete cartilage repair and irregular subchondral structures on the MRI correlated histologically with fibrocartilage-like repair and subchondral sclerosis, due to substantial degradation of the scaffold. CONCLUSION: Indirect MR arthrography is an accurate, noninvasive monitoring tool in the follow-up of scaffold implants. The MRI scoring and grading system allows reliable assessment of normal and pathological repair, with high correlation to histological findings.

Quantitative proton magnetic resonance spectroscopy of the normal liver and malignant hepatic lesions at 3.0 Tesla.

This comparative study of tumour patients and volunteers aimed at differentiating liver parenchyma from neoplastic lesions by using localised (1)H MRS at 3.0 T as an adjunct to MRI. In total 186 single-voxel proton spectra of the liver were acquired at 3.0 T using the body transmit receive coil. Consecutive stacks of breath-hold spectra were acquired in the PRESS technique at a short echo time of 35 ms and a repetition time of 2,000 ms. Processing of the spectra included spectral alignment with the software package SAGE and quantitative processing with LCModel. The resulting metabolite concentrations were presented in arbitrary units relative to the internal water. In general, the spectra showed four main groups of resonances originating from the methyl protons (0.8-1.1 ppm) and methylene protons of the lipids (1.1-1.5 ppm; 2.0-2.2 ppm) as well as the methyl protons of choline-containing compounds (CCC) at 3.2 ppm. Overall, the CCC and lipid values in malignant liver tumours showed no significant differences to liver parenchyma. On average, total lipid measurements in normal liver parenchyma increased with age, while those of the CCC did not show pertinent changes. Significant differences between the contents of CCC in malignant liver tumours and normal liver parenchyma were not observed, because in patients and volunteers normal liver tissue showed a large variability in the content of CCC.

Magnetic resonance imaging of the cranial nerves in the posterior fossa: a comparative study of t2-weighted spin-echo sequences at 1.5 and 3.0 tesla.

BACKGROUND: High-field magnetic resonance imaging (MRI) at 3.0 Tesla (T) is rapidly gaining clinical acceptance. Whether doubling of the field strength of 1.5T and the subsequent increase in signal-to-noise ratio (SNR) leads to a significant improvement of image quality is not automatically given. PURPOSE: To evaluate the depiction of fine anatomic detail in the posterior fossa, focusing on brain nerves, on T2-weighted imaging, and to define the potential advantage of imaging at 3.0T versus 1.5T. MATERIAL AND METHODS: In total, 10 brainstem nerve pairs of 12 volunteers were identified on T2-weighted MR images of 2- and 5-mm section thickness acquired at 1.5T and 3.0T. The MR images were compared for each subject at both field strengths by three independent readers who rated image quality according to depiction of anatomic detail and contrast by using a rating scale. RESULTS: In general, MR images at 3.0T were considered more conspicuous and less noisy than images at 1.5T. The SNR value measured was almost doubled. With respect to structural identification and contrast according to the rating scale, observer scores were significantly improved both for standard imaging with 5-mm sections and high-resolution imaging with 2-mm sections at 3.0T. Direct comparison revealed a significant increase for evaluated image quality criteria and the number of nerves detected. CONCLUSION: The comparison revealed a clear advantage in favor of T2-weighted MRI at 3.0T vs. 1.5T in depicting the roots and course of brain nerves in the posterior fossa.

MR-guided interstitial laser thermotherapy of colorectal liver metastases: efficiency, safety and patient survival.

PURPOSE: Evaluation of MR-guided interstitial laser thermotherapy (ILT) of colorectal liver metastases under consideration of efficacy, safety and patient survival. MATERIALS AND METHODS: Sixty-six inoperable patients with a total of 117 colorectal liver metastases were treated with MR-guided laser therapy in 96 sessions. 40.9% of patients presented metastases from rectum carcinoma, 30.3% from sigmoid carcinoma and 28.8% from colon carcinoma. Inclusion criteria were < or =5 metastases < or =5 cm in greatest diameter and no extrahepatic tumor spread. Internally water-cooled 9F power-laser-applicators were placed under CT-fluoroscopy. For MR-guided ILT, a 1064 nm Nd-YAG-lasers with a beam divider with multi applicator technique was used. The energy applied was 10 watt per centimeter diffusor length, with the diffusor length ranging from 20 to 40 mm. The mean duration of the energy application was 23 minutes (range: 15 - 37 minutes). The endpoint of the laser ablation was defined as the absence of hyperintense tumor tissue in the continuously monitored T2-w fat saturated gradient-echo sequences. Follow-up included contrast-enhanced MRI using T1- and T2-weighted spin-echo and gradient-echo sequences every three months after treatment. Survival times were calculated using the Kaplan-Meier method. RESULTS: The median follow-up was 8.7 months (mean 11.8; standard deviation 9.9; range 1 to 36). The overall median progression free survival was 6.1 months (range, 0.3 to 27+ months). Median survival was 23 months (95% CI, 17-29 months). The rate of major complications was 2.1% (n = 2) and peri-procedural mortality (30 days) was 3% (n = 2). After 3, 6, 9, and 12 months, local tumor control was 98.3%, 91.4%, 76.1%, and 69.4%, respectively. In no patient metastatic deposits along the catheter access route were found. CONCLUSIONS: In patients with colorectal liver metastases, interstitial laser thermotherapy is an effective and safe therapeutic option and therefore suitable not only in palliative situations.

Colon dissection: a new three-dimensional reconstruction tool for computed tomography colonography.

PURPOSE: To improve the sensitivity of computed tomography (CT) colonography in the detection of polyps by comparing the 3D reconstruction tool "colon dissection" and endoluminal view (virtual colonoscopy) with axial 2D reconstructions. MATERIAL AND METHODS: Forty-eight patients (22 M, 26 F, mean age 57 +/- 21) were studied after intra-anal air insufflation in the supine and prone positions using a 16-slice helical CT (16 x 0.625 mm, pitch 1.7; detector rotation time 0.5 s; 160 mAs und 120 kV) and conventional colonoscopy. Two radiologists blinded to the results of the conventional colonoscopy analyzed the 3D reconstruction in virtual-endoscopy mode, in colon-dissection mode, and axial 2D slices. RESULTS: Conventional colonoscopy revealed a total of 35 polyps in 15 patients; 33 polyps were disclosed by CT methods. Sensitivity and specificity for detecting colon polyps were 94% and 94%, respectively, when using the "colon dissection", 89% and 94% when using "virtual endoscopy", and 62% and 100% when using axial 2D reconstruction. Sensitivity in relation to the diameter of colon polyps with "colon dissection", "virtual colonoscopy", and axial 2D-slices was: polyps with a diameter >5.0 mm, 100%, 100%, and 71%, respectively; polyps with a diameter of between 3 and 4.9 mm, 92%, 85%, and 46%; and polyps with a diameter < 3 mm, 89%, 78%, and 56%. The difference between "virtual endoscopy" and "colon dissection" in diagnosing polyps up to 4.9 mm in diameter was statistically significant. CONCLUSION: 3D reconstruction software "colon dissection" improves sensitivity of CT colonography compared with the endoluminal view.

Effect of dose on image quality in a detector-based dual-exposure, dual-energy system for chest radiography.

PURPOSE: To assess the image quality of subtracted soft tissue and bone images of a CsI-detector-based dual-energy system for chest radiography at varying dose levels. MATERIAL AND METHODS: We evaluated a CsI-detector-based, dual-exposure, dual-energy prototype system; 126 patients were categorized into groups of small, medium, and large. Fixed values were applied for mAs and mA. The patients were randomized into two groups with intended higher and lower speed pairs of approximately 400/1000 (high and low energy shot) and 200/500, respectively. True speed equivalents were calculated retrospectively using the detector dose. Image quality was evaluated by two highly experienced radiologists in consensus applying a rating scale of 1 to 5 for quality indicators such as image noise, residual bone structures, motion artifacts, and others. RESULTS: Significantly decreased noise and a significant improvement for display of bone details in the bone image were noted with the higher dose, whereas a significant increase in motion artifacts reduced image quality at the higher dose. CONCLUSION: Radiation dose did not significantly influence the perception of dual-energy image quality. Dual-energy subtraction, as described, has the potential to become a future routine application in chest radiography.

Magnetic resonance imaging of hyaline cartilage defects at 1.5T and 3.0T: comparison of medium T2-weighted fast spin echo, T1-weighted two-dimensional and three-dimensional gradient echo pulse sequences.

PURPOSE: To evaluate and compare the diagnostic accuracy of appropriate magnetic resonance (MR) sequences in the detection of cartilage lesions at 1.5T and 3.0T. MATERIAL AND METHODS: Twelve chondral defects of varying depths, widths, and locations were created in the retropatellar hyaline cartilage in six sheep cadaver limbs. Axial images employing three fat-suppressed imaging sequences--(1) a T2-weighted fast spin-echo (FSE) sequence, (2) a two-dimensional (2D) and (3) three-dimensional (3D) gradient-echo (GE) sequence at 1.5T and 3.0T using an extremity quadrature coil--were evaluated by three experienced radiologists. Statistical analysis of the results consisted of receiver operating characteristics (ROC) and significant testing using the bivariate chi-square test. In addition, signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were evaluated with significance testing using the Wilcoxon test. RESULTS: The 3D GE sequence compared favorably with other sequences at 3.0T and 1.5T (Az=0.88 at 3.0T and Az=0.85 at 1.5T) missing only one small grade 2 lesion. 2D GE imaging was inferior to 3D imaging at both field strengths (P<0.05) in general. However, compared to 1.5T, lesion detectability was improved at the higher magnetic field of 3.0T (Az=0.81 and 0.73 at 3.0T and 1.5T, respectively). FSE images showed significantly inferior sensitivity and less anatomical detail compared to the GE sequences at both field strengths (Az=0.64 and 0.72 at 3.0T and 1.5T, respectively; P<0.05). However, compared to 1.5T, lesion detectability SNR and CNR values were superior in all sequences tested at 3.0T. CONCLUSION: MRI at 3.0T improves SNR and CNR significantly in the most common sequences for cartilage MRI, resulting in an improvement in chondral lesion detection. GE imaging therefore allows resolution to be increased in an acceptable time manner for patient comfort, and the 3D GE fat-suppressed sequence at 3.0T appears to be best suited for cartilage imaging in a clinical setting.