Clinical Utility of Three-dimensional US1
Dónal B. Downey, MB, BCh, MSc ,
Aaron Fenster, PhD and
Jacqueline C. Williams, MA
1 From the Department of Diagnostic Radiology and Nuclear Medicine, London Health Sciences Centre, 339 Windermere Rd, London, Ontario, Canada N6A 5A5 (D.B.D., A.F., J.C.W.), and the John P. Robarts Research Institute, London, Ontario, Canada (D.B.D., A.F.). Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received April 13, 1999; revision requested May 17 and final revision received November 3; accepted November 3. Supported in part by grants from the Medical Research Council of Canada and the University Hospital (London) Research Foundation. Address reprint requests to D.B.D. (e-mail: ddowney@irus.rri.on.ca).
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Figure 1a. Tracked freehand 3D scanning. (a) Acoustically tracked 3D scanning. Diagram shows a triangular device consisting of three sound emitters mounted on a US transducer. As the operator moves the transducer, the sound-emitting devices are activated and begin to emit pulses that are detected by three microphones positioned in different locations above the patient. By measuring the time delay between sound emission and detection, the position and angulation of the transducer are continuously monitored. (b) Articulated-arm-tracked 3D scanning. Diagram shows a transducer mounted on a mechanical arm with multiple movable joints. Potentiometers at the joints are used to measure their rotation, allowing continuous monitoring of the position and angulation of the transducer. (c, d) Magnetic field-tracked 3D scanning. (c) Diagram shows a small electromagnetic device attached to a transducer. The adjacent box detector registers nearby changes in the electromagnetic field. The exact position of the transducer is computed based on the changes in electromagnetic signal detected by the box detector. (d) Photograph shows an abdominal scan being performed with a magnetic tracking device, which is attached to the transducer (T) with a black plastic cover (arrow). The box detector (D) is attached to the scanning table.
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Figure 1b. Tracked freehand 3D scanning. (a) Acoustically tracked 3D scanning. Diagram shows a triangular device consisting of three sound emitters mounted on a US transducer. As the operator moves the transducer, the sound-emitting devices are activated and begin to emit pulses that are detected by three microphones positioned in different locations above the patient. By measuring the time delay between sound emission and detection, the position and angulation of the transducer are continuously monitored. (b) Articulated-arm-tracked 3D scanning. Diagram shows a transducer mounted on a mechanical arm with multiple movable joints. Potentiometers at the joints are used to measure their rotation, allowing continuous monitoring of the position and angulation of the transducer. (c, d) Magnetic field-tracked 3D scanning. (c) Diagram shows a small electromagnetic device attached to a transducer. The adjacent box detector registers nearby changes in the electromagnetic field. The exact position of the transducer is computed based on the changes in electromagnetic signal detected by the box detector. (d) Photograph shows an abdominal scan being performed with a magnetic tracking device, which is attached to the transducer (T) with a black plastic cover (arrow). The box detector (D) is attached to the scanning table.
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Figure 1c. Tracked freehand 3D scanning. (a) Acoustically tracked 3D scanning. Diagram shows a triangular device consisting of three sound emitters mounted on a US transducer. As the operator moves the transducer, the sound-emitting devices are activated and begin to emit pulses that are detected by three microphones positioned in different locations above the patient. By measuring the time delay between sound emission and detection, the position and angulation of the transducer are continuously monitored. (b) Articulated-arm-tracked 3D scanning. Diagram shows a transducer mounted on a mechanical arm with multiple movable joints. Potentiometers at the joints are used to measure their rotation, allowing continuous monitoring of the position and angulation of the transducer. (c, d) Magnetic field-tracked 3D scanning. (c) Diagram shows a small electromagnetic device attached to a transducer. The adjacent box detector registers nearby changes in the electromagnetic field. The exact position of the transducer is computed based on the changes in electromagnetic signal detected by the box detector. (d) Photograph shows an abdominal scan being performed with a magnetic tracking device, which is attached to the transducer (T) with a black plastic cover (arrow). The box detector (D) is attached to the scanning table.
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Figure 1d. Tracked freehand 3D scanning. (a) Acoustically tracked 3D scanning. Diagram shows a triangular device consisting of three sound emitters mounted on a US transducer. As the operator moves the transducer, the sound-emitting devices are activated and begin to emit pulses that are detected by three microphones positioned in different locations above the patient. By measuring the time delay between sound emission and detection, the position and angulation of the transducer are continuously monitored. (b) Articulated-arm-tracked 3D scanning. Diagram shows a transducer mounted on a mechanical arm with multiple movable joints. Potentiometers at the joints are used to measure their rotation, allowing continuous monitoring of the position and angulation of the transducer. (c, d) Magnetic field-tracked 3D scanning. (c) Diagram shows a small electromagnetic device attached to a transducer. The adjacent box detector registers nearby changes in the electromagnetic field. The exact position of the transducer is computed based on the changes in electromagnetic signal detected by the box detector. (d) Photograph shows an abdominal scan being performed with a magnetic tracking device, which is attached to the transducer (T) with a black plastic cover (arrow). The box detector (D) is attached to the scanning table.
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Figure 2a. Untracked freehand 3D scanning. (a) Diagram illustrates the mechanical movement of the transducer across the skin. (b) Diagram shows how the transducer can be tilted about a fixed point on the skin surface. (c) Diagram shows how the transducer can be rotated about its own axis.
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Figure 2b. Untracked freehand 3D scanning. (a) Diagram illustrates the mechanical movement of the transducer across the skin. (b) Diagram shows how the transducer can be tilted about a fixed point on the skin surface. (c) Diagram shows how the transducer can be rotated about its own axis.
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Figure 2c. Untracked freehand 3D scanning. (a) Diagram illustrates the mechanical movement of the transducer across the skin. (b) Diagram shows how the transducer can be tilted about a fixed point on the skin surface. (c) Diagram shows how the transducer can be rotated about its own axis.
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Figure 3a. Mechanical 3D scanning. Photographs show a US transducer mounted in a plastic cradle (C) that is attached to a motorized device (M). The assembly is held completely still during acquisition. (a) Linear scanning. On activation, the motor moves the cradle and transducer down the tracks at a constant rate in a smooth, consistent manner (arrow). (b) Tilting scanning. On activation, the motor tilts the cradle and transducer at a constant rate in a smooth, consistent manner (arrow). (c) Rotational scanning. On activation, the motor rotates the cradle and transducer at a constant rate in a smooth, consistent manner (arrow).
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Figure 3b. Mechanical 3D scanning. Photographs show a US transducer mounted in a plastic cradle (C) that is attached to a motorized device (M). The assembly is held completely still during acquisition. (a) Linear scanning. On activation, the motor moves the cradle and transducer down the tracks at a constant rate in a smooth, consistent manner (arrow). (b) Tilting scanning. On activation, the motor tilts the cradle and transducer at a constant rate in a smooth, consistent manner (arrow). (c) Rotational scanning. On activation, the motor rotates the cradle and transducer at a constant rate in a smooth, consistent manner (arrow).
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Figure 3c. Mechanical 3D scanning. Photographs show a US transducer mounted in a plastic cradle (C) that is attached to a motorized device (M). The assembly is held completely still during acquisition. (a) Linear scanning. On activation, the motor moves the cradle and transducer down the tracks at a constant rate in a smooth, consistent manner (arrow). (b) Tilting scanning. On activation, the motor tilts the cradle and transducer at a constant rate in a smooth, consistent manner (arrow). (c) Rotational scanning. On activation, the motor rotates the cradle and transducer at a constant rate in a smooth, consistent manner (arrow).
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Figure 4a. Two-dimensional array scanning. With this acquisition method, the transducer obtains true 3D data from an array of detectors. (a) Diagram illustrates a pyramid-shaped pulse originating from a square-faced transducer. (b) Diagram illustrates a cylindric pulse originating from a circular-faced transducer.
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Figure 4b. Two-dimensional array scanning. With this acquisition method, the transducer obtains true 3D data from an array of detectors. (a) Diagram illustrates a pyramid-shaped pulse originating from a square-faced transducer. (b) Diagram illustrates a cylindric pulse originating from a circular-faced transducer.
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Figure 5. Multiplanar reformatting with texture mapping. Three-dimensional color Doppler US image of the carotid artery shows the sharply jagged irregularity of the vessel wall and the color pattern caused by slight variations in the beat-to-beat movement of the artery. The image was acquired with cardiac gating, which improves the quality of the 3D image but increases total imaging time.
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Figure 6. Volume rendering. Diagram shows how a ray interacts with a 3D volume image. The voxel values along each ray can be multiplied by selected factors and summed to produce different effects.
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Figure 7. Respiratory motion artifact. Three-dimensional B-mode US image of the breast shows a cluster of small cysts (green arrow) but is severely degraded by undulations (yellow arrows) caused by the patient's rapid breathing pattern. This involuntary motion also caused smearing of the underlying image in a reconstructed plane (blue arrows). Details of the cluster of cysts are completely obscured, and the data had to be reacquired. A = acquired plane; B, C = reconstructed planes.
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Figure 8. Artifact caused by incorrect calibration. Three-dimensional US image of the prostate gland acquired with rotational scanning with an end-fire transrectal US transducer shows a linear artifact in the middle of the gland (arrow). The artifact was caused by incorrect calibration of the scanning assembly. Note that no such artifact is seen in the near field. This artifact can be avoided by keeping the scanning assembly properly calibrated at all times.
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Figure 9. Fetal imaging. Volume-rendered 3D US image clearly depicts the fingers of a fetus.
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Figure 10. Fetal imaging. Multiplanar reformatted 3D US image shows the umbilical vein, an umbilical artery, the inferior vena cava (IVC), and the fetal heart. These complex data can be displayed on a single image. Data acquisition time for this scan was less than 20 seconds.
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Figure 11. Gynecologic imaging. Oblique-coronal endovaginal 3D US image demonstrates the uterine cornua (arrows) from a novel perspective. Endovaginal 3D US can be performed in less than 10 seconds, making it convenient for both patient and physician. Several authors have reported this modality to be useful in depicting a variety of clinical diseases, particularly congenital malformations of the uterus.
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Figure 12. Gynecologic imaging. Multiplanar reformatted 3D US image shows first-trimester twins with areas of implantation bleeding (arrows) adjacent to the gestational sacs (s1, s2). Three-dimensional US allowed accurate measurement of the areas of bleeding as well as long-term follow-up.
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Figure 13a. Gynecologic imaging. (a) Three-dimensional US image demonstrates enlarged ovarian follicles, whose sharp boundaries make volume measurement relatively easy. (b) On a 3D US image, one follicle has been delineated in green with the computer. Many assisted reproductive techniques cause ovarian hyperstimulation with resulting enlargement of the ovarian follicle. It is important to monitor follicular volume during a menstrual cycle to time fertilization accurately, but such monitoring is tedious with 2D US.
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Figure 13b. Gynecologic imaging. (a) Three-dimensional US image demonstrates enlarged ovarian follicles, whose sharp boundaries make volume measurement relatively easy. (b) On a 3D US image, one follicle has been delineated in green with the computer. Many assisted reproductive techniques cause ovarian hyperstimulation with resulting enlargement of the ovarian follicle. It is important to monitor follicular volume during a menstrual cycle to time fertilization accurately, but such monitoring is tedious with 2D US.
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Figure 14. Power Doppler imaging. Multiple volume-rendered images (A-D) from a power Doppler US angiography study demonstrate the normal spleen. Each image represents a frame from a cine loop.
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Figure 15a. Prostate imaging. (a) Ejaculatory duct cyst. Coronal 3D US image of the prostate gland shows a midline ejaculatory duct cyst with a classic "teardrop" shape (arrowheads). The relationship of the cyst, the seminal vesicles (sv), and the verumontanum (yellow arrow) is clearly depicted. White arrow indicates pubic symphysis. (b, c) Right-sided base tumor with tumoral invasion. (b) Three-dimensional US image shows a hypoechoic tumor (arrows) invading the seminal vesicles (sv), a finding that indicates that the patient probably should not undergo surgery. rw = rectal wall. (c) Three-dimensional US image again shows the hypoechoic tumor (arrows) invading the seminal vesicle (sv). A large defect caused by transurethral resection of the prostate gland is also seen (arrowhead).
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Figure 15b. Prostate imaging. (a) Ejaculatory duct cyst. Coronal 3D US image of the prostate gland shows a midline ejaculatory duct cyst with a classic "teardrop" shape (arrowheads). The relationship of the cyst, the seminal vesicles (sv), and the verumontanum (yellow arrow) is clearly depicted. White arrow indicates pubic symphysis. (b, c) Right-sided base tumor with tumoral invasion. (b) Three-dimensional US image shows a hypoechoic tumor (arrows) invading the seminal vesicles (sv), a finding that indicates that the patient probably should not undergo surgery. rw = rectal wall. (c) Three-dimensional US image again shows the hypoechoic tumor (arrows) invading the seminal vesicle (sv). A large defect caused by transurethral resection of the prostate gland is also seen (arrowhead).
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Figure 15c. Prostate imaging. (a) Ejaculatory duct cyst. Coronal 3D US image of the prostate gland shows a midline ejaculatory duct cyst with a classic "teardrop" shape (arrowheads). The relationship of the cyst, the seminal vesicles (sv), and the verumontanum (yellow arrow) is clearly depicted. White arrow indicates pubic symphysis. (b, c) Right-sided base tumor with tumoral invasion. (b) Three-dimensional US image shows a hypoechoic tumor (arrows) invading the seminal vesicles (sv), a finding that indicates that the patient probably should not undergo surgery. rw = rectal wall. (c) Three-dimensional US image again shows the hypoechoic tumor (arrows) invading the seminal vesicle (sv). A large defect caused by transurethral resection of the prostate gland is also seen (arrowhead).
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Figure 16a. Breast imaging. Multiplanar reformatted 3D US images of a portion of the nipple-areolar complex ) (a) and the nipple in profile (b) demonstrate duct ectasia and multiple simple cysts (green arrows). The oblique plane allows visualization of the serpiginous ducts (yellow arrow) from the cysts to the nipple (blue arrows) and facilitates understanding of the 3D imaging pattern of the disease.
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Figure 16b. Breast imaging. Multiplanar reformatted 3D US images of a portion of the nipple-areolar complex ) (a) and the nipple in profile (b) demonstrate duct ectasia and multiple simple cysts (green arrows). The oblique plane allows visualization of the serpiginous ducts (yellow arrow) from the cysts to the nipple (blue arrows) and facilitates understanding of the 3D imaging pattern of the disease.
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Figure 17a. Three-dimensional US-guided breast biopsy. A needle was advanced to the edge of the breast lesion, and 3D US was performed. (a) Three-dimensional US image obtained in the longitudinal (A) and transaxial (B) planes demonstrates the path of the needle. In the longitudinal plane, the needle (arrow) appears to reach the lesion (arrowheads), but the transaxial plane indicates that the needle is to the right of center. C = coronal plane. (b) On a 3D US image obtained in the transaxial (B) and coronal (C) planes, the needle (arrow) is high relative to the lesion (arrowheads). A = longitudinal plane. (c) Three-dimensional US image obtained in the longitudinal (A) and coronal (C) planes helps confirm that the needle (arrow) will miss the lesion (arrowheads). The needle was readjusted, and a satisfactory biopsy specimen was obtained.
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Figure 17b. Three-dimensional US-guided breast biopsy. A needle was advanced to the edge of the breast lesion, and 3D US was performed. (a) Three-dimensional US image obtained in the longitudinal (A) and transaxial (B) planes demonstrates the path of the needle. In the longitudinal plane, the needle (arrow) appears to reach the lesion (arrowheads), but the transaxial plane indicates that the needle is to the right of center. C = coronal plane. (b) On a 3D US image obtained in the transaxial (B) and coronal (C) planes, the needle (arrow) is high relative to the lesion (arrowheads). A = longitudinal plane. (c) Three-dimensional US image obtained in the longitudinal (A) and coronal (C) planes helps confirm that the needle (arrow) will miss the lesion (arrowheads). The needle was readjusted, and a satisfactory biopsy specimen was obtained.
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Figure 17c. Three-dimensional US-guided breast biopsy. A needle was advanced to the edge of the breast lesion, and 3D US was performed. (a) Three-dimensional US image obtained in the longitudinal (A) and transaxial (B) planes demonstrates the path of the needle. In the longitudinal plane, the needle (arrow) appears to reach the lesion (arrowheads), but the transaxial plane indicates that the needle is to the right of center. C = coronal plane. (b) On a 3D US image obtained in the transaxial (B) and coronal (C) planes, the needle (arrow) is high relative to the lesion (arrowheads). A = longitudinal plane. (c) Three-dimensional US image obtained in the longitudinal (A) and coronal (C) planes helps confirm that the needle (arrow) will miss the lesion (arrowheads). The needle was readjusted, and a satisfactory biopsy specimen was obtained.
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Copyright © 2000 by the Radiological Society of North America.
