1 12/9/2008 Page 1 Master s Program in Medical Physics Physics of Imaging Systems Basic Principles of Computer Tomography (CT) III Chair in Faculty of Medicine Mannheim University of Heidelberg Theodor-Kutzer-Ufer 1-3 D-68167 Mannheim, Germany Lothar.Schad@MedMa.Uni-Heidelberg.de www.ma.uni-heidelberg.de/inst/cbtm/ckm/ 12/9/2008 Page 2 Applications Applications Seite 1
2 12/9/2008 Page 3 Bones and Lung - high black/white contrast 12/9/2008 Page 4 Superior Vena Cava Thrombosis 130 kv, 150 ma, 0.8 s 5 mm, Pitch 1.5, 50% overlap - Siemens Emotion Seite 2
3 12/9/2008 Page 5 Liver Hemangioma Study 4 - phase spiral study excellent enhancement precontrast arterial portal-venous delayed phase 8 mm, Pitch 1.5 130 kv, 120 ma, 1.5 s 120 ml / flow rate 3 ml/s - Siemens Esprit 12/9/2008 Page 6 Ankle Joint: 1 mm Spiral CT Siemens Emotion: sagittal reformat Siemens Volume Access: VRT Seite 3
4 12/9/2008 Page 7 Spine 2 mm, Pitch 2 low dose ( 90 ma) low dose of 100 mas 2 x 1.5 mm collimation 2 mm slice width 99 s spiral duration Siemens Emotion / Emotion Duo 12/9/2008 Page 8 Pediatrics Head 2 x 1 mm, 60 mas 1.25 mm axial slice Siemens Emotion Duo Seite 4
5 12/9/2008 Page 9 Dental CT: Clinical Option life size filming semi-automatic evaluation for the jaws and teeth presurgical planning for implants 12/9/2008 Page 10 Brain: Cerebral Infarction I CT MRI Seite 5
6 12/9/2008 Page 11 Brain: Cerebral Infarction II 12/9/2008 Page 12 Osteoporosis: Bone Density Evaluation measurement of bone mineral density (BMD) for: early detection diagnosis follow-up of osteoporosis management of: metabolic bone diseases fractures in aging patients - CT accuracy of 10% is required due to individual variation of about 30% - but CT reproducibility of better than 2% is necessary in follow-up studies! Seite 6
7 12/9/2008 Page 13 Pulmonary CT: Lung Density Evaluation assessment of pulmonary structure & function emphysema cystic fibrosis clinical evaluation of new therapeutic approaches lung volume reduction surgery (LVRS) pharmaceutical treatment research & therapy in respiratory care (ICU) 12/9/2008 Page 14 Virtual Coloscopy source: Aurich and Beck. Institut für Informatik der Heinrich-Heine-Universität Düsseldorf, http://www.eccet.de/sample/colon.html#top Seite 7
8 12/9/2008 Page 15 CT Angiography CT Angiography 12/9/2008 Page 16 Cerebral Arteries 1 mm, Pitch 2 Siemens Emotion 2 x 0.5 mm, Pitch 3 Siemens Volume Zoom Seite 8
9 12/9/2008 Page 17 Carotids 130 kv, 100 ma, 0.8 s, 2 mm, Pitch 2 2 x 1 mm, Pitch 3, 1.25 mm SW Siemens Emotion / Emotion Duo 12/9/2008 Page 18 Abdominal Aortic Stent Follow-up 35 cm 130 kv, 143 mas, 0.8 s, 2 x 1.5 mm, Pitch 4 Siemens Emotion Duo Seite 9
10 12/9/2008 Page 19 Kidney CTA 12/9/2008 Page 20 Lung CTA Seite 10
11 12/9/2008 Page 21 CT Contrast Agent CT Contrast Agent 12/9/2008 Page 22 Contrast Study Challenges - catching the bolus at the right moment HU single slice: 40 s multislice: 5 s time (s) Seite 11
12 12/9/2008 Page 23 CARE Bolus - Automatic Bolus Tracking pre-monitoring reference scan start injection monitoring scans spiral scan patient individual start of the spiral scan 12/9/2008 Page 24 Perfusion CT: ROI Evaluation 1 2 time density curve Seite 12
13 12/9/2008 Page 25 Perfusion CT: Time to Peak Map 40 s 5 s 12/9/2008 Page 26 Early Stroke Diagnosis native CT perfusion (CBF) time - to - peak Seite 13
14 12/9/2008 Page 27 Perfusion CT: Follow-up I 62 years old women, 0.7 h after beginning of symptoms, hemiparesis left 40 sec 5 sec 12/9/2008 Page 28 Perfusion CT: Follow-up II 66 years old women, 1.2 h after beginning of symptoms, hemiparesis right 40 s 5 s Seite 14
15 12/9/2008 Page 29 Perfusion CT: Follow-up III 68 years old women, 2 h and 1 day after beginning of symptoms, hemiparesis left 40 sec 0. day (2.0 h) 0. day 2 h 1. day 19 h 5 sec 12/9/2008 Page 30 CT Cardio Imaging CT Cardio Imaging Seite 15
16 12/9/2008 Page 31 Cardio CT prospective triggering sequence scans in a single heart phase - quantification of coronary calcification - motion free images of thorax - imaging of large pulmonary vessels retrospective gating spiral acquisition and ECG-recording parallel reconstruction of imaging data at different heart phases possible not sensitive to cardiac arrhythmia since retrospective fitting of imaging data to the ECG-curve high resolution coronary CTA imaging of bypass-transplants quantification of coronary calcification at high reproducibility 12/9/2008 Page 32 Cardio CT: Retrospective Gating I projection angle θ z r z ECG time Seite 16
17 12/9/2008 Page 33 Cardio CT: Retrospective Gating II - single source CT: temporal resolution of maximum 165 ms temp. resolution = rotation time 2 = 165 ms courtesy: Siemens Medical Solution, Erlangen 12/9/2008 Page 34 Cardio CT: Retrospective Gating III - single source CT: technical challenge with high heart rates 60 bpm 100 bpm courtesy: Siemens Medical Solution, Erlangen Seite 17
18 12/9/2008 Page 35 Cardio CT: Multi Segment Reconstruction (a) 1 segment (half-scan reconstruction > 200 ms) (b) 4 segments (c) 2 segments (d) 3 segments source: Blobel et al. Fortschr Röntgenstr 2003 12/9/2008 Page 36 Cardio CT: Retrospective Gating IV - single source CT: multi-segment reconstruction 1 2 coronary arteries change position = limited image quality temp. resolution = (2 segment recon) varies between = 83 and 165 ms courtesy: Siemens Medical Solution, Erlangen Seite 18
19 12/9/2008 Page 37 Cardio CT: 3D Reconstruction heart beat = 70 b/min heart beat = 85 b/min heart beat = 100-110 b/min 12/9/2008 Page 38 Cardio CT: Stent 3D reconstruction of heart and coronary vessels using four-slice multi-slice CT. Note the stent in the proximal part of the left anterior descending artery cardiac vessel analysis of the stented segment in the same patient (Courtesy of Central Bank Medical Center, Moscow) source: ECR Newsletter 4/2002 Seite 19
20 12/9/2008 Page 39 Cardio CT: Coronal Angiography source: Kalender. Computertomographie, Publicis MCD Verlag 2000 12/9/2008 Page 40 Cardio CT: Heart Function (Pig) ~ 70 ms - retrospective ECG gating Seite 20
21 12/9/2008 Page 41 Dual Source CT Dual Source CT 12/9/2008 Page 42 Dual Source CT: Principle I alternative: rotating detector ring X-ray source stationary detector ring tube 1 gantry window fieldof-view X-ray fan tube 2 detector 2 detector 1 design of using multiple X-ray tubes with corresponding detectors has been proposed in the early years of CT to reduce scan time and increase temporal resolution (adapted according to Boyd, 1981). source: Kalender. Computertomographie, Publicis MCD Verlag 2000 Seite 21
22 12/9/2008 Page 43 Dual Source CT: Principle II - dual source CT: two X-ray sources and two detectors at the same time 0.33 seconds rotation courtesy: Siemens Medical Solution, Erlangen 12/9/2008 Page 44 Dual Source CT: Results I pulmonary embolism (arrow) pulmonary embolism (arrow) source: www.siemens.com/medical 04.2007 large aneurysm of ascending aorta triple rule-out examination with artifact-free visualization of right and left coronary arteries and aortic arch Seite 22
23 12/9/2008 Page 45 Dual Source CT: Temporal Resolution - dual source CT: heart rate independent temporal resolution of 83 ms temp. resolution = rotation time 4 = 83 ms courtesy: Siemens Medical Solution, Erlangen 12/9/2008 Page 46 Dual Source CT: Retrospective Gating - dual source CT: reliable imaging of all heart rates 60 bpm 100 bpm courtesy: Siemens Medical Solution, Erlangen Seite 23
24 12/9/2008 Page 47 Dual Source CT: Results II - dual source CT: patient with varying heart rate between 86 bpm and 122 bpm heart rate independent temporal resolution of 83 ms single source CT single source CT + multi segment recon. dual source CT courtesy: University Medical Center Grosshadern, Munich 12/9/2008 Page 48 Dual Source CT: Results III - dual source CT: precise RCA and LAD in stent visualization with reduced blooming and without motion artifacts - heart rate independent - temporal resolution: 83 ms - spatial resolution: 0.33 mm - 5 s for 103 mm - rotation: 0.33 sec - 120 kv, 400 mas/rotation - heart rate: 73 bpm courtesy: Erasmus MC, University Medical Center Rotterdam, The Netherlands Seite 24
25 12/9/2008 Page 49 Dual Source CT: Results IV - dual source CT: despite high heart rate of 90 bmp, motion free visualization of the coronary arteries - heart rate independent - temporal resolution: 83 ms - spatial resolution: 0.33 mm - 6 s for 138 mm - rotation: 0.33 sec - 120 kv, 400 mas/rotation - heart rate: 90 bpm courtesy: Nagoya City University Hospital, Nagoya, Japan 12/9/2008 Page 50 Dual Source CT: Results V - dual source CT: despite high heart rate of 122 bmp, motion free visualization of even small coronary arteries - heart rate independent - temporal resolution: 83 ms - spatial resolution: 0.33 mm - 6 s for 125 mm - rotation: 0.33 sec - 120 kv, 380 mas/rotation - heart rate: 122 bpm courtesy: University Hospital of Munich Grosshadern, Munich Seite 25
26 12/9/2008 Page 51 Dual Source CT: Results VI - dual source CT: quick and accurate rule out of myocardial infarction, pulmonary embolism, and aortic dissection - heart rate independent - temporal resolution: 83 ms - spatial resolution: 0.33 mm - 17 s for 270 mm - rotation: 0.33 sec - 120 kv, 300 mas/rotation - heart rate: 64-89 bpm courtesy: University Hospital of Munich Grosshadern, Munich 12/9/2008 Page 52 Dual Source CT: Results VII - dual source CT: fast visualization of the complete human anatomy in only 42 s with 0.33 mm isotropic resolution courtesy: University Hospital of Munich Grosshadern, Munich - spatial resolution: 0.33 mm - 42 s for 1889 mm - rotation: 0.5 sec - 120 kv, 120 mas/rotation - 1889 mm scan range Seite 26
27 12/9/2008 Page 53 Dual Source CT: Results VIII - dual source CT: excellent visualization of the complete peripheral artery tree showing an occlusion of the left iliac artery - spatial resolution: 0.33 mm - 31 s for 1389 mm - rotation: 0.5 sec - 120 kv, 200 mas/rotation - 1389 mm scan range courtesy: University Hospital of Munich Grosshadern, Munich 12/9/2008 Page 54 Dual Source CT: Results IX thanks to courtesy: University Hospital of Munich Grosshadern, Munich Seite 27
28 12/9/2008 Page 55 Micro CT Micro CT 12/9/2008 Page 56 Micro CT: Setup I X-ray tube rotating axis rotating object detector cone beam variable zooming - pre-clinical in vitro CT imaging - setup of a μ-ct scanner with fixed micro-focus X-ray tube and area detector while rotating object principle of μ-ct scanner X-ray tube rotating object detector photo of in vitro μ-ct scanner experimental setup (IMP Erlangen) source: Kalender. Computertomographie, Publicis MCD Verlag 2000 Seite 28
29 12/9/2008 Page 57 Micro CT: Resolution imaging of two tungsten wires with 10 µm thickness 3D imaging of bone biopsy osteporosis 3D imaging of a vessel stent for quality control source: Kalender. Computertomographie, Publicis MCD Verlag 2000 12/9/2008 Page 58 Micro CT: Setup II rotating gantry detector mouse couch - pre-clinical in vitro CT imaging - setup of a μ-ct scanner with rotating micro-focus X-ray tube and area detector while fixed object X-ray tube principle of μ-ct scanner rotating gantry detector mouse couch photo of in vitro μ-ct scanner (TomoScope 30s, VAMP GmbH, Erlangen) X-ray tube source: Kalender. Computertomographie, Publicis MCD Verlag 2000 Seite 29
30 12/9/2008 Page 59 Micro CT: Results I whole body scan with about 80 µm resolution source: Kalender. Computertomographie, Publicis MCD Verlag 2000 12/9/2008 Page 60 Comparison: CT and μ-ct in vitro μ-ct in vivo CT focus size x-ray tube power spatial resolution scan time detector field-of-view dose flat panel detector not relevant flat panel detector according to ALARA ALARA - principle = As Low As Reasonably Achievable source: Kalender. Computertomographie, Publicis MCD Verlag 2000 Seite 30
31 12/9/2008 Page 61 Micro CT: Results II Seite 31