[Radiologic features of inflammatory pseudotumors]

Inflammatory pseudotumor is a rare benign tumor entity. Because inflammatory pseudotumors mimic malignant tumors both clinically and radiologically, the radiologist should be familiar with this entity. Inflammatory pseudotumor most commonly involves the lung and the orbit, but it has been reported to occur in nearly every site in the body. For making a definite diagnosis a biopsy is often essential. The treatment options are varied and consist of surgery, high-dose steroids, irradiation, and chemotherapeutics.

CT-Koronarangiographie bei Patienten mit Vorhofflimmern

PURPOSE

Reliable visualization of the coronary arteries with multislice spiral CT angiography (MSCTA) in patients with atrial fibrillation (AF) remains a challenge despite retrospective ECG gating. A recently developed new algorithm automatically compensates dynamic changes in the heart rate during the scan, thus reducing misregistration and motion artifacts. The HeartBeat-RT algorithm combines a fixed-percent delay determined from the first R wave and the fixed offset delay based on the second R wave in the ECG cycle. The purpose of this study was to find out the optimal reconstruction window in MSCTA in patients with AF for each of the three major coronary arteries during the cardiac cycle.

MATERIALS AND METHODS

20 patients with permanent AF were imaged on a 16-slice scanner (slice collimation: 16 x 0.75 mm; rotation time 0.42 s; 140 kV; 380 mAs; 120 ml Ultravist 370 (R) i.v.). The patients had not received any previous drugs for heart frequency regulation. Acquisition was started after bolus tracking of a biphasic bolus of 120 ml Ultravist 370 injected intravenously. Each coronary segment was reconstructed at 0 % - 90 % of the cardiac cycle in increments of 10 %. For image analysis we used coronary segments as defined by the American Heart Association. Two blinded independent readers assessed the image quality in terms of visibility and artifacts (five-point rating scale 1 = very poor, 2 = poor, 3 = fair, 4 = good and 5 = excellent) and the degree of stenosis (five-point rating scale 1 = 0 %, 2 = 1 % - 49 %, 3 = 50 % - 74 %, 4 = 75 % - 99 %, 5 = 100 %) on axial slices, multiplanar reconstructions and three-dimensional volume-rendered images.

RESULTS

The heart rate during examination ranged between 42 and 156 beats per minute, the average heart rate was 78 +/- 23. Each of the two readers evaluated 300 segments in 20 patients. Visualization of all coronary artery segments was superior at 40 % (mean score of the image quality 2.79) as compared to the standard diastolic reconstruction window at 80 % (image quality 2.33). The second best image quality (2.57) was acquired at 0 % of the cardiac cycle.

CONCLUSION

The use of a frequency adapted delay algorithm with the choice of an end-systolic reconstruction window provided diagnostically valuable images in patients with AF.

[Budd-Chiari syndrome in a patient with paroxysmal nocturnal haemoglobinuria]

HISTORY AND CLINICAL FINDINGS

A 61-year-old man with dyspnea and diffuse abdominal pain due to increasing ascites caused by liver cirrhosis of unknown etiology was admitted for consideration of transjugular intrahepatic portosystemic stent-shunting (TIPSS). The patient's medical history included paroxysmal nocturnal hemoglobinuria (PNH), presenting as slight hemolysis diagnosed 24 years previously. One year before the patient underwent radical retropubic prostatectomy for a localized prostate cancer. Shortly after this intervention he developed ascites.

INVESTIGATIONS

Color Doppler ultrasonography revealed an abnormal flow in the major hepatic veins. Transjugular liver biopsy indicated hepatic a circulatory disorder. Hepatic venography revealed the so-called "spider web" pattern characteristic for the Budd-Chiari syndrome. The hypercoagulable state due to paroxysmal nocturnal hemoglobinuria was accentuated by manipulation on the prostate during prostatectomy and presumably resulted in a thrombotic obstruction of the hepatic veins.

TREATMENT AND CLINICAL COURSE

After exclusion of contraindications a transjugular intrahepatic portosystemic stent shunt (TIPSS) was performed, which led to a decrease of portal pressure. Signs of portal hypertension such as esophageal varices and ascites resolved completely. The patient has been free of complaints for one year.

CONCLUSION

We assume that a hypercoagulopathy due to asymptomatic paroxysmal nocturnal hemoglobinuria resulted in Budd-Chiari syndrome when boosted by postoperative release of procoagulation factors in the thrombokinase-rich prostate. TIPSS is a therapeutic option in these patients.

PET-CT in der Nachsorge des kolorektalen Karzinoms: Einfluss der Bildfusion auf die Staginggenauigkeit

PURPOSE

To evaluate the diagnostic impact of positron emission tomography (PET) with fluorine-18-labeled deoxy-D-glucose (FDG) combined with non-contrast computed tomography (CT) as PET-CT modality in restaging colorectal cancer patients.

MATERIAL AND METHODS

In this retrospective study, 29 consecutive patients with histologically proven colorectal cancer (17 female, 12 male, aged 51-76 years) underwent whole body scans in one session on a dual modality PET-CT system (Siemens Biograph) 90 min. after i.v. administration of 370 MBq 18F-FDG. The CT imaging was performed with 40 mAs, 130 kV, slice-thickness 5 mm and without i.v. contrast administration. PET and CT images were reconstructed with a slice-thickness of 5 mm in coronal, sagittal and transverse planes. During a first step of analysis, PET and CT images were scored blinded and independently by a group of two nuclear medicine physicians and a group of two radiologists, respectively. For this purpose, a five-point-scale was used. The second step of data-analysis consisted of a consensus reading by both groups. During the consensus reading, first a virtual (meaning mental) fusion of PET and CT images and afterwards the "real" fusion (meaning coregistered) PET-CT images were also scored with the same scale. The imaging results were compared with histopathology findings and the course of disease during further follow-up.

RESULTS

The total number of malignant lesions detected with the combined PET/CT were 86. For FDG-PET alone it was n = 68, and for CT alone n = 65. Comparing PET-CT and PET, concordance was found in 81 of 104 lesions. Discrepancies predominantly occurred in the lung, where PET alone often showed true positive results in lymph nodes and soft tissue masses, where CT often was false negative. Comparing mental fusion and "real" co-registered images, concordance was found in 94 of 104 lesions. In 13 lesions or, respectively, in 7 of 29 patients, a relevant information was gathered using fused images.

CONCLUSION

Combined PET/CT leads to greater accuracy in the interpretation of data and is a valuable tool for diagnosis and anatomic localization of metastases in colorectal cancer patients.

Wert der Applikation von Nitroglycerin bei der 3D-MR-Koronarangiographie mit Echtzeit-Navigatortechnik

PURPOSE

Nitroglycerin administration results in dilation of epicardial coronary vessels and in an increase in coronary blood flow, and has been suggested to improve MR coronary angiography. This study evaluates systematically whether administration of nitroglycerin improves the visualization of coronary arteries and, as a result, the detection of coronary artery stenosis during free breathing 3D coronary MR angiography.

MATERIALS AND METHODS

Coronary MR angiography was performed in 44 patients with suspected coronary artery disease at a 1.5 Tesla System (Intera, Philips Medical Systems) (a) with and (b) without continuous administration of intravenous nitroglycerin at a dose rate of 2.5 mg/h, using an ECG gated gradient echo sequence with real-time navigator correction (turbo field echo, in-plane resolution 0.70 x 0.79 mm(2), acquisition window 80 ms). Equivalent segments of the coronary arteries in the sequences with and without nitroglycerin were evaluated for visualized vessel length and diameter, qualitative assessment of visualization using a four point grading scale and detection of stenoses > 50 %. Catheter coronary angiography was used as a gold-standard.

RESULTS

No significant differences were found between scans with and without nitroglycerin as to average length of the contiguously visualized vessel length (p > 0.05) and diameter (p > 0.05). There was also no significant difference in the coronary MR angiography with and without nitroglycerin in the average qualitative assessment score of the visualization of LM, proximal LAD, proximal CX, and proximal and distal RCA (2.1 +/- 0.8 and 2.2 +/- 0.7; p > 0.05). Sensitivity (77 % [17/22] vs. 82 % [18/22] p > 0.05) and specificity (72 % [13/18] vs. 72 % [13/18] p > 0.05) for the detection of coronary artery stenosis also did not differ significantly between scans with and without intravenous administration of nitroglycerin.

CONCLUSION

Administration of nitroglycerin does not improve visualization of the coronary arteries and detection of coronary artery stenosis in free breathing 3D coronary MR angiography.

[Diagnostic imaging of vascular leiomyosarcomas]

Primary vascular leiomyosarcomas are very rare tumors, with the venous variety most often arising from the inferior caval vein and the arterial variety from the pulmonary artery. The tumors show either an exclusive intra- or extravascular pattern or a mixed growth pattern. The clinical symptoms depend on tumor location, with intraluminal tumors of the inferior caval vein causing edema or a Budd-Chiari syndrome. Leiomyosarcomas of the pulmonary artery can mimic chronic central or recurrent peripheral pulmonary embolism. Contrast enhanced spiral CT with multiplanar reconstruction is the diagnostic method of choice when a vascular leiomyosarcoma is suspected. MRI with MR-angiography can be added. If a tumor of undetermined origin shows a broad contact with a vessel and/or an intraluminal component, possible primary vascular leiomyosarcoma should be included in the differential diagnosis.

Perfusion and molecular diffusion-weighted MR imaging of the brain: in vivo assessment of tissue alteration in cerebral ischemia

The combined use of perfusion imaging (PI) and diffusion-weighted imaging (DWI) is opening a new window into the processes that occur during the first hours of ischemia. DWI detects changes in molecular diffusion associated with cytotoxic edema. PI characterizes the degree of regional hypoperfusion. Regions showing mismatches between DWI and PI, i.e. hypoperfused areas with normal diffusion behavior are considered potentially salvageable. We present results of 11 patients with an occlusion of the middle cerebral artery stem and spontaneous stroke evolution. Whereas the infarct was clearly visible on initial DWI and PI, surrounding tissue at risk of infarction was marked in all patients by an increased blood volume and transit time, but only in a subgroup (n = 3) where alteration were more pronounced this tissue at risk was progressively infarcted. These human DWI and PI data show alterations in the area of tissue at risk which correlates with infarct progression.

In-vivo proton MR-spectroscopy of the human brain: assessment of N-acetylaspartate (NAA) reduction as a marker for neurodegeneration

Proton magnetic resonance spectroscopy ((1)H-MRS) is a non-invasive method to investigate changes in brain metabolite composition in different cerebral diseases. We performed proton spectroscopy in patients with dementia of the Alzheimer's type (AD) and in patients with motor neuron disease (MND) with the aim to detect the specific metabolic pattern for these neurodegenerative disorders. In the MND group we found a significant reduction of NAA/tCr metabolite ratios in the motor cortex, which correlates with the disease severity and the clinical lateralization of neurological symptoms and further decreases in the time course of the disease. In AD patients a reduction of NAA/tCr was observed in the medial temporal lobe. Since NAA is exclusively expressed in neurons as shown by immunohistochemical studies, reduced NAA levels suggest neuronal loss or dysfunction in the observed regions. The observed regional metabolic alterations reflect the neuronal basis of the characteristic neurological symptoms in AD (dementia) and MND (muscular palsy) and mirrors the disease progress over time.

Three-dimensional magnetic resonance cholangiopancreatography with respiratory triggering in the diagnosis of primary sclerosing cholangitis: comparison with endoscopic retrograde cholangiography

BACKGROUND AND STUDY AIMS

The purpose of this study was to evaluate the accuracy of respiratory-triggered three-dimensional magnetic resonance cholangiopancreatography (3D-MRCP) for the detection of primary sclerosing cholangitis (PSC) and to compare the specific findings of magnetic resonance cholangiography and endoscopic retrograde cholangiography in patients with PSC.

PATIENTS AND METHODS

The MRCP findings were evaluated in 150 patients with clinical symptoms (progressive fatigue, pruritus followed by icterus) and/or elevated values for alkaline phosphatase and serum aspartate transaminase, and occasionally an elevated serum concentration of bilirubin as a sign of cholestasis, who were consecutively referred for magnetic resonance imaging. Two observers independently classified bile duct abnormalities and established the MRCP diagnosis in a consensus reading. The results of MRCP were compared with the definitive diagnosis, which was based on the clinical history and laboratory and histological data, as well as on endoscopic retrograde cholangio-pancreatography (ERCP) findings. In a second step, the observers compared the delineation of the biliary system and morphological findings using MRCP and ERCP in patients with confirmed PSC.

RESULTS

Diagnostic examinations were obtained in 146 of the 150 MRCPs (97 %). The diagnosis of PSC was confirmed by clinical data and ERCP in 34 of these 150 patients (23 %). The sensitivity and specificity of MRCP for diagnosing PSC were 88 % (29 of 33) and 99 % (108 of 109), respectively. MRCP and ERCP yielded similar scores for the delineation of the biliary system (P = 0.2) in patients with PSC. However, different bile duct abnormalities leading to the diagnosis of PSC were depicted by MRCP and ERCP; more bile duct stenoses and pruning were seen with ERCP and more skip dilatation with MRCP (P < 10(-4)).

CONCLUSION

In patients with PSC, MRCP is a highly sensitive method and its diagnostic accuracy is comparable to that of ERCP.