B-0789 CT colonography: accurate registration of prone and supine endoluminal surfaces of the colon
T.E. Hampshire, H.R. Roth, E. Helbren, A. Plumb, D. Boone, G. Slabaugh, S. Halligan, D.J. Hawkes | Monday, March 11, 10:30 – 12:00 / Room E2
Purpose: Computed tomographic (CT) colonography is a technique for detecting bowel cancer or potentially precancerous polyps. Because retained fluid and stool can mimic pathology, CT data are acquired with the patient in both prone and supine positions. Radiologists then match endoluminal locations between the two acquisitions to determine whether pathology is real. This process is hindered by the fact that the colon can undergo large deformations that often occur during repositioning of the patient. Automated registration between datasets could potentially improve efficiency and diagnostic accuracy.
Methods and Materials: We have developed software to establish correspondence between prone and supine endoluminal surfaces. An initialisation step generates image patches at the positions of haustral folds using depth map renderings and is optimised by virtual camera registration. Additional neighbourhood information is then included in a Markov Random Field model to establish landmark-based correspondences. Subsequently, the complexity of the registration task is reduced by mapping both prone and supine surfaces onto a cylindrical domain in which correspondence is established using non-rigid image registration.
Results: The registration was applied to 17 CTC cases including cases exhibiting luminal collapse, achieving fold matching accuracy of 96 %. Providing an accurate initialisation, the method significantly improved the cylindrical registration (p<0.001), achieving a mean error of 6.0mm measured at 1743 reference points.
Conclusion: The proposed method can successfully establish correspondence between prone-supine locations on the endoluminal surface derived from CT colonography. The ability to rapidly and automatically match polyps between acquisitions will facilitate CT colonography interpretation.
B-0680 Texture analysis of malignant breast tumours: is a differentiation of ductal carcinoma in situ, invasive ductal and invasive lobular breast cancer possible?
T. Knogler, K. Pinker-Domenig, N. Perry, S. Milner, K. Mokbel, M.E. Mayerhoefer | Sunday, March 10, 10:30 – 12:00 / Room F2
Purpose: To evaluate the ability of texture features (TF), to differentiate between ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) of the breast on full-field digital mammograms (FFDM).
Methods and Materials: 110 screen detected and histopathologically verified breast cancers (27 DCIS, 73 IDC, 10 ILC) imaged with FFDM in standard views were included in this study. For each lesion, a region of interest (ROI) was manually defined, which covered the lesion as well as a rim (1cm width) of normal-appearing breast tissue around the lesion in the view, where the lesion was depicted in largest diameter. TF derived from the grey-level histogram, co-occurrence matrix (COC), run-length matrix (RLM), absolute gradient (AG), autoregressive model (ARM) and wavelet transform were calculated for the ROIs. Fisher coefficients were calculated to determine which TF were best-suited for distinguishing between DCIS, IDC and ILC. Lesion classification was performed using linear discriminant analysis in conjunction with a k-nearest neighbour classifier, based on the combination of the 10 TF with the highest Fisher coefficients. Classification accuracy was used as the primary outcome measure.
Results: The accuracy of texture-based lesion classification was 84.33% (70 of 83 lesions) for IDC vs. ILC, 81.1% (30 of 37 lesions) for ILC vs. DCIS, but only of 70 % (70 of 100 lesions) for IDC vs. DCIS.
Conclusion: TF derived from FFDM may be of value for differentiating between ILC and IDC, and ILC and DCIS, but of limited value for differentiating between IDC and DCIS.
A-162 Upper limb nerve entrapment
D. Weishaupt | Friday, March 8, 16:00 – 17:30 / Room E1
The peripheral nerves of the upper limb are affected by a number of entrapment and compression neuropathies. These syndromes involve the brachial plexus as well as the musculocutaneous, axillary, suprascapular, ulnar, radial and median nerves. Clinical examination and electrophysiological studies are traditionally the mainstay of diagnostic work-up. However, ultrasonography and magentic resononance imaging (MRI) may provide key information about the exact anatomic location of the lesion or may help to narrow the differential diagnosis. In certain patients with the diagnosis of a peripheral neuropathy, imaging using either ultrasononography of MRI may help establish the cause of the condition and provide information crucial for conservative management or surgical planning. In addition, imaging is particularly valuable in compex cases with discrepant nerve functions test results.
A-495 Imaging of the most frequent emergencies of the genitourinary tract
L.E. Derchi | Sunday, March 10, 16:00 – 17:30 / Room E1
This presentation will deal with three of the most common and important acute problems of the GU system: testicular and ovarian torsion and the renal colic. US is the technique of choice in patients with acute scrotum and is able to identify torsion in up to 86 % – 94 % of cases. Tips and tricks to improve diagnostic accuracy and recognize possible false negatives will be presented. Difficulties can be encountered also in identifying ovarian torsion, and the role of US, CT and MRI in this field will be addressed, stressing the need for accurate correlation of clinical and radiological findings to reach the correct diagnosis. MDCT is the gold standard examination in patients with suspected renal colics, being able to recognize presence, location and size of the obstructing stone(s) in virtually all cases, or to identify other pathologic conditions which are responsible for the patient’s symptoms. However, stone disease is frequent, recurrent and often affects patients of relatively young age; then, radiation exposure concerns have to be taken into account. Protocols using US as the first approach can solve up to 75 % of cases, reserving MDCT only for those which are undetermined after US. The US examination techniques to be used in these situations will be addressed.
A-425 Scrotal tumours
P.S. Sidhu | Sunday, March 10, 14:00 – 15:30 / Room C
Ultrasound remains the imaging modality of choice for the assessment of any form of scrotal pathology. The resolution capabilities of the technique and the superficial nature of the scrotal contents allow ultrasound examination to deliver optimal imaging. Testicular tumours maybe imaged and characterised with ease, without need for further imaging techniques. The addition of colour Doppler ultrasound allows for the interrogation of the vascularity of any lesion seen, and the addition of newer techniques such as contrast-enhanced ultrasound and tissue elastography has beneficial effects to aid interpretation and diagnosis. Nearly all focal abnormalities of the testis in the adult patient are malignant lesions, with primary germ cell tumours a frequent abnormality in the younger patient, and lymphoma or a secondary malignancy common in the older patient. However, benign abnormalities such as a focal infarction, haematoma or an epidermoid cyst may mimic malignancy. It is important to be able differentiate benign from malignant causes, with testis sparing the ultimate goal. Non-germ cell tumours present a specific conundrum, with the newer imaging techniques likely to be of benefit in distinguishing these tumours from germ cell tumours. Extra-testicular tumours are nearly always benign and include lipoma and adenomatoid lesions. Inflammatory disease may also simulate a tumour and presents an unexpected pitfall. A carful scrotal ultrasound examination, using all the available ultrasound techniques should allow the examiner to make a confident assessment of any scrotal tumour, and allow for the correct management without need for further imaging.
B-0959 Breast cancer prediction modelling based on common mammographic findings in screening
J. Timmers, A.L.M. Verbeek, R.M. Pijnappel, J. in ‘t Hout, M.J.M. Broeders, G.J. den Heeten | Monday, March 11, 14:00 – 15:30 / Room F2
Purpose: To develop a prediction model for breast cancer (nomogram) based on common mammographic findings on screening mammograms. The model is designed to reduce interobserver variation in assigning BI-RADS in the Dutch breast cancer screening programme.
Methods and Materials: We retrospectively reviewed 352 positive (digital) screening mammograms of women participating in the Nijmegen region of the Dutch screening programme (December 2006-November 2008). The following mammographic findings were assessed by consensus reading of 3 expert radiologists: masses and features of masses, calcifications, parenchymal deformity, asymmetric density and mammographic density and BI-RADS. Data on age, diagnostic work-up, final diagnosis and surgical procedures were collected from patient records. Multivariable logistic regression analyses were used to build our breast cancer prediction model, presented as a nomogram.
Results: Breast cancer was diagnosed in 108 cases (31%). The highest positive predictive value (PPV) was reported for spiculated masses (96%) and the lowest for well-defined masses (9%). Characteristics included in the nomogram based on statistical significance and clinical relevance are: age, mass, calcifications, parenchymal deformity and asymmetric density.
Conclusion: With our nomogram we developed a tool to assist screening radiologists in determining the chance of malignancy based on mammographic findings. We propose cut-off values for assigning BI-RADS categories in the Dutch screening setting based on our nomogram which will need to be validated in future research. These values can easily be adapted for use in other screening programmes.
B-0158 Initial clinical results of simultaneous PET/MRI in comparison with PET/CT in patients with head and neck cancer
P. Stumpp, K. Kubiessa, S. Purz, M. Gawlitza, A. Kühn, K.G. Steinhoff, A. Boehm, R. Kluge, T. Kahn | Thursday, March 7, 14:00 – 15:30 / Room C
Purpose: Describing diagnostic capability of simultaneous PET/MRI in comparison with PET/CT and their single components CT, MRI and PET in an initial prospective study based on 17 patients with head-and-neck cancer.
Methods and Materials: 17 patients with head-and-neck cancer received an 18F-FDG-PET/CT for staging or follow-up and an additional simultaneous PET/MRI scan with a whole body imaging part and a dedicated examination of the neck. Sole MRI, CT and PET components of the multimodal acquisitions plus the PET/MRI and PET/CT examinations were evaluated independently, blinded and in a randomised order by two readers. Results were compared with the reference standard, and sensitivity, specificity, positive (PPV) and negative predictive value (NPV) were calculated.
Results: 23 malignant tumours and 55 benign changes were found with the reference standard. For PET/CT the two reader groups showed a sensitivity of 78.3% and 87 %, a specificity of 85.5% and 89.1%, a PPV of 71.4% and 75 % and a NPV of 90.7% and 94 %. For PET/MRI sensitivity was 78.3% and 82.6%, specificity 81.8% and 94.5%, PPV 65.5% and 85.7% and NPV 91.2% and 93.8%. Evaluation of the single PET part from PET/CT revealed highest sensitivity of 95.7%, whereas evaluation of the sole MRI component from PET/MRI showed best specificity of 96.4%. There was a high interrater agreement in all modalities (Cohen’s kappa coefficient: 0.61 – 0.82).
Conclusion: PET/MRI of patients with head and neck cancer yielded good diagnostic capability, similar to PET/CT. Further studies on larger cohorts to prove these first results seem justified.
B-0012 Language impairment and reduced structural connectivity in Rolandic epilepsy
R. Besseling, J. Jansen, W.H. Backes | Thursday, March 7, 10:30 – 12:00 / Room C
Purpose: Rolandic epilepsy (RE) is a childhood epilepsy with mild seizure semiology and epileptic discharges originating from the sensorimotor (Rolandic) area. A serious co-morbidity in RE is language impairment, for which we aim to find a correlate using structural connectivity.
Methods and Materials: Diffusion MRI was performed at 3.0 Tesla and 2×2×2 mm voxel size with b=1200 s/mm2 and 66 diffusion gradient directions in 23 children with RE with proven language deficits and 23 matched controls. Constrained spherical deconvolution provided voxel-wise tract orientations and whole-brain tractography (5M streamlines). For each of the 4 Rolandic areas (bilateral pre- and postcentral gyri), the streamlines to any of the 70 regions, obtained by automatic cortical parcellation (Freesurfer), were selected from the whole-brain tractogram. For reliable connections (top 20 % of number of streamlines), connectivity was quantified by tract fractional anisotropy (FA), compared between groups, and correlated to language scores.
Results: In the left hemisphere, reduced tract FA was found for connections between the Rolandic areas and inferior frontal gyrus (Broca’s area) and supramarginal gyrus (Wernicke’s area), but not for contralateral homologue regions. For the aberrant connection between the left postcentral and inferior frontal gyrus, tract FA decreased with languages score in the RE group (p=0.04).
Conclusion: In RE structural connectivity between Rolandic and language areas is disturbed and correlates with the language dysfunction. This provides a neuronal link between the location of the epileptic discharges and the language impairment. This research was supported by the Dutch Epilepsy Foundation.
A-117 Pitfalls in neck imaging
F.A. Pameijer | Friday, March 8, 10:30 – 12:00 / Room C
Pitfall: “a hidden or unexpected danger or difficulty”. Imaging methods can provide an extraordinary amount of useful data to specialists treating head and neck (cancer) patients. It is crucial that these data are used to full advantage of individual patients. The most important factor in this process is mutual cooperation between the physicians in charge of patient care and the diagnostic imaging specialist. Pitfalls in the head and neck may present in various ways: normal variants may look like disease, incidental findings are frequently encountered, suboptimal technique may obscure important findings. Moreover, many pitfalls are directly related to technical errors. In this potential ‘minefield’, the post-treatment patient presents a major challenge to the imaging specialist. Ablative surgery usually results in distortion of the anatomy, especially when combined with flap reconstruction. When adequate preoperative and/or baseline postoperative imaging is lacking, determination of recurrence on a single postoperative examination may well be impossible. PET CT (MR) and advanced MR-techniques; e.g. Diffusion Weighted Imaging (DWI) or Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) can be helpful in this setting. The presentation aims to familiarize general radiologists, who have an interest in head and neck imaging, with common pitfalls encountered on CT and MR studies focussing on the neck. Both the pre-therapeutic, as well as the post-treatment setting, will be discussed using examples from daily practice.
B-0786 Evaluation of a new method for the assessment of anterior acetabular coverage and hip joint space narrowing
R. Ferré, E. Gibon, A. Feydy, H. Guerini, R. Campana, N. Zee, C. Bourdet, M. Hammadouche, J.-l. Drapé | Monday, March 11, 10:30 – 12:00 / Room E1
Purpose: The Lequesne’s false profile (LFP) view is commonly used to evaluate hip joint space narrowing (JSN) and anterior acetabular coverage using the vertical-center-anterior margin (VCA) angle. A novel low-dose biplanar slot scanner (SS) allows simultaneous acquisitions of weight-bearing oblique views of both hip joints. The aim was to compare LFP views versus biplanar oblique views obtained by SS.
Methods and Materials: LFP views were obtained on 56 hips on a computed radiography system. On the same hips, simultaneous oblique views of both hips were acquired in the SS, with the patient’s pelvis positioned at 45° from each acquisition plane. Two independent observers measured VCA angle and JSN on each acquisition. JSN was evaluated through the joint space/femoral head diameter ratio. Measurements from both techniques were compared using the student t-test and the Pearson’s correlation coefficient. Interobserver agreement of VCA angle and JSN assessments were calculated with the intraclass correlation coefficient (ICC).
Results: VCA angle was 33.5° (SD = 6.2°) with SS and 35° (5.6°) with LFP views (p<0.05). Pearson correlation coefficient between two techniques was 0.78 (p<0.01). JSN was 0,114 (SD = 0.03°) with SS and 0.108 (SD = 0.03°) with LFP views (p<0.05). Pearson correlation coefficient was 0.85 (p<0.01). ICCs for VCA angle were 0.91 with SS and 0.69 with LFP views. ICCs for JSN evaluation were 0.76 for both SS and LFP views.
Conclusion: SS is a reliable, easy, and low-dose evaluation of JSN and VCA angle despite a slight angular positioning compared with LFP.