Teng-Fu Tsao

Correlation Study of the Strength of the Color Doppler Twinkling Artifact with the Roughness of the Reflecting Surface and the Doppler Angles

Background The color Doppler twinkling artifact is manifested as a rapidly changing mixture of red and blue colors behind a strongly reflecting structure. The effects of the roughness of the reflecting surface and the Doppler angle on the intensity of the twinkling artifact have never been quantitatively reported before. In this study, a simple in vitro system with reproducible results was established to observe the effects of these two factors on the strength of the twinkling artifact. Materials and Methods Six different grits of water sandpapers were simultaneously scanned in a water bath with a fixed probe. In part 1, the computer calculated the pixels of color Doppler twinkling artifact behind each water sandpaper. In part 2, the signals of twinkling artifacts with different sandpaper sizes and different Doppler angles were recorded and analyzed. Results In part 1, the twinkling artifact was identified persistently and more intensely behind water sandpapers that had greater surface roughness. In part 2, different Doppler angles revealed less obvious effects on the strength of the twinkling artifacts in a certain range of angles, but would drastically decrease the intensity in the steeper angles. Conclusions We have established a simple model system with water sandpapers for the evaluation of the twinkling artifact. Our data confirmed the assumption that the roughness of the reflecting surface is directly related to the strength of the twinkling artifact. In addition, the Doppler angle affects the intensity of the artifact, but only in the steeper angles.

Sonographic Diagnosis of a Subclinical Wandering Spleen Role of the Decubitus Position

A wandering spleen is a rare condition. It is usually diagnosed when abdominal pain develops secondary to splenic torsion. Although splenic hypermobility is the pathognomonic feature of a wandering spleen, it is rarely revealed by imaging in the subclinical stage. We report 3 patients with a subclinical wandering spleen who had incidental sonographic findings of splenomegaly. Gray scale and color Doppler sonography in the right decubitus position can easily show the migratory nature and perfusion status of a wandering spleen in real time.

The Performance of Noncontrast Magnetic Resonance Angiography in Detecting Renal Artery Stenosis as Compared With Contrast Enhanced Magnetic Resonance Angiography Using Conventional Angiography as a Reference.

Objective The aims of this study were to evaluate the performance of noncontrast magnetic resonance angiography (NC MRA) for detecting renal artery stenosis (RAS) as compared with contrast-enhanced magnetic resonance angiography (CE MRA) and to evaluate the clinical feasibility, technical success rate, and performance of NC MRA for detecting RAS as compared with CE MRA. Methods Thirty-six subjects who underwent NC MRA and/or CE MRA were enrolled. Feasibility, technical success rate, and image quality scores were compared. Diagnostic ability was calculated using conventional angiography as a reference. Results Noncontrast MRA had higher feasibility and technical success rates than CE MRA did (100% and 97.2% vs 83.3% and 90%, respectively). Noncontrast MRA yielded significantly better image quality in motion artifact (P = 0.016). The diagnostic ability for detecting RAS is without significant difference between NC MRA and CE MRA. Conclusion Although NC MRA and CE MRA demonstrated comparable ability in diagnosing RAS, NC MRA achieved better technical success rates, feasibility, and image quality in motion artifacts than CE MRA did.

Multiple symmetric lipomatosis in two chinese patients, one typical and one unusual.

Multiple symmetric lipomatosis (MSL; Madelung disease) is an uncommon disorder with diffuse multiple symmetrical unencapsulated accumulations of fat located in the neck and the upper trunk. MSL usually occurs in middle aged Caucasian men of Mediterranean ancestry with a history of alcoholism. In the past decade, an increasing number of cases in the Chinese population have been reported which appear to be limited to the head and neck regions. We describe two Chinese patients with MSL who have a history of alcoholism. The MR and CT findings disclosed that one patient had the typical accumulation of unencapsulated fat in the neck and upper back, while the other patient had more than the typical neck involvement and an unusual distribution of fat in the scrotum.

The Magnetic Resonance Diagnosis of a Rare Case of Herlyn-Werner-Wunderlich Syndrome in a Newborn

The clinical and magnetic resonance imaging (MRI) findings of a rare case of Herlyn-Werner-Wunderlich (HWW) syndrome in a female newborn are described. At delivery, a soft interlabial mass was present and MRI revealed congenital anomalies including uterus didelphys, obstructed right-sided hemivagina with prolapsed hydrocolpos, and ipsilateral renal agenesis. The infant underwent successful incision of the obstructing vaginal septum, recovered well after surgery, and was discharged two weeks later.

Improvement of the Image Quality of Black-blood Magnetic Resonance Imaging with the Subtraction Double Inversion Recovery Technique

Black-blood images acquired with the double inversion recovery (IR) sequence in cardiovascular magnetic resonance imaging are commonly applied to distinguish the vessel wall from the lumen to evaluate vascular pathology. However, inadequate suppression of blood signals may introduce artifacts and cause mistakes. The objective of the current study was to determine whether subtraction double IR black-blood imaging improved the image quality. 11 scans from four rabbits were scanned using the conventional and subtraction T1 weighted double IR imaging. The subtraction method involved two scans with a third IR sequence with a series of inversion time (TI) settings in one of them. Each black-blood image was qualitatively evaluated based on contrast-to-noise ratio (CNR), signal-tonoise ratio (SNR), and noises. Using the best TI setting (575 ms), subtraction black-blood imaging yielded significantly better black-blood effects with a 48.6% increase in mean CNR between the area of the left carotid artery and adjacent paravertebral muscles (PM) and a 30.7% increase in mean CNR between the area of the left jugular vein and adjacent PM compared with the conventional method (5.65 vs. 3.81 and 6.8 vs. 5.21, both p values ＜ 0.05). The subtraction black-blood imaging did not significantly deteriorate image quality regarding noises and mean SNRs in the area of PM. Subtraction double IR black-blood imaging is better than the conventional method in black-blood effects of blood signals.

Image quality improvement in three-dimensional time-of-flight magnetic resonance angiography using the subtraction method for brain and temporal bone diseases.

Background: Time‐of‐flight (TOF) magnetic resonance (MR) angiography is based on flow‐related enhancement using the T1‐weighted spoiled gradient echo, or the fast low‐angle shot gradient echo sequence. However, materials with short T1 relaxation times may show hyperintensity signals and contaminate the TOF images. The objective of our study was to determine whether subtraction three‐dimensional (3D) TOF MR angiography improves image quality in brain and temporal bone diseases with unwanted contaminations with short T1 relaxation times. Methods: During the 12‐month study period, patients who had masses with short T1 relaxation times noted on precontrast T1‐weighted brain MR images and 24 healthy volunteers were scanned using conventional and subtraction 3D TOF MR angiography. The qualitative evaluation of each MR angiogram was based on signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR) and scores in three categories, namely, (1) presence of misregistration artifacts, (2) ability to display arterial anatomy selectively (without contamination by materials with short T1 relaxation times), and (3) arterial flow‐related enhancement. Results: We included 12 patients with intracranial hematomas, brain tumors, or middle‐ear cholesterol granulomas. Subtraction 3D TOF MR angiography yielded higher CNRs between the area of the basilar artery (BA) and normal‐appearing parenchyma of the brain and lower SNRs in the area of the BA compared with the conventional technique (147.7 ± 77.6 vs. 130.6 ± 54.2, p < 0.003 and 162.5 ± 79.9 vs. 194.3 ± 62.3, p < 0.001, respectively) in all 36 cases. The 3D subtraction angiography did not deteriorate image quality with misregistration artifacts and showed a better selective display of arteries (p < 0.0001) and arterial flow‐related enhancement (p < 0.044) than the conventional method. Conclusion: Subtraction 3D TOF MR angiography is more appropriate than the conventional method in improving the image quality in brain and temporal bone diseases with unwanted contaminations with short T1 relaxation times.