Chapter8 - Course: BIM 241, University of California Davis,...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 LESION DETECTABILITY Contrast/Noise Spatial Resolution Volume Imaged (slices x area/slice x slice thickness) area/slice slice thickness) Presence of Artifacts Scan Parameters FUNDAMENTAL IMAGING OBJECTIVES Maximize Lesion Detectability Minimize Scan Time Tissue Parameters System Specifications Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 1 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 FUNDAMENTAL PARAMETERS SCAN PARAMETERS: Body, Head, Surface Coil Single slice, Multislice, or Volume Slice Orientation,Thickness, Spacing, Start/End Location Pulse Sequence (MEMP, IR, VEMP, Fast Scan) Sequence (MEMP IR VEMP Fast Scan) NEX # views TR TE FOV Frequency Direction Receiver Attenuation Transmitter Attenuation Center Frequency Options: Respiratory Compensation, Cardiac Gating, Flow Compensation, Classic Gradient Waveforms Database Options: Presaturation, Zoom, No Phase Wrap FUNDAMENTAL PARAMETERS (cont.) (cont.) TISSUE PARAMETERS: T1 T2, T2* Proton Density Motion SYSTEM SPECIFICATION PARAMETERS: Signal to Noise T1:T2 Contrast Contrast Spatial Resolution Image Uniformity Slice Thickness and Profile Geometric Distortion Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 2 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Spin echo image weighting Weighting Proton density T1T1-weighting T2T2-weighting Pulse sequence Pulse sequence parameters parameters long TR, short TE short TR, short TE Long TR, long TE Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 3 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 PARAMETER: TR: Increase ADVANTAGES: a. Increased signal intensity, all tissues (unequally, primarily dependent upon tissue T1) b. Increase number of slices available/series DISADVANTAGES: a. Increased examination time b. Generally decreased T1-based contrast T1(if TR > approx. 1000 msec.) a. Decreased signal intensity, all tissues ti (unequally, primarily dependent upon T1) b. Decreased number of slices available/series Decrease a. Decreased examination ti time b. Generally increased T1T1-based contrast (if TR < approx. 1000 msec.) Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 4 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 5 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 6 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 7 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 8 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 9 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 10 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 PARAMETER: TE: Increase ADVANTAGES: DISADVANTAGES: a. Potentially increased T2T2-based contrast a. Decreased signal intensity, all tissues (unequally, dependent primarily upon tissue T2) a. Potentially decreased T2-based contrast T2- Decrease a. Increased signal intensity, all tissues (unequally, dependent primarily primarily upon T2) Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 11 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 12 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 13 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 14 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 PARAMETER: Slice Thickness: Increase ADVANTAGES: a. Increased signal from all tissues from all tissues b. Increased area b. traversed by one series of images DISADVANTAGES: a. Decreased resolution b. Increased partialpartialvolume artifacts especially at narrow interfaces a. Decrease signal, all ti tissues b. Decreased anatomic area traversed by a series of images Decrease a. Increased resolution b. Decreased partial volume artifacts Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 15 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 16 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 17 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Number of Slices number of slices = TR TR TE + option delays + overhead e.g., TR 600 TR = 600 ms, TE = 15 ms, one SAT = 5ms TE 15 SAT overhead = 10 ms number of slices = 20 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 18 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 19 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 20 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Volume Imaged Coronal Coronal and sagittal image planes allow larger volumes of tissue to be examined Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 21 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Volume Imaged Head: R/O seizure, T2W axial TR = 2400, TE2 = 90, # of slices = 23 slice thickness = 5.0 mm, slice gap = 1.0 mm FOV = 20 cm, volume covered = 13.7 cm FOV Head: R/O seizure, T2W coronal TR = 2500, TE2 = 90, # of slices = 24 slice thickness = 3.0 mm, slice gap = 0.6 mm FOV = 20 cm, volume covered = 8.6 cm FOV Volume Imaged C-spine: R/O spinal stenosis, T1W sagittal TR = 450, TE = 20, # of slices = 18 slice thickness = 3 mm, slice gap = 0.5 mm FOV = 22 cm, volume covered = 6.6 cm FOV C-spine: R/O spinal stenosis, T2*W volume TR = 20, TE = 7, # of slices = 60 (axial) slice thickness = 1.5 mm, slice gap = 0.0 mm FOV = 16 cm, volume covered = 9.0 cm FOV Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 22 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Volume Imaged Abdomen: R/O mass, T1W coronal, localizer TR = 400, TE = 20, # of slices = 16 slice thickness = 10.0 mm, slice gap = 2.0 mm FOV = 32-40 cm, volume covered = 17.2 cm FOV 32Abdomen: R/O mass, T2W axial TR = 2000, TE2 = 90, # of slices = 20 slice thickness = 6.0 mm, slice gap = 1.2 mm FOV = 28-32 cm, volume covered = 13.2 cm FOV 28- Matrix Size worse S/N more scan time better resolution better S/N less scan time less resolution Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 23 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 SPATIAL RESOLUTION represents 128x256 image matrix represents 256x256 image matrix Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 24 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 25 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 26 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 FIELD OF VIEW (FOV) FOV may be decreased to reduce pixel size # views = 128 # views = 128 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 27 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Field Of View (FOV) better S/N less resolution worse S/N more resolution Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 28 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 29 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Special coils with small FOV (Surface coils) Improve Improve spatial resolution Preserve Preserve or improve S/N Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 30 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 31 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 32 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 33 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 34 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 35 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 36 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 37 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 38 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Slight 1 cm peak to peak 3 cm/sec peak velocity 20% activity Moderate 1 cm peak to peak 3 cm/sec peak velocity 50% activity Severe 1 cm peak to peak 4 cm/sec peak velocity 90% activity Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 39 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 40 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 41 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 42 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 43 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 44 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 45 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 VARIABLE BANDWIDTH (VB) FEATURE: For For Long TE’s Narrow Narrow Bandwidth/Increase Readout Time 16 KHz → 4 KHz 16 BENEFIT: Increase Increase S/N TRADEOFFS: Increase Chemical Shift Increase Chemical Shift Late Echo Late Chemical Chemical Sat Increase Increase Flow Artifacts Flow Flow Comp Sat Sat Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 46 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 47 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 48 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 49 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 CHEMICAL Scan Time = NEX * #views * TR NEX = Number of Excitations per data point (data averages) #views = Number of Views TR = Repetition Time Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 50 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Scan Time = (NEX) (#views) (TR) (NEX) (2) (192) (2.0) = 768 seconds = 12.8 minutes MR EXAM TIME TR 0.25 0.5 1.0 1.5 2 .0 1 NEX 32 sec 1min 4sec 2min 8sec 3min 12sec 4min 16sec 16sec 2 NEX 1min 4sec 2min 8sec 4min 16sec 6min 24sec 8min 32sec 32sec 4 NEX 2min 8sec 4min 16sec 8min 32sec 12min 48sec 17min 4sec 4sec 6 NEX 3min 12sec 6min 24sec 12min 48sec 19min 12sec 25min 36sec 36sec Resolution – 256x128, no pulses for equilibrium Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 51 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 Imaging Trade-Offs TradeScan Time Time Signal/Noise Spatial Resolution #view NEX TR ½ #views ½ NEX ½ TR Tissue contrast Edge sharpness Granularity Fine structure detection sensitivity NC NC NC ± NC Signal difference Pixel size Noise-to-signal level Noise-toSignal difference & pixel size & noise level Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. fine structure detection sensitivity IMAGE APPEARANCE edge sharpness tissue contrast granularity * * * 52 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 SCAN TIME REDUCTION TECHNIQUES DO Compromise Imaging Objectives ↓ NEX ↓ TR ↓ #views → → ↓ C/N ↓ Spatial Resolution Resolution ↓ Number of Slices, ↓ C/N ↓ #views → ↓ #views ↓ FOV, → ↓ C/N ↓ FOV, ↓ bandwidth → ↑ chemical shift artifact, ↓ number of Slices DO NOT Compromise Imaging Objectives ↓ TR, ↑ NEX, optimize flip angle, 3D acquisition ↓ NEX, ↓ #views or ↓ TR consistent with limits imposed by patient motion Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 53 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 SNR ANALYSIS NEX required in GRE scan to match SNR of standard P.D. and T2 Weighted Spin Echo Scan Proton Density MPGR: MPGR T2 Weighted MPGR: Proton Density Volume GRE: Density Volume GRE: T2 Weighted Volume GRE: 8 NEX NEX 4 NEX 64 NEX NEX 32 NEX T2 WEIGHTED ACQUISITION Time padding per slice: 15 ms PARAMETERS SPIN ECHO SCAN GRADIENT RECALLED ECHO SCAN T1 900 ms T2 90 ms TR TE # slices possible FLIP ANGLE SIGNAL LEVEL #ACQS TO MATCH # OF SLICE 2700 80 28 90 0.93 1 1 35 25 32 10 0.1 .88 0.330267478 TIME TO ACQ. SAME # OF SLICES AT EQUAL SNR 28 Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 54 Course: BIM 241, University of California Davis, Instructor: Michael H. Buonocore 11/2/2008 END Do not distribute this document. Use of this document is restricted to persons enrolled in the BIM 241 course, UC Davis. 55 ...
View Full Document

This note was uploaded on 10/15/2010 for the course BIM BIM251 taught by Professor Buonocore during the Spring '09 term at UC Davis.

Ask a homework question - tutors are online