A-585 B. Peripheral skeleton
V.N. Cassar-Pullicino | Monday, March 11, 10:30 – 12:00 / Room A
In this interactive session focussing on peripheral musculoskeletal lesions presenting to the Accident and Emergency Department, we will review the strengths and weaknesses of the imaging modalities applied to chosen bone, joint and soft tissue lesions. The imaging-based approach will strengthen the understanding of the different pathological entities which vary from trauma to infection in both the paediatric and adult age groups.
A-618 C. Cystic fibrosis and other bronchiectatic diseases
M.U. Puderbach | Monday, March 11, 16:00 – 17:30 / Room I/K
Several different diseases go along with the development of bronchiectasis. Bronchiectasis may result from chronic infection, proximal airway obstruction, or congenital bronchial abnormality. In cystic fibrosis, bronchiectasis is one of the key features of lung involvement. Bronchiectasis can present with a variety of non-specific clinical symptoms, including hemoptysis, cough, and hypoxia. Bronchiectasis is defined as localized or diffuse irreversible dilatation of the cartilage-containing airways or bronchi. The imaging gold standard for bronchiectasis is thin-section CT. Morphologic criteria on thin-section CT scans include bronchial dilatation with respect to the accompanying pulmonary artery (signet ring sign), lack of tapering of bronchi, and identification of bronchi within 1 cm of the pleural surface. Bronchiectasis may be classified as cylindric, varicose, or cystic, depending on the appearance of the affected bronchi. It is often accompanied by bronchial wall thickening, mucoid impaction, and small-airways abnormalities. Besides CT, nowadays MRI of the lung is able to image the relevant morphological features of bronchiectasis. In addition, functional changes due to bronchiectasis can be studied.
A-187 A. RF ablation
J. del Cura | Friday, March 8, 16:00 – 17:30 / Room N/O
RF ablation is currently indicated in HCC as curative treatment in Child-Pugh A-B patients with: single <2 cm nodule and not candidates for transplation, 1-3 nodules <3 cm and not candidates for resection or transplantation. RF can be also performed in patients waiting for liver transplantation. Some studies suggest that survival does not differ between RF ablation and resection in 5 cm because of the high possibility of recurrence. Different types of electrodes can be used: internally cooled, cluster, expandable, with saline instillation. Although results can be good with any of them, every type of device requires a different technique of ablation. Obtaining a margin of at least 0.5 cm of ablated tissue around the tumour is key to avoid recurrences. Combined treatments like combining chemoembolization or PEI with RFA can be useful to increase the ablation volume. Published data show a pooled 5-year survival of 48-55%, with better outcomes in Child-Pugh A patients. In candidates for surgery, 5-year survival is similar to resection: 76 %. RFA is safe: major complications appear in 10 % and reported mortality is 0.15%. Tumours located subcapsular or near major vessels, biliary tree or bowel are more prone to complications. Laparoscopic ablation can be an alternative in these cases. Imaging follow‑up with CT, MRI or CEUS is performed to assess the outcome and detect recurrences, new lesions or complications. Although not well established, most protocols include an immediate post-procedure imaging, 1-month follow-up and explorations every 3 or 6 months for 2-3 years.
A-438 A. The current criteria for nodal involvement on CT/MRI
W. Schima | Sunday, March 10, 14:00 – 15:30 / Room E2
In a variety of diseases, such as metastatic disease, lymphoma and inflammation, lymph node enlargement can be seen. Thus, lymph node characterization is important to differentiate between benign and malignant disease. It is based on size (short axis diameter) and morphologic criteria, such as shape, homogeneity, and contrast enhancement. For abdominal nodes, location-specific size criteria apply (upper limit of normal: lower paraaortic 11 mm, upper paraaortic 9 mm, gastrohepatic ligament 8 mm, portocaval space 10 mm, retrocrural space 6 mm; pelvic nodes 10 mm). However, in clinical practice, often a universal size threshold of 10 mm is used in abdominal imaging. In chest CT, an upper limit of normal of 10 mm is universally applied. However, size criteria alone are unreliable: CT for lung cancer staging has a pooled sensitvity of 51 % (i.e., false negative diagnoses of metastatic deposits in normal-sized nodes), and a specificity of 86 % (i.e., false positive diagnoses due to enlarged reactive nodes). With MRI, the same size criteria apply. However, additionally features such as central necrosis (T2w fatsat or gadolinium-enhanced images) are suggestive of metastasis (or suppurative infection). Lymph node-specific USPIO MR agents can depict tumour deposits in subcentimeter pelvic nodes. Unfortunately, they did not reach market approval. DWI is helpful in identifying in lymph nodes as they exhibit high SI with higher b-values. However, diffusion pattern of benign and malignant nodes overlap, so that ADC values do not aid in characterization. Despite the use of modern MDCT and MRI techniques, lymph node characterization needs further improvement.
B-0801 Treatment response assessment in Hodgkin lymphoma: in search for morphological correlates of metabolic activity
T. Knogler, G. Karanikas, M. Weber, K. El-Rabadi, M.E. Mayerhoefer | Monday, March 11, 10:30 – 12:00 / Room F1
Purpose: To predict early treatment response with three-dimensional texture features (TF) in patients with Hodgkin lymphoma (HL) after radio-chemotherapy extracted from contrast-enhanced CT.
Methods and Materials: 21 patients with histologically proven HL were included in this study. Contrast-enhanced (18)F-FDG PET/CT was obtained on a dedicated PET/CT scanner. Volumes-of-interest and long- and short-axis diameter were manually defined on 48 HL manifestations prior and post-radio-chemotherapy on the CT image stack. Three-dimensional texture features derived from the grey-level histogram, co-occurrence matrix, run-length matrix and absolute gradient were calculated for the VOIs. A stepwise logistic regression with forward selection was performed to find classic radiologic features (i.e. lesion diameter, lesion volume) and TF, which correctly classify treatment response (i.e. full response and partial response). Classification in PET/CT was used as reference.
Results: Difference in short axis diameter best fit as classic feature with a sensitivity of 100 %, a specificity of 54,5% and an accuracy of 89,6%. Combination of “S_0_0_1_Entrp” and difference of “vertl_fraction” best fit as TF with a sensitivity of 97,3%, a specificity of 72,7% and an accuracy of 91,7%.
Conclusion: Texture features extracted from contrast-enhanced CT in patients with HL are superior in differentiation between responders and non-responders without the need for PET examinations, compared to classical radiological features. However, PET/CT as state-of-the-art imaging technique has a sensitivity and specificity >90%, so that further research with larger patient number is needed to investigate this new method.
A-445 Biliary procedures
M. Krokidis, A.A. Hatzidakis | Sunday, March 10, 14:00 – 15:30 / Room F1
Palliative Percutaneous Transhepatic Biliary Drainage (PTBD) is a therapeutic procedure leading to drainage of the obstructed bile duct system. If endoscopy is not possible and if patient is inoperable, then the percutaneous treatment is indicated. Drainage of the bile ducts is performed with a small plastic multiple hole pigtail catheter. Self-locking catheters are preferred in order to minimize the dislocation risk. The percutaneous catheter is pushed through the malignant stricture, so that bile is draining through the catheter towards the bowel loops. Technical success rate of percutaneous biliary drainage can reach nearly 100 % in experienced hands, while the major complications rate is usually lower than 5 %. Clinical efficacy is usually lower, but still over 90 %. The drainage procedure can be extended with the placement of a permanent metallic stent, which keeps the stenosed biliary duct patent, without need for a catheter. Metallic biliary stents have been proved as the best palliative treatment of non-resectable malignant obstructive jaundice, allowing longer patency rates than plastic endoprostheses. The technique is safe, with low-complication rate and procedure-related mortality between 0.8 and 3.4%. Still controversial remains in the timing between initial drainage and metallic stent placement, as well as the question of balloon dilatation before stent insertion. There is evidence that if the initial transhepatic drainage is completed without causing any severe complications, especially bleeding in form of haemobilia, primary metallic stenting can follow as a single-step procedure.
B-0829 Feasibility of abdominal diffusion Kurtosis imaging compared to standard diffusion weighted imaging at 1.5 and 3 Tesla
H. Haubenreisser, J. Hansmann, A. Lemke, J. Wambsganss, S.O. Schönberg, U. Attenberger | Monday, March 11, 10:30 – 12:00 / Room I/K
Purpose: To demonstrate the feasibility of diffusion kurtosis imaging (DKI) for the depiction and differentiation of liver and kidney abnormalities in comparison to standard diffusion weighted imaging (DWI) at 1.5 and 3 T.
Methods and Materials: 109 consecutive patients underwent a routine abdominal MR protocol including standard DWI and DKI. 1.5 and 3 T b-values for DKI were identical: b=0-100-500-1000-1500-2000 s/mm². 55 liver and 36 kidney lesions were evaluated at 1.5 T, and 16 liver and 11 kidney lesions, respectively, at 3 T. DKI was assessed by an in-house built software. Kurtosis values were quantified by region-of-interest analysis and compared between lesions and normal parenchyma by a Wilcoxon rank sum test.
Results: Mean kidney kurtosis values were identical at 1.5 and 3 T in normal parenchyma (K=0.5) and cysts (K=0.4). Differences dependent on field strength were only found in malignant tumours (0.8 vs 0.5). At 1.5 as well as 3 T, cysts, tumours and normal kidney parenchyma could be differentiated with significance (p<0.0413) using the kurtosis values. At both field strengths, cysts, benign and malignant liver tumours could be differentiated with statistical significance from normal parenchyma (p<0.001, p<0.0071, p<0.001). However, malignant and benign liver tumours were significantly different at 1.5 T (p=0.0382). Abnormalities and normal parenchyma could be visually differentiated on both, DWI and DKI.
Conclusion: DKI of kidney and liver abnormalities is feasible at both, 1.5 and 3 T and allows for a quantified differentiation between normal parenchyma and pathologic lesions.
B-0962 First experiences with a self-test for Dutch breast screening radiologists as a quality assurance tool
J. Timmers, A. Verbeek, R. Pijnappel, M. Broeders, G. den Heeten | Monday, March 11, 14:00 – 15:30 / Room F2
Purpose: To evaluate the use of a self-test as a quality assurance tool for screening radiologists in the Dutch breast cancer screening programme.
Methods and Materials: 144 screening radiologists were invited to voluntarily complete a test set of 60 screening mammograms. The following grading criteria were assigned regarding the most suspicious lesion: location, level of suspicion, BI-RADS, laterality, type (well defined mass, ill defined mass, spiculated mass, microcalcification clusters, architectural distortion and asymmetric density) and mammographic density are assigned. Also, several reader characteristics, such as years of experience and number of cases read per year, were to be completed. Case and lesion sensitivity and specificity were determined for all readers. The spearman correlation coefficient was used to determine correlation between reader characteristics and performance measured by the area under the receiver operator characteristics (ROC) curve (AUC).
Results: 112 radiologists completed the test set (78%). The mean age was 49 (range 33-68) and on radiologists read on average 10,000 (range 700-60,000) screening mammograms per year. The median AUC value was 0.91, case sensitivity 91 %, lesion sensitivity was 91 % and specificity 94 %. The AUC was not correlated to reader characteristics. The test-set revealed interobserver variation in assigning lesion types.
Conclusion: Overall, a good performance was seen among all screening radiologists. Readers are able to determine their educational needs and compare it with peers during training or audits. It is therefore a useful quality assurance tool. Medical education should be dedicated to reducing interobserver variation.
A-254 A. Plain radiography
J. Cáceres | Saturday, March 9, 10:30 – 12:00 / Room A
There are certain signs in the chest radiograph, which help in the identification and differential diagnosis of selected processes. Their appearance is characteristic enough to be identified. Some of them correspond to normal variants, which should not be confused with pathologic processes. In this presentation, we will describe several signs in chest imaging that, in our experience, have proven helpful to us in the diagnosis of chest pathology.
B-0931 Dynamic contrast-enhanced imaging for detection of complications after double-bundle reconstruction of the anterior cruciate ligament
Y.-C. Lin, Y.-H. Juan, Y.-C. Cheung, W.-L. Yeh, C.-H. Chiu, C.-F. Tan, C.-M. Kuo | Monday, March 11, 14:00 – 15:30 / Room E1
Purpose: Double-bundle reconstruction with stump preservation has revolutionized the surgical treatment for anterior cruciate ligament (ACL) injury. However, poor revascularization at the osteoligamentous interface (OI) of the tibia tunnel remains a major cause of graft complications. In this study, we applied dynamic contrast-enhanced (CE) magnetic resonance imaging (MRI) to quantify the OI enhancement values of the tibia tunnels and ACL stump. We aimed to determine the relationship between graft complications and OI and stump enhancements.
Methods and Materials: From October 2011 to April 2012, 34 patients were enrolled in our study (mean postoperative duration, 7.3 months). All patients underwent one 1.5-T MRI study with the imaging pulse-sequence protocol of proton density-weighted imaging (WI), T2WI, pre-enhanced and post-enhanced T1WI, and dynamic CE MRI. Graft complications, including cystic degeneration and tear, were evaluated using pre-enhanced MRI, and peak enhancement (ePeak) values were acquired from a dynamic CE study. The receiver operating characteristic (ROC) analysis was used to obtain optimal cut-off values for complicated grafts.
Results: Our study included 28 patients (mean age, 25.5 years). Nine patients (32.1%) had cystic degeneration and 1 (3.6%) had complete posterolateral (PL) bundle tear. Mean ePeak percentages for graft with or without complications were 84.19%/127.69% for anterior–medial (AM) bundle, 107.54%/128.21% for PL bundle, and 171%/151.06% for stump, respectively. ROC analysis yielded the optimal ePeak cut-off values of 126 %, 104 %, and 35 % for AM bundle, PL bundle, and stump, respectively.
Conclusion: Graft complications were directly associated with higher tibial OI values but inversely associated with higher stump values.