Comparison of Optimized 3D-SPACE and 3D-TSE Sequences at 1.5T MRCP in the Diagnosis of Choledocholithiasis.

PURPOSE: The aim of the study was to evaluate whether or not MRCP using a 3D-SPACE sequence allows for better image quality and a higher level of diagnostic confidence than a conventional 3D-TSE sequence at 1.5 T regarding the diagnosis of choledocholithiasis in a routine clinical setting. MATERIALS AND METHODS: 3D-SPACE and 3D-TSE sequences were performed in 42 consecutive patients with suspected choledocholithiasis undergoing MRCP. Evaluation of image quality and diagnostic confidence was done on the pancreaticobiliary tree which was subdivided into 10 segments. They were scored and statistically evaluated separately for visibility and diagnostic certainty by three radiologists with differing levels of experience on a five-point scale of 1 to 5 and -2 to 2, respectively. Student t-test was performed, and the interobserver agreement was also calculated. RESULTS: Image quality for each segment was significantly better for the 3D-SPACE sequence compared to the 3D-TSE sequence (4.48 ±â€Š0.94 vs. 3.98 ±â€Š1.20; 5-point scale p < 0.01). Diagnostic confidence for the reporting radiologist was also significantly better for 3D-SPACE than for 3D-TSE (1.68 ±â€Š0.56 vs. 1.46 ±â€Š0.70; 3-point scale; p < 0.01). The interobserver agreement was high in both sequences, 0.62 - 0.83 and 0.64 - 0.82, respectively. CONCLUSION: The optimized 3D-SPACE sequence allows for better image quality in 1.5 T MRCP examinations and leads to a higher diagnostic confidence for choledocholithiasis compared to the conventional 3D-TSE sequence. KEY POINTS: • 3D-SPACE allows for better image quality in 1.5 T MRCP.• This leads to a higher diagnostic confidence particularly in the periampullary region.• 3D-SPACE should be considered to substitute conventional 3D-TSE sequences in clinical routine MRCP.

Assessment of image quality and low-contrast detectability in abdominal CT of obese patients: comparison of a novel integrated circuit with a conventional discrete circuit detector at different tube voltages.

OBJECTIVES: To compare image quality and low-contrast detectability of an integrated circuit (IC) detector in abdominal CT of obese patients with conventional detector technology at low tube voltages. METHODS: A liver phantom with 45 lesions was placed in a water container to mimic an obese patient and examined on two different CT systems at 80, 100 and 120 kVp. The systems were equipped with either the IC or conventional detector. Image noise was measured, and the contrast-to-noise-ratio (CNR) was calculated. Low-contrast detectability was assessed independently by three radiologists. Radiation dose was estimated by the volume CT dose index (CTDIvol). RESULTS: The image noise was significantly lower, and the CNR was significantly higher with the IC detector at 80, 100 and 120 kVp, respectively (P = 0.023). The IC detector resulted in an increased lesion detection rate at 80 kVp (38.1 % vs. 17.2 %) and 100 kVp (57.0 % vs. 41.0 %). There was no difference in the detection rate between the IC detector at 100 kVp and the conventional detector at 120 kVp (57.0 % vs. 62.2 %). The CTDIvol at 80, 100 and 120 kVp measured 4.5-5.2, 7.3-7.9 and 9.8-10.2 mGy, respectively. CONCLUSIONS: The IC detector at 100 kVp resulted in similar low-contrast detectability compared to the conventional detector with a 120-kVp protocol at a radiation dose reduction of 37 %.

[Rational imaging of hepatocellular carcinoma. The challenge of multimodal diagnostic criteria]. / Rationale Schnittbildgebung des hepatozellulären Karzinoms. Die Herausforderung multimodaler Diagnosekriterien.

CLINICAL/METHODICAL ISSUE: Both computed tomography (CT) and magnetic resonance imaging (MRI) constitute the gold standard in radiological imaging of hepatocellular carcinoma (HCC). In cases of typical contrast behavior each modality as a single dynamic technique allows the diagnosis of HCC. There is still a challenge in detection of small HCCs < 2 cm, in differentiating HCC and high-grade dysplasia from other benign liver lesions as well as the evaluation of hypovascular liver lesions in the cirrhotic liver. PERFORMANCE: Nowadays, both modalities achieve high detection rates of 90-100 % for lesions > 2 cm. Regarding lesions between 1 and 2 cm there is a higher sensitivity for MRI ranging between 80 and 90 % compared to 60-75 % with CT. Besides the multimodal diagnostic criteria, MRI provides significant benefits with the use of hepatobiliary contrast. Especially in combination with diffusion- weighted imaging (DWI) increased sensitivity and diagnostic accuracy compared to CT has been described for lesions sized < 2 cm. Regarding the differentiation from other hepatic nodules in the cirrhotic liver there is strong evidence that the coexistence of arterial enhancement and hypointensity on hepatobiliary imaging is specific for HCC. Moreover, hypointensity on hepatobiliary imaging is associated with a high positive predictive value (PPV) of up to 100 % for the presence of high-grade dysplasia and HCC. ACHIEVEMENTS: The use of MRI including hepatobiliary imaging and DWI has to be regarded as the best non-invasive imaging modality for the detection of HCC and for the characterization of nodules in patients with liver cirrhosis. In comparison to CT there are benefits regarding detection of small lesions < 2 cm and evaluation of hypovascular liver lesions in the context of the hepatocarcinogenesis including prognostic values of premalignant lesions. PRACTICAL RECOMMENDATIONS: Both MRI and CT provide a high diagnostic performance in evaluation of HCC in liver cirrhosis. With MRI there are considerable advantages regarding the detection rate and specificity. For daily clinical routine, CT offers a fast, reliable and easy available modality with benefits for patients in reduced general state of health and restricted compliance.

Computed tomography for pulmonary embolism: assessment of a 1-year cohort and estimated cancer risk associated with diagnostic irradiation.

BACKGROUND: The principal concern of any radiation exposure in computed tomography (CT) is the induction of stochastic risks of developing a radiation-induced cancer. The results given in this manuscript will allow to (re-)calculate yield of chest CT. PURPOSE: To demonstrate a method to evaluate the lifetime attributable risk (LAR) of cancer incidence/mortality due to a single diagnostic investigation in a 1-year cohort of consecutive chest CT for suspected pulmonary embolism (PE). MATERIAL AND METHODS: A 1-year cohort of consecutive chest CT for suspected PE using a standard scan protocol was analyzed retrospectively (691 patients, 352 men, 339 women). Normalized patient-specific estimations of the radiation doses received by individual organs were correlated with age- and sex-specific mean predicted cancer incidence and age- and sex-specific predicted cancer mortality based on the BEIR VII results. Additional correlation was provided for natural occurring risks. RESULTS: LAR of cancer incidence/mortality following one chest CT was calculated for cancer of the stomach, colon, liver, lung, breast, uterus, ovaries, bladder, thyroid, and for leukemia. LAR remains very low for all age and sex categories, being highest for cancer of the lungs and breasts in 20-year-old women (0.61% and 0.4%, respectively). Summation of all cancer sites analyzed raised the cumulative relative LAR up to 2.76% in 20-year-old women. CONCLUSION: Using the method presented in this work, LAR of cancer incidence and cancer mortality for a single chest CT for PE seems very low for all age groups and both sexes, but being highest for young patients. Hence the risk for radiation-induced organ cancers must be outweighed with the potential benefit or a treatment and the potential risks of a missed and therefore untreated PE.

Transthoracic sonography for the detection of pulmonary embolism--a meta-analysis.

PURPOSE: Radiation protection is a major issue since the implementation of MSCT technology and its widespread indication for the detection of various diseases. In a European-wide trial (SECT) meta-analyses of imaging alternatives to CT have been initiated. This paper focuses on the diagnostic performance of transthoracic ultrasound (TUS) for the diagnosis of pulmonary embolism (PE) (5 studies, 652 patients). MATERIALS AND METHODS: Medical literature (from 1990 to 2006) in PubMed and EMBASE databases was searched for articles on studies that used TUS as diagnostic tests for PE. Studies were included if they reported the positive and negative rates of PE diagnoses from TUS compared with the rates of PE in CT, MRI or a combination of diagnostic tests. Two readers assessed the quality of the studies. RESULTS: Pooled sensitivity and specificity of TUS for PE were 80 % (95 % CI: 75 %, 83 %) and 93 % (95 % CI: 89 %, 96 %), respectively. CONCLUSION: In the time of MSCT, TUS is an imaging modality that is no longer part of recent diagnostic algorithms for the diagnosis of PE. Considering the increasing number of requested CT examinations and therefore increasing collective radiation dose, this meta-analysis shows that TUS is a diagnostic alternative for special clinical settings in the work-up of suspected PE that seems to have fallen into oblivion.

Total-body contrast-enhanced MRA on a short, wide-bore 1.5-T system: intra-individual comparison of Gd-BOPTA and Gd-DOTA.

Total-body contrast-enhanced MRA (CE-MRA) provides information of the entire vascular system according to a one-stop-shop approach. Short, wide-bore scanners have not yet been used for total-body CE-MRA, probably due to their restricted field of view in the z-direction. The purpose of this feasibility study is to introduce an image protocol for total-body MRA on a short, wide-bore system. The protocol includes five to six table-moving steps and two injection runs. Two pharmacologically different contrast materials (CM) were applied in ten healthy volunteers in view of possible CM-dependent influences on the protocol outcome (Gd-Bopta, Gd-Dota). Differences consisted of significantly higher CNR with Gd-Bopta with a mean of 73.8+/-38.7 versus 69.1+/-34.3 (p=0.008), significantly better arterial visualization values with Gd-Dota with a mean of 1.26+/-0.44 versus 1.53+/-0.73 (p=0.003) and a tendency to less venous overlay with Gd-Dota, mean 1.19+/-0.44 and 1.34+/-0.72, respectively (p=0.065) (two-tailed Wilcoxon matched-pairs test). Overall 94% of the steps were valued as qualitatively excellent or good. The good results with both CM suggest a transfer to further patient evaluation.

Effect of bolus length of intraarterial injections on contrast-enhanced MR-angiography in patients.

PURPOSE: To perform MR-guided interventions, repetitive injections of contrast agent in the arterial system are necessary. By reducing the intraarterial bolus length during image acquisition and consecutively reducing the gadolinium-chelate-based contrast agent dose, we focus on a comparable vascular depiction. The tradeoff in reducing bolus length is vascular depiction. MATERIALS AND METHODS: Intraarterial gadolinium-chelate injection was performed to depict the femoropopliteal artery and infrapopliteal arteries in six patients. Six measurements with a bolus length of 20% to 100% of the total acquisition time were performed (three-dimensional [3D] Turbo-fast low-angle shot (FLASH) sequence, 1.5 T). Contrast-to-noise ratio (CNR) was determined and a consensus reading of vascular depiction was performed. RESULTS: CNR values comparable 100% of bolus length were obtained for the femoropopliteal artery at >or=40% and for the infrapopliteal arteries at >or=60%. Qualitative analysis demonstrated that a bolus length of >or=60% is necessary to reveal a good diagnostic vascular depiction. CONCLUSION: Quantitatively, a reduction of intraarterial gadolinium-chelate dosage in patients is possible down to 40% in the femoropopliteal artery and to 60% in the infrapopliteal arteries to acquire a CNR comparable to 100% of bolus length. Qualitatively, however, the bolus length can only be reduced down to 60% for both level to produce a good diagnostic vascular depiction and is, for diagnostic purposes, the limiting factor.

[Presentation of right lower quadrant pain with atypical findings]. / Rechtsseitige Unterbauch- schmerzen mit atypischem Befund.

We present a 57-year old male patient with symptoms of an acute appendicitis. Surprisingly, preoperative sonography revealed an atypical cystic mass in the right lower quadrant of the abdomen with signs of sedimentation. Laparoscopy showed a ruptured appendiceal mucocele with peritoneal adherent mucus. The patient was treated with ileocecal resection. Histopathological examination revealed an infiltrating mucinous cystadenocarcinoma of the appendix. The patient will be treated with adjuvant intraperitoneal chemotherapy. Despite typical clinical signs of appendicitis a sonographically atypical cystic mass in the right lower abdomen should raise suspicion of a mucocele, eventually on the base of a neoplasm.

["Fat halo sign of the colon": not only in patients with inflammatory bowel disease. An illustrated case-report]. / Das "Fett-Halo-Zeichen" des Kolon im CT: Indikator einer inflammatorischen Darmwanderkrankung oder Normal-Variante? Ein illustrierter Fallbericht.

A 76-year old man was referred for radiological evaluation of recurrent left sided flank pain, micro-haematuria and renal cysts. Computer tomographic findings were colon wall-thickening and submucosal fat (fat halo sign) throughout the entire length of the colon. Fat halo sign is thought to be a reliable marker for inflammatory bowel disease. It has also been reported in patients receiving cytoreductive therapy or in patients with graft-versus-host disease. A relation between short segment fat halo sign and obesity in asymptomatic patients is presumed. None of these conditions apply for this patient without evidence of previous or present gastrointestinal disease. The striking changes of the colon wall are exceptional, although they have to be considered as a normal finding.

Low-dose intra-arterial contrast-enhanced MR aortography in patients based on a theoretically derived injection protocol.

Multiple intra-arterial contrast agent injections are necessary during MR-guided endovascular interventions. In respect to the approved limits of maximum daily gadolinium dose, a low-dose injection protocol is mandatory. The objective of this study was to derive and apply a low-dose injection protocol for intra-arterial 3D contrast-enhanced MR aortography in patients. Injection rate (Qinj), concentration of injected gadolinium [Gd]inj and aortal blood flow rate (Qblood) were included for the theoretical evaluation of signal intensity (SI) of the arterial lumen. SI simulations were carried out at Qinj=2 versus 4 ml/s in the [Gd]inj range between 0-500 mM. Qinj and [Gd]inj with SI above the 75% threshold of the maximal SI were regarded as optimal injection parameters. [Gd]inj=50 mM and Qinj=4 ml/s were considered as optimal and were administered in five patients for 3D MR aortography. All images revealed clear delineation of the abdominal aorta and its major branches. Mean+/-SD of contrast-to-noise ratios of the abdominal aorta, common iliac and renal artery were 70.2+/-15.2, 58.6+/-12.3 and 67.4+/-12.3. Approximately seven intra-aortal injections would be permissible in patients during MR-guided interventions without exceeding the maximal dose of gadolinium.

[Chronic thoracic vertebral syndrome by roundabout diagnosis]. / Chronisches Thorakovertebralsyndrom auf Umwegen.

Back pain, especially in the lumbar region is a frequent symptom in ambulatory medicine. The differential diagnosis is wide and ranges from rather harmless muscular distortions to systematic disease, such as chronic infections or cancer. Our case shows, that sometimes the diagnosis is not quite simple to determine. A atypically picture may lead to unnecessary further evaluations and in some case even invasive diagnostic tests. However, the benefit should overweight the harm and costs. Not every back pain needs to be examined in every case and with every diagnostic possibility. Recent guidelines recommend a conservative approach to patients with back pain if they are younger than 50 years of age and if cancer or chronic infection is not suspected from their clinical evaluation and past medical history. For patients older than 50 years of age and suspicion for systematic disease, a radiograph of the spine and a routine laboratory measurement, including markers of inflammation (e.g. C-reactive protein), alkaline phosphatase, PSA (prostate-specific antigen) and immune-electrophoresis is mandatory. More detailed diagnostic steps, e.g. CT or MRT, should be performed if symptoms persist for longer than 6 weeks. In addition, if symptoms do not resolve with analgesia and physiotherapy more invasive therapeutically options may be considered.

Cuff-compression of the proximal calf to reduce venous contamination in contrast-enhanced stepping-table magnetic Resonance angiography.

PURPOSE: To minimize venous overlay at the calf station in contrast-enhanced three-dimensional (3D) stepping-table magnetic resonance angiography (MRA) using a continuous cuff-compression technique during MR data acquisition. MATERIAL AND METHODS: Within 14 months, 32 patients suffering from symptomatic peripheral arterial occlusive disease (PAOD) with a bilateral ankle-brachial index (ABI) of 0.8 or below were consecutively enrolled in this study. Unilateral cuff-compression of the proximal calf was applied in the study group (n = 14). The control group (n = 18) underwent no compression. All patients underwent three-step 3D contrast-enhanced magnetic resonance angiography (3D CE-MRA) according to the institute's protocol. Venous contamination scores (vcs) at the calf station were blindly ranked by a 1 to 3 rating score (3 = major venous contamination). The vcs values of the control group were regarded as standard. Statistical significance between both groups was evaluated with a paired t test. RESULTS: Symmetric venous contamination was observed within the control group with a mean vcs of 2.2+/-0.6 on the left side and 2.2+/-0.7 on the right side with deltavcsleft-right of 0.1+/-0.2 (P>0.1). In the study group, asymmetric venous contamination was determined with vcsmean = 2.3+/-0.6 for the uncompressed side and vcsmean =1.4+/-0.5 for the compressed side and a deltavcsuncomp-comp of 0.9+/-0.5 (P<0.00005). The control group and the uncompressed side of the study group showed no significant difference in venous contamination (P > 0.1). CONCLUSION: Subdiastolic cuff-compression of the proximal calf is an easily applicable and inexpensive technique by which to reduce venous contamination of the calf station in stepping-table MR angiography and to improve evaluation of the infrapopliteal arteries.

Unenhanced helical computed tomography vs intravenous urography in patients with acute flank pain: accuracy and economic impact in a randomized prospective trial.

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted alternative to intravenous urography (IVU) in patients with acute flank pain and suspected ureterolithiasis. The purpose of our randomized prospective study was to analyse the diagnostic accuracy of UHCT vs IVU in the normal clinical setting with special interest on economic impact, applied radiation dose and time savings in patient management. A total of 122 consecutive patients with acute flank pain suggestive of urolithiasis were randomized for UHCT ( n=59) or IVU ( n=63). Patient management (time, contrast media), costs and radiation dose were analysed. The films were independently interpreted by four radiologists, unaware of previous findings, clinical history and clinical outcome. Alternative diagnoses if present were assessed. Direct costs of UHCT and IVU are nearly identical (310/309 Euro). Indirect costs are much lower for UHCT because it saves examination time and when performed immediately initial abdominal plain film (KUB) and sonography are not necessary. Time delay between access to the emergency room and start of the imaging procedure was 32 h 7 min for UHCT and 36 h 55 min for IVU. The UHCT took an average in-room time of 23 min vs 1 h 21 min for IVU. Mild to moderate adverse reactions for contrast material were seen in 3 (5%) patients. The UHCT was safe, as no contrast material was needed. The mean applied radiation dose was 3.3 mSv for IVU and 6.5 mSv for UHCT. Alternative diagnoses were identified in 4 (7%) UHCT patients and 3 (5%) IVU patients. Sensitivity and specificity of UHCT and IVU was 94.1 and 94.2%, and 85.2 and 90.4%, respectively. In patients with suspected renal colic KUB and US may be the least expensive and most easily accessable modalities; however, if needed and available, UHCT can be considered a better alternative than IVU because it has a higher diagnostic accuracy and a better economic impact since it is more effective, faster, less expensive and less risky than IVU. In addition, it also has the capability of detecting various additional renal and extrarenal pathologies.

Three-dimensional dynamic MR-hysterosalpingography; a new, low invasive, radiation-free and less painful radiological approach to female infertility.

BACKGROUND: The purpose of this study was to propose a new method for imaging the uterine cavity and Fallopian tube patency by three-dimensional dynamic magnetic resonance hysterosalpingography (3D dMR-HSG) and to analyse if, by using a higher viscosity contrast solution, direct visualization of the Fallopian tubes may be achieved by this new technique. METHODS: 10 consecutive infertile women underwent 3D dMR-HSG and conventional HSG as gold standard. 3D dMR-HSG consisted of injection of 20 ml of a gadolinium-polyvidone solution into the uterine cavity while acquiring five consecutive three-dimensional (3D) T1-weighted MR-sequences. RESULTS: In three patients the catheter became dislodged during 3D dMR-HSG. However, in one of these patients the examination was still partially diagnostic. Imaging findings of 3D dMR-HSG showed good correlation with conventional hysterosalpingography and allowed 3D imaging of the uterine cavity and of Fallopian tube patency in 8/10 patients and direct visualization of the Fallopian tubes in 5/7 patients. CONCLUSION: 3D dMR-HSG represents a new and promising imaging approach to female infertility causing less pain and avoiding exposure of the ovaries to ionizing radiation. By using a higher viscosity MR-contrast agent it allows not only visualization of uterine cavity and Fallopian tube patency but also direct visualization of Fallopian tubes.

Dynamic time-resolved contrast-enhanced two-dimensional MR projection angiography of the pulmonary circulation: standard technique and clinical applications.

OBJECTIVE: Time-resolved pulmonary two-dimensional MR projection angiography is a fast acquisition technique that allows the generation of dynamic projection angiograms by a method similar to that used to generate digital subtraction angiograms. MR images are obtained after subtracting the mask defined at the beginning of the sequence from later images, thus generating time-resolved continuous projection angiograms that depict the passage of a bolus through the pulmonary circulation. This article describes the application of this novel technique in three patients with pathologic conditions not previously described with this modality and two control subjects. CONCLUSION: The analysis of the findings on dynamic time-resolved contrast-enhanced two-dimensional MR projection angiography shows that this technique is useful not only in revealing morphologic changes associated with pulmonary disorders but also in following the passage of the bolus through the cardiopulmonary circulation. The latter capability allows qualitative detection of normal or abnormal pathways and thus is potentially of value in the assessment of several pulmonary disorders.