(1) Phantom calibrations:
(i) Penumbra-Spread = 2.4 pixels (1.30mm) using a 1.2mm X-ray tube focal-spot.
(ii) Measurements: Distance & area/volume - At 1% low-contrast,
accurate to less than 1/10th of a pixel.
e.g.
Guide-wire thickness: (manufacturer's specification) = 0.89mm; measured by a software ruler = 0.91mm,
error = 2.25% (Figure 1).
(iii) High Contrast Resolution - Modulation Transfer Function (MTF) (measured by Judy Method (Ref.
2)) - Improved from 3.38 to 9.61 lp/cm at 50% normalized modulation after 7x magnification and enhancement.
(iv) Processing Time - 7x magnification & enhancement of Region of Interest (ROI) of size 107x107pixel2 took 1.17 seconds by a 2.4GHz-CPU.
(2) Field Examples:
(I) & (II) 70-year-old patient CTA images of an aneurysm of the anterior communication artery over two successive years (2008-2009) were analyzed.
30 successive slices of CT Angiogram of 0.5mm slice-thickness to cover the whole effect of an aneurysm of the anterior communicating artery were enhanced and measured to detect the changes in the Average Width (d = 2 x SQR(A/pi),
where A = area of the edge-contour of the effect) and the width in the Y-axis direction (or Y-Axis Width).
The analysis of one of the 30 slices,
e.g.
IMG00199 in 2008 was used to demonstrate the features of the CAD.
Figures 2,
3,
& 4 showed the original image with ROI placed on the aneurysm,
7xROI images of 'before' and 'after' enhancement placed side-by-side,
and 7xROI enhanced image with annotations for the measurements.
Sharp edge-profile after enhancement facilitated clearer diagnosis and accurate measurements.
Area,
A of edge-profile of IMG00199 via outlining = 59.33±1.28mm2,
Average Width,
d =8.69±.01mm,
and Y-Axis Width =7.58±.01mm.
The elongated pear shape as shown in Figures 2-4 was caused by the branching off of arteries in the X-Axis direction.
For this reason,
only Y-Axis Width is used for this studies,
but its effect should also be picked up by the overall Average Width,
d measurement,
which is listed out in the following Table.
Table 1 showed the measurements of both the Average Width,
d,
and the Y-Axis Width of the various scanned slice positions ranging from one end to the other end of the effect using the 2008 data.
Table 1
Slice Outlining Average, Y-Axis Width
Code A,
in mm2 d,
in mm. in mm.
IMG00180 20.41±.75mm2 5.10 mm 5.91±.01 mm
IMG00181 24.42±0.82 " 5.58 “ 5.97 “
IMG00182 29.22±0.90 6.10 6.17
IMG00183 36.66±1.00 6.83 6.53
IMG00184 44.94±1.11 7.56 7.13
IMG00185 50.47±1.18 8.02 7.51
IMG00186 56.49±1.25 8.48 7.69
IMG00187 61.10±1.30 8.82 7.91
IMG00188 64.77±1.34 9.08 8.09
IMG00189 67.61±1.36 9.28 8.11
IMG00190 69.42±1.38 9.40 8.20
IMG00191 70.85±1.40 9.50 8.25
IMG00192 70.40±1.38 9.47 8.01
IMG00193 70.80±1.40 9.49 8.06
IMG00194 70.93±1.40 9.50 7.94
IMG00195 69.07±1.38 9.38 7.81
IMG00196 66.14±1.35 9.18 7.72
IMG00197 62.83±1.32 8.94 7.62
IMG00198 67.72±1.31 9.29 7.91
IMG00199 59.33±1.28 8.69 7.58
IMG00200 53.74±1.22 8.27 7.40
IMG00201 50.33±1.18 8.01 7.06
IMG00202 43.41±1.09 7.43 6.73
IMG00203 36.31±1.00 6.80 6.38
IMG00204 29.17±0.90 6.09 5.82
IMG00205 24.76±0.83 5.61 5.64
IMG00206 21.47±0.77 5.23 5.26
IMG00207 18.56±0.71 4.86 5.00
IMG00208 14.79±0.64 4.34 4.72
IMG00209 11.49±0.57 3.82 4.06
Table 2 showed the similar measurements for the same aneurysm of the same patient using the 2009 data.
Table 2
Slice Outlining Average, Y-Axis Width
Code A,
in mm2 d,
in mm. in mm.
IMG00222 27.01±0.86mm25.86 mm 6.33±.01 mm
IMG00223 32.57±0.95 " 6.44 “ 6.74 “
IMG00224 43.59±1.10 7.45 7.11
IMG00225 49.79±1.17 7.96 7.52
IMG00226 57.25±1.26 8.54 7.73
IMG00227 60.65±1.29 8.79 8.05
IMG00228 65.60±1.34 9.14 8.27
IMG00229 68.46±1.37 9.33 8.60
IMG00230 71.85±1.41 9.56 8.81
IMG00231 73.85±1.43 9.70 8.81
IMG00232 76.25±1.45 9.85 8.78
IMG00233 77.42±1.46 9.92 8.78
IMG00234 77.27±1.46 9.92 8.38
IMG00235 76.85±1.45 9.89 8.43
IMG00236 75.79±1.44 9.82 8.11
IMG00237 73.55±1.42 9.68 8.21
IMG00238 70.33±1.39 9.46 8.07
IMG00239 66.36±1.35 9.19 7.85
IMG00240 62.41±1.31 8.91 7.71
IMG00241 58.80±1.27 8.65 7.71
IMG00242 55.76±1.24 8.43 7.62
IMG00243 49.80±1.17 7.96 7.31
IMG00244 44.20±1.10 7.50 7.11
IMG00245 38.40±1.02 6.99 6.71
IMG00246 31.46±0.93 6.33 6.35
IMG00247 26.22±0.85 5.78 5.86
IMG00248 22.93±0.79 5.40 5.64
IMG00249 18.89±0.72 4.90 5.10
IMG00250 14.76±0.64 4.34 4.75
IMG00251 11.05±0.55 3.75 4.13
Figure 5 showed the graph-plots of the various Average Width and the Y-Axis Width of 2008 and 2009 versus their respective Slice-Positions (slice-thickness=0.5mm).
With the exception of one point within the graph profile of the Average Width of the 2008 data,
the smoothness of the graph-plots in general did indicate the good accuracies in measurements.
Maximum Average Width and maximum Y-Axis Width had increased from 9.50±.01mm to 9.92±.01mm or 4.42% and from 8.25±.01mm to 8.81±0.01mm or 6.79% respectively over the two successive year period.
Possible applications – (a) Accurately measured results may be used for the prognosis study (Refs.
3-8) e.g.
size versus rupture rate (Ref.
8),
and,
(b) in 4D quantitative growth monitoring of the aneurysm and the treatment decision making.
(III) One slice of a MR breast tumor of a 62 year-old patient with Scan Sequence of MR: 3D T1 W Fat suppressed with Gadolinium enhancement (T1_3D_FS+GD).
Figures 6,
7,
& 8 showed the original image with ROI placed on the tumor,
7xROI images of 'before' and 'after' enhancement placed side-by-side,
and 7xROI enhanced image with annotations for the measurements.
Area and volume of the tumor were measured as follows:
(i) Area,
A =188.31±1.52mm2 (if fitted into a circle,
then the Average Width of the circle,
d = 2x SQR(A/pi) = 2x SQR(188.31/pi) =15.48±1.23mm);
and,
(ii) Volume,
V = Area x slice-thickness = 564.93±4.56mm3.
Possible applications - (a) Accurately measured result may be used for
the prognosis study (Ref.
9),
and,
(b) 4D field trial measurements &/or oncological treatment monitoring.
(IV) One slice of a MR breast tumor of a 49 year-old patient with Scan Sequence of MR: T2 W_FS SENSE.
Figures 9,
10,
& 11 showed the original image with ROI placed on the tumor,
7xROI images of 'before' and 'after' enhancement placed side-by-side,
and 7xROI enhanced image with annotations for the measurements.
Area and volume of the tumor were measured as follows:
(i) Area,
A = 464.73±2.54mm2 (if fitted into a circle,
then the Average Width of the circle,
d = 2x SQR(A/pi) =2x SQR(464.73/pi) = 24.33±1.59mm; and,
(ii) Volume,
V = Area x slice-thickness = 1394.20±7.62mm3.
Possible applications - (a) Accurately measured result may be used for the prognosis study (Ref.
9),
and,
(b) 4D field trial measurements &/or oncological treatment monitoring.