Axial scanning

Some discontinuities may be identified by a conventional two-dimensional ultrasonic technique, from which the well-known C-scan image is the most popular. The C-scan technique is relatively easy to implement and the results from several NDE studies have been very encouraging [1]. In the case of cylindrical specimens, a circular C-scan image is convenient to show discontinuity information. The circular C-scan image shows the peak amplitude of a back-scattered pulse received in the circular array. The axial scan direction is shown as a function of transducer position in the circular array. The circular C-scan image serves also as an initial step for choosing circular B-scan profiles. The latter provides a mapping between distance to the discontinuity and transducer position in the circular array. 

Hounsfield, G.N. Computerized transverse axial scanning (tomography). 1. Description of system. Br. J. Radiol. 46 1016-1022, 1973. 

To compare exposure between different CT protocols, one can use the absorbed dose, usually reported as the CT dose index (CTDI) in mGy. This concept was introduced by Jucius and Kambic to predict the multiple slice average dose at the center of a set of axial scans [35], The product of the CTDI j and the z-axis coverage for the particular scan then yields the dose-length product (DLP), where CTDI j is the average dose in the standard head CT dosimetry phantom [36, 37],... 

Fig. 1.62a,b. Acute appendicitis on color Doppler US. a B-mode US axial scan showing a two-ring-pattern appendicitis, b Color Doppler demonstrates hyperemia of the appendiceal wall manifested as an increased circumferential color flow, mostly in the submucosal layer... 

CAT Computed axial tomography Computer-aided tomography Computerized tomographic imaging Computerized tomography Computerized transverse axial scanning X-ray computed tomography... 

Fig. 14. Axial scan, CT. Narrowing of coronary sinus (arrow) ostium.

Fig. 15. Axial scan, maximum intensity projection. Anomalous course of great cardiac vein (arrow) with its opening into SVC.

Fig. 17. Accessory middle right pulmonary vein (arrow) seen at volumetric reconstruction and axial scan.

Recent literature (Lane et al. 2006) reports the opportunity, offered by multi-row CT scanners, to replace direct coronal scanning with reliable coronal reconstructions of image data from axial scanning. Reconstructions in any plane are thus possible... 

Our experience showed that using a 64 row multidetector CT and multiplanar projections improve the anatomic presentation of the bowel and produces fewer images that have orientations similar to those of conventional examinations. The axial images were always diagnostic, but MPR images were helpful for the observer s confidence and especially useful for demonstration of disease and changes who were not accustomed to axial scans. 

Fig. 17.4a,b. Axial scans thorough the transverse colon in the supine (a) and prone (b) positions with a lung window setting, a An 8 mm peduncolated polyp is visible on the anterior bowel wall (arrow) b in the prone position the polyp is covered by fluid. If only prone scans had been performed the polyp would not have been detected... 

Fig. 17.6a-c. Axial scan through the transverse colon in the supine position (a) and 3D endoscopic rendering mode (b,c). a Two identical filling defects on the anterior (arrow-object A) and posterior wall arrow point-object B). 3D images show that object A is a polyp (b, arrow) and that object B is a fold (c, arrows)... 

Fig. 5.2. Normal grey-scale ultrasound anatomy. Axial scan on the dorsal aspect of the penis showing the paired corpora cavernosa (CC), the corpus spongiosum (CS) and the penile septum (open arrows). The tunica albuginea (arrowheads) appears as a thin echogenic line surrounding the penile bodies. The Buck s fascia is visualized near the corpus spongiosum (curved arrows) while in the remaining portions is stuck on the tunica albuginea. The penile septum appears as an echogenic structure with back attenuation...

Fig. 5.7. Color Doppler ultrasound appearance of urethral arteries. Axial scan on the ventral aspect of the penis showing the paired urethral arteries (arrowheads) running within the corpus spongiosum...

Fig. 5.8a,b. Color Doppler ultrasound anatomy. Arrangement of the distal portion of the dorsal arteries, a Axial scan showing communication of the dorsal arteries behind the glans through a transverse anastomosis (open arrow), b Longitudinal scan showing a small dorsal collateral (arrowhead) feeding the corpus cavernosum... 

Fig. 5.9a,b. Color Doppler appearance of arterial communications (arrowheads) among the penile arteries. Axial scans on the ventral aspect of the penis, a Communication between the right cavernosal and urethral artery, b Communication between the right dorsal and cavernosal artery... 

Fig.5.11a-c. Depiction of penile veins (arrowheads) at color Doppler ultrasound, a Longitudinal scan showing deep dorsal vein. b,c Axial scans showing a large vein b in the ventral aspect of the penis between the corpora cavernosa and c portions of the emissary and circumflex veins... 

Fig. 8.7a-c. Unusual location of Peyronie s plaques (arrowheads). a Axial scan on the ventral aspect of the penis showing a partially calcified ventral plaque, b Axial scan on the right lateral aspect of the penis showing a partially calcified right-lateral plaque, c Longitudinal scan on the distal portion of the penis showing a dorsal plaque on the tip of a corpus cavernosum... 

Fig. 8.8a-c. Peyronie s plaques ( ) involving the adjacent structures, a Axial scan showing involvement of the penile septum, b Longitudinal scan showing encasement of the cavernosal artery (arrowheads), c Color Doppler longitudinal scan showing encasement of the dorsal artery (arrowheads)... 

Fig. 8.10a,b. Color Doppler ultrasound scans. Calcified dorsal plaques ( ). Normal penile vessels simulating plaque vascularization. a Axial scan showing left dorsal artery (open arrow) and an emissary vein passing through the plaque (arrowhead). b Communication between the cavernosal and the dorsal artery (arrowhead) passing though the plaque... 

Fig. 10.3a,b. Grey-scale appearance of the penile shaft after successful angiographic embolization of a right cavernosal artery tear, a Axial scan obtained 1 h after embolization shows a cavernous hematoma ( ) in the site of the embolized fistula within the right corpus cavernosum. A smaller hematoma (open arrow) not associated to cavernosal artery injury is recognized within the left corpus cavernosum as well, b Axial scan obtained 6 months later shows that the echotexture of the corpora cavernosa in the site of the previously embolized fistula is inhomogeneous due to fibrous changes. The patient, however, reported normal erections... 

Fig. 12.3a-c. Axial scans. Relationship between penile hematomas ( ) and the intact tunica albuginea, a Hematoma spreading outside the Buck s fascia (arrowheads), b Hematoma between the tunica albuginea (open arrow) and the Buck s fascia (arrowhead), c Hematoma within the left corpus cavernosum... 

Fig. 12.6. Penile fracture. Axial scan showing a large albu-gineal tear (open arrows) as interruption of the thin echo-genic line of the tunica albuginea (arrowheads) of the right corpus cavernosum. Associated extraalbugineal hematoma ( ) is also recognized...

Fig. 12.10. Isolated septal hematoma. Patient presenting with a lump in the mid shaft 1 month after severe bending of the erect penis during intercourse associated with pain and a snapping sensation. Axial scan showing a well-defined cys-tic-like area in the septal region ( ) consistent with postraumatic hematoma...

Fig. 14.1. An 84-year-old diabetic patient with penile cancer and inflammation. Axial scan showing a large tumor (arrowheads) involving the entire glans. A fluid collection is appreciable within the lesion ( ) with thickened echogenic wall and internal debris consistent with abscess formation...

Fig. 14.4a,b. Giant hemangioma of the penis, a Axial scan of the glans showing inhomogeneous echotexture by presence of multiple hypoechoic lacunae, b Axial scan on the tip of the corpora cavernosa showing a coarse echotexture of the sinusoidal spaces consistent with extension of the lesion into the corpora... 

Fig. 14.6a-c. Penile metastases. a Advanced bladder cancer. Axial scan of the penile shaft demonstrates diffuse ( ) and nodular (N) metastatic involvement of the corpora cavernosa. b Advanced prostate cancer showing isoechoic, barely visible metastatic nodules ( ). The tunica albuginea is thickened and hypoechoic, in particular, on the right dorsal aspect (arrowheads), and boundaries with the right cavernosal body are ill defined, consistent with tumor infiltration, c Biopsy proved diffuse infiltration of the shaft from recurrent bladder cancer. No distinct nodules are appreciable. The tunica albuginea is thickened, but no interruption is visible... 

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