[Rational imaging of hepatocellular carcinoma. The challenge of multimodal diagnostic criteria]

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.

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]

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]

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.

[Controversies on screening mammography]

Brustkrebs ist die häufigste Krebserkrankung und Krebstodesursache der Frau in den industrialisierten Ländern. Bislang gibt es weder sinnvolle Präventionsmassnahmen, noch Vorsorgeuntersuchungen. Die Mammographie stellt zur Zeit die einzige akzeptable diagnostische Modalität zur Früherkennung und -therapie dar. Sie ist mit einer in Gross-Studien belegten Reduktion der Mortalitätsrate von 30% als Screeningverfahren geeignet und empfohlen und wird in den meisten europäischen Ländern schon durchgeführt.

[Chronic thoracic vertebral syndrome by roundabout diagnosis]

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.

[MR-diagnostig of arthrosclerosis]

Eine umfassende Arterioskleroseabklärung sollte die Beurteilung des Gefässlumens aber auch der Gefässwandung – insbesondere der biochemisch-histologischen Zusammensetzung der Arterioskleroseplaques – ermöglichen. Die Darstellung des Gefässlumens gelingt mit Hilfe der kontrastmittelverstärkten MR-Angiographie. Sie erlaubt, Gefässstenosen und -verschlüsse sowohl gezielt als auch in der Übersicht mit ausreichender diagnostischer Qualität darzustellen. Im Gegensatz zur DSA – dem Goldstandard der Angiographie - ist die MR-Angiographie minimal invasiv, verwendet ausgesprochen gut-nierenverträgliche Kontrastmittel und verzichtet auf den Einsatz ionisierender Strahlung. Zusätzlich sind die Gefässe dreidimensional darstellbar und der Weichteilkontrast ist ausgezeichnet.Die histomorphologische Charakterisierung von Arterioskleroseplaques gelingt mit der räumlich hochaufgelösten, kontrastmittelverstärkten MR-Tomographie und wird in der präklinischen Phase der Arterioskleroseforschung eingesetzt. Eine endgültige Validierung hinsichtlich des klinischen Einsatzes steht jedoch noch aus.

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.

[Palpation of the male breast: a diagnostic dilemma]

Gerade weil das Mammakarzinom beim Mann eine so seltene Erkrankung ist, besteht gelegentlich Unsicherheit bzgl. der Art und Agressivität der Abklärung beim Tastbefund in der männlichen Brust. Generell sollte jeder solide Herdbefund einer bildgebenden Diagnostik zugeführt werden mit einer geringen Schwelle zur weiteren zytologischen oder histologischen Abklärung. Eine sorgfältige Anamneseerhebung ist entscheidend für die Eruierung eines potentiellen metastatischen Befalls, was wiederum anstelle eines operativ-kurativen Therapieansatz lediglich eine Palliation zur Folge hätte.

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.

CT findings in eosinophilic enterocolitis with predominantly serosal and muscular bowel wall infiltration

A 44-year-old female presented with tenderness of her abdomen, vomiting, intestinal obstruction, hypoalbuminemia and blood eosinophilia. Gastroscopy was normal and colonoscopic biopsies showed only non-specific inflammation of the colonic mucosa and submucosa. CT revealed large amounts of ascites and bilateral pleural effusions but eosinophil counts in the ascites were normal. At CT the jejunum was dilated and showed marked prominence of the valvulae whereas the ileum and the colon presented with a diffuse and hypoattenuating bowel wall thickening. The bowel wall thickening was most pronounced in the colon which especially showed also an impressive thickening and hyperenhancement mainly of its outer bowel wall layers. Parasitic infection could be excluded as well as a specific allergic response. In context with the known blood eosinophilia the diagnosis of an eosinophilic enterocolitis was suspected already by CT but finally only surgical full thickness biopsies could confirm the rare diagnosis of an eosinophilic enterocolitis with predominantly serosal and muscular bowel wall infiltration.

Multi-centre clinical study evaluating the efficacy of SonoVue (BR1), a new ultrasound contrast agent in Doppler investigation of focal hepatic lesions

OBJECTIVES

SonoVue is a new ultrasound contrast agent, which consists of stabilised microbubbles of a sulphur hexafluoride gas. The aim of the study was to assess its efficacy in the Doppler investigation of focal hepatic lesions.

MATERIALS AND METHODS

Seventy patients with focal liver tumours were studied. Four doses (0.3, 0.6, 1.2 and 2.4 ml) of SonoVue were administered intravenously with at least 10 min delay between each injection. A complete colour/power and spectral Doppler imaging investigation of the lesions was performed at baseline pre-dosing and after each SonoVue injection. All examinations were recorded on SVHS videotapes. Baseline and post contrast videotapes were reviewed by the on-site (un-blinded) investigators and by two off-site blinded readers (a) to grade the global quality of the Doppler scans of the focal lesions vascularity and the normal parenchymal vessels (b) to measure the duration of clinically useful Doppler signal enhancement and (c) to determine the diagnostic accuracy and performance of the enhanced versus unenhanced scans using histopathology, tumour markers, CT and/or MR as the reference standard.

RESULTS

A statistically significant improvement was observed at all four SonoVue doses in the off site assessment of global quality of the Doppler examination of tumoral and normal parenchymal vessels in comparison with the baseline (P < 0.05). The median duration of clinically useful enhancement was significantly increased with increasing doses (P < 0.001), ranging between 1.4-2.2 min for the lowest dose and 3.2-3.8 min for the highest dose for the off-site readers. On-site assessment of diagnostic accuracy showed a significant increase in the specificity of the Doppler diagnoses (P < 0.0016) with an increase in the positive and negative predictive values and in the likelihood ratio in differentiating between benign and malignant lesions. Off-site evaluation showed a significant increase in the accuracy of enhanced Doppler diagnosis in comparison with the baseline performance.

CONCLUSION

The results suggest that SonoVue is effective in improving the display of tumoral vascularisation and may be useful in the characterisation of focal liver lesions.

Magnetic resonance imaging of metastatic disease to the brain with gadobenate dimeglumine

Seventy-four patients with one to eight proven intraaxial brain metastases received a total cumulative dose of 0.2 mmol/kg bodyweight gadobenate dimeglumine, administered as sequential injections of 0.05, 0.05 and 0.1 m mol/kg over a 20-min period. MR imaging was performed before the first administration (T2- and T1-weighted sequences) and after each injection of contrast agent (T1-weighted sequences only). Quantitative assessment of images revealed significant (P <0.01) dose-related increases in lesion-to-brain (L/B) ratio and percent enhancement of lesion signal intensity. Qualitative assessment by two independent, blinded assessors revealed additional lesions in 22%, 25% and 38% (assessor 1) and 29%, 32% and 34% (assessor 2) of patients after each cumulative dose when compared with combined T1- and T2-weighted pre-contrast images. Significantly more lesions (P < 0.01) were noted by both assessors after the first injection and by one assessor after each subsequent injection. For patients with just one lesion observed on unenhanced T1- and T2-weighted images, additional lesions were noted in 12%, 16% and 28% of patients by assessor 1 following each dose and in 24%, 27% and 30% of patients by assessor 2. Contemporaneously, diagnostic confidence was increased and lesion conspicuity improved over unenhanced MRI. For patients with one lesion observed after an initial dose of 0.05 mmol/kg, additional lesions were noted by assessors 1 and 2 in 9.1% and 11.8% of patients, respectively, after a cumulative dose of 0.1 mmol/kg and in a further 9.1% and 5.9% of patients, respectively, after a cumulative dose of 0.2 mmol/kg. No safety concerns were apparent.

Three-dimensional dynamic MR hysterosalpingography: a preliminary report

The aim of this study was to evaluate the feasibility of three-dimensional dynamic MR hysterosalpingography (3D MR HSG) for visualization of the cavum uteri and demonstration of bilateral fallopian tube patency as an alternative to conventional hysterosalpingography. Five infertile female patients underwent 3D dynamic MR HSG prior to conventional hysterosalpingography. The MR protocol consisted of axial T1-weighted spin-echo (SE), axial/coronal T2-weighted fast SE (FSE), and 3D MR angiography sequences before, during, and after injection of a diluted gadolinium solution into the cavum uteri via a balloon catheter. Positioning of the catheter was feasible in all patients. In one patient the catheter slipped out during MRI and in one patient the catheter was placed far in the cavum uteri. In three patients catheter position was optimal at the level of the cervical canal. Evaluation of pelvic anatomy, myometrium, and ovaries was possible in all patients on the basis of T1-weighted SE and T2-weighted FSE. Three-dimensional visualization of the dilated cavum uteri was possible in four patients. In these four patients 3D MR HSG also proved bilateral fallopian tube patency which was confirmed in each patient by conventional hysterosalpingography. Three-dimensional MR HSG is feasible and further research should be done to determine if this technique can evolve into an alternative technique to conventional hysterosalpingography with the advantages of no radiation and additional visualization of the uterus wall and ovaries.

Acute appendicitis in a young adult with midgut malrotation: a case report

Midgut malrotation is defined as a developmental anomaly that may cause atypical clinical symptoms in relatively common intestinal disorders due to altered anatomy. A 27-year-old woman presented with acute left-sided abdominal pain. Underlying type Ia malrotation prevented the correct clinical diagnosis of perforated, ulcerated appendicitis. Cross-sectional imaging demonstrated all the typical signs of this type of malrotation, i.e., right-sided duodenojejunal junction, left positioned cecum and ascending colon, inverted position of the superior mesenteric vessels, and hypoplasia of the uncinate process of pancreas, and surgical treatment was initiated.

Differentiation between benign and malignant findings on MR-mammography: usefulness of morphological criteria

The purpose of this study was to evaluate the usefulness of morphological criteria in differentiating between benign and malignant lesions on MR-mammography. Fifty-three women (18-82 years) with 62 lesions scheduled for excisional biopsy underwent dynamic contrast-enhanced MR-mammography using fast 3D Gradient-Echo sequences in coronal orientation (axial orientation in seven patients). Histology revealed 44 malignant and 18 benign lesions. For each lesion, five radiologists evaluated four morphological features: lesion shape, irregularity of contour, homogeneity of contrast enhancement and presence of ring enhancement. For each feature a receiver operating characteristic (ROC) curve was generated with calculation of the area under the curve (AUC). Interobserver variability was evaluated by the kappa-coefficient. The most reliable morphological feature indicating malignancy was an irregular lesion contour with a sensitivity/specificity/AUC of 83%/76%/0.9 followed by inhomogeneous contrast enhancement (85%/42%/0.7) and the presence of ring enhancement (71%/53%/0.64). The average interobserver agreement for the different features ranged between 0.35 and 0.4. Morphological criteria are useful features in MR-mammography for differentiating between benign and malignant lesions. However, due to the relatively high interobserver variability, standardization of terminology is important.

Preliminary experience with dynamic MR projection angiography in the evaluation of cervicocranial steno-occlusive disease

The application of a contrast-enhanced, two-dimensional MR technique, which provides dynamic projection angiograms at a subsecond temporal frame rate for depiction of the cervical and intracranial arteries, was evaluated in three healthy volunteers and seven patients with various cervicocranial steno-occlusive diseases. Intra-arterial digital subtraction angiography (DSA) served as standard of reference for findings in the patients. Magnetic resonance projection angiography (MRPA) was performed on a standard 1.5-T clinical MR imaging system at intravenous injection of a single dose of contrast agent (0.1 mmol/kg GdDTPA-BMA). Sixty consecutive images of the cerebral circulation were acquired at a temporal frame rate of 900 ms per image in the coronal plane. The collateral flow and the perfusion of the compromised vessel territory were readily assessed by MPRA in patients with occlusion of the internal cerebral artery (ICA) or middle cerebral artery (MCA). The leptomeningeal collateralisation of these patients was displayed in a dynamic fashion. Furthermore, quantitative perfusion measurement provided a difference between both MCA territories in the time to peak (deltaDTTP) of the contrast bolus of 1.12 +/- 0.28 s in five patients with severe stenosis or occlusion of the ICA (healthy volunteers 0.19 +/- 0.05 s). However, important pathological findings, such as the evaluation of carotid artery stenoses and the intracranial collateral flow pattern in patients with severe carotid stenoses, were not sufficiently assessable as compared with DSA. We conclude that the possibility of obtaining simultaneously information about morphology and perfusion dynamics of the cervicocranial vessels is unique in MPRA as compared with other MR techniques. However, in the applied form, the technique is not a reliable tool for the complete evaluation of the cervicocranial vessels in patients with steno-occlusive disease.

Imaging findings in idiopathic pelvic fibrosis

Two patients presented with ureteric obstruction, and voiding symptoms and constipation, respectively, and were examined by means of intravenous urography and computed tomography. One patient was additionally examined by means of MR tomography. After CT (performed in both patients) and MRT (performed in one patient) had shown a diffuse, contrast-enhancing, infiltrating process in the small pelvis with infiltration of adjacent organs and vessels, surgical biopsy proved the diagnosis of idiopathic pelvic fibrosis. Extension of retroperitoneal fibrosis below the pelvic rim is very rare. Clinical symptoms of pelvic fibrosis are variable and imaging findings may lead to a broad list of differential diagnoses. We present two patients with idiopathic pelvic fibrosis and discuss radiological findings and differential diagnoses of this rare disease.

Pitfalls and limitations of magnetic resonance imaging in chronic posttraumatic osteomyelitis

The aim of this study was to evaluate pitfalls and technical limitations of MR imaging in diagnosing relapse of chronic posttraumatic osteomyelitis of the lower extremities. Retrospective analysis of MR examinations in 15 patients (17 body areas) with suspected relapse of chronic posttraumatic osteomyelitis (at least 1.5 years duration/mean number of surgical procedures per patient: 5.8). The MRI findings were compared with postoperative bacteriology (n = 11) and clinical follow-up (n = 4). Five patients had additional CT examination. Magnetic resonance imaging identified all infected areas correctly, but five uninfected regions were diagnosed false positive due to postoperative scarring/oedema in bone defects (n = 4) and soft tissue (n = 1). Specificity of MRI in diagnosing active bone infection was 63% and sensitivity 100%. Additional CT was preoperatively necessary in 5 patients (33%) to further examine osteomyelitic and reparative bone remodeling. Metal artefacts were present in 11 patients, rendering complete evaluation impossible (n = 2) or considerably more difficult (n = 4). Scarring/oedema in postoperative bone defects occurs up to 13 months postoperatively and represents a major pitfall leading to low specificity. Definitive evaluation of suspected fistula, bony fragments and mineralization by MRI may be limited in this special patient group and requires additional CT in one third of patients. Metal artefacts occur in most patients and may impair or even prevent correct film evaluation in 23 and 11%, respectively.

Slow clearance gadolinium-based extracellular and intravascular contrast media for three-dimensional MR angiography

The objective of this study was to assess two new slow-clearance contrast media with extracellular and intravascular distribution for magnetic resonance angiography (MRA). Extracellular Gd-DTPA-BC(2)glucA and intravascular Gd(DO3A)(3)-lys(16) were developed within the European Biomed2 MACE Program and compared with two reference compounds, intravascular CMD-A2-Gd-DOTA and extracellular GdDOTA, in 12 rats. Pre- and post-contrast three-dimensional MR (TR/TE = 5 msec/2.2 msec; isotropic voxel size 0.86 mm(3)) was acquired for 2 hours. Signal-to-noise enhancement (DeltaSNR) was calculated. Two minutes after injection, all contrast media provided strong vascular signal enhancement. The DeltaSNR for Gd-DTPA-BC(2)glucA, Gd(DO3A)(3)-lys(16), CMD-A2-Gd-DOTA, and GdDOTA were 13.0 +/- 1.8, 25.0 +/- 3.2, 25.0 +/- 4.0, and 18.0 +/- 3.4, respectively. Gd-DTPA-BC(2)glucA, Gd(DO3A)(3)-lys(16), and CMD-A2-Gd-DOTA cleared slowly from the circulation, whereas GdDOTA cleared rapidly. Vascular DeltaSNR at 2 hours were 2.9 +/- 0.6, 25.0 +/- 3.2, 25.0 +/- 4.0, and 0.4 +/- 1.0. Gd(DO3A)(3)-lys(16) provided strong vascular and minor background enhancement, and thus may be useful for MRA or perfusion imaging. Gd-DTPA-BC(2)glucA produces persistent enhancement of extracellular water, and thus may allow quantification of extracellular distribution volume and assessment of myocardial viability.

Aneurysmal and partially thrombosed orifice of a coronary artery fistula into the right atrium combined with patent foramen ovale

We report a case of a right atrial sessile tumor combined with a patent foramen ovale and the characteristics of fat containing tumor in magnetic resonance imaging. Histologic study revealed this to be an aneurysmal and partially thrombosed formation of a coronary artery fistula.

[Percutaneous stereotactic biopsy of non-palpable breast lesions using the Advanced Breast Biopsy Instrumentation (ABBI) system: critical evaluation of indication strategies]

PURPOSE

To compare the indications for biopsy with and without the use of the Breast Imaging Reporting and Data System.

MATERIAL AND METHODS

Biopsies using the ABBI were performed in 62 patients with 64 non-palpable evident mammographic lesions. The initial decision for biopsy was made by non-radiologists due to suspicious microcalcifications (n = 53) and masses (n = 11). The indication was retrospectively reassessed by adopting the BI-RADS classification by three radiologists in consensus. The positive predictive value (PPV) of both indication strategies was assessed and compared.

RESULTS

Biopsies adopting ABBI were performed without major side-effects and were diagnostic. Carcinoma was present in 14 lesions: nine specimens were diagnosed as DCIS and five as invasive carcinomas. For the 50 benign lesions histology revealed mastopathies (26/50) and fibroadenomas (8/50) as the most frequent diagnosis. The positive predictive value (PPV) for the initial indication was 22%, whereas PPV for BI-RADS based indications (categories 4 and 5) was 31%.

CONCLUSION

ABBI enables stereotactically-guided procedures that result in representative and diagnostic biopsies. Standardized criteria like BI-RADS improve the PPV and should be a mandatory part of mammographic evaluation. Radiologists should remain involved in the decision making.

Omental infarction associated with right-sided heart failure

A 31-year-old man with a known congenital heart disease presented with cardial decompensation and an acute abdomen with tenderness in the right inferior abdominal quadrant. Because infectious parameters were slightly elevated, acute appendicitis was suspected. A CT scan showed an isolated focal infiltration of the omentum, superficial to the ascending colon, small amounts of ascites, and dilated hepatic and mesenteric veins. Laparoscopic resection and histopathologic examination confirmed hemorrhagic omental infarction due to thromboses of several small omental veins. This is a report on the pathogenesis, differential diagnoses, and CT findings of omental infarction.

Chronic post-traumatic osteomyelitis of the lower extremity: comparison of magnetic resonance imaging and combined bone scintigraphy/immunoscintigraphy with radiolabelled monoclonal antigranulocyte antibodies

OBJECTIVE

A retrospective study of the validity of combined bone scintigraphy (BS) and immunoscintigraphy (IS) using (99m)Tc-labelled murine antigranulocyte antibodies (MAB) and magnetic resonance imaging (MRI) in chronic posttraumatic osteomyelitis.

DESIGN AND PATIENTS

The results of MRI and combined BS/IS of 19 lesions in 18 patients (13 men, 5 women; mean age 45 years, range 27-65 years) were independently evaluated by two radiologists and one nuclear medicine physician with regard to bone infection activity and extent. The patient group was a highly selective collection of clinical cases: the average number of operations conducted because of relapsing infection was eight (range 2-27), the average time interval between the last surgical intervention and the present study was 6.5 years (range 3 months to 39 years), and from the first operation was 14 years (range 1.5-42 years). Interobserver agreement on MRI was measured by kappa statistics. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRI and the nuclear medicine studies.

RESULTS

For MRI/nuclear medicine, a sensitivity of 100%/77%, a specificity of 60%/50%, an accuracy of 79%/61%, a PPV of 69%/58% and a NPV of 100%/71% were calculated. Four MR examinations were false positives because of postsurgical granulation tissue. A high degree of interobserver agreement was found on MRI (kappa=0.88). A low-grade infection was missed on two scintigrams, while four were false positive because of ectopic haematopoietic bone marrow, and in one examination the anatomical distortion resulted in an inaccurate assignment of the uptake leading to false positive findings. Image analysis was frequently hindered by susceptibility artefacts due to residual abrasions of metallic implants after removal of orthopaedic devices (15/18 patients); this led to limited assessment in 17% (3/18 patients).

CONCLUSION

Acute activity in a chronic osteomyelitis can be excluded with high probability if the MRI findings are negative. In the first postoperative year fibrovascular scar cannot be distinguished accurately from reactivated infection on MRI and scintigraphy may improve the accuracy of diagnosis. MRI is more sensitive in low-grade infection during the later course than combined BS/IS. Scintigraphic errors due to ectopic, peripheral, haematopoietic bone marrow can be corrected by MRI.

Life-threatening spontaneous retroperitoneal bleeding: a rare complication of oral anticoagulation

In a patient on oral anticogulation with sudden onset of loin pain, the possibility of spontaneous bleeding in the retroperitoneum must be considered in the differential diagnosis of renal colic. This rare pathology can be life-threatening, and rapid diagnosis with ultrasound and computerized tomography of the abdomen must be made. If the patient is hemodynamically stable, a conservative approach is justified. Otherwise, emergency nephrectomy may be needed. As patients become older and indications for anticoagulant therapy become more common, we will probably have to face more of these rare bleeding complications in the future. We report such a case.