Digital measurement and clinical significance of imaging parameters of occipital-C2 angle and posterior occipitocervical angle / 解剖学报

Objective To explore the differences and correlation of imaging parameters of occipital-C2 angle (OC2A) and posterior occipitocervical angle (POCA) between sex and age, so as to provide theoretical reference for fixing the position of head and neck in occipitocervical fusion. Methods The imaging data of 473 cases (339 males and 134 females) were collected and divided into 2 groups according to sex. Each group was subdivided into 6 groups according to age: ≤29 year-old, 30-39 year-old, 40-49 year-old, 50-59 year-old, 60-69 year-old and ≥70 year-old. OC2A and POCA were measured in Mimics software, and their differences with sex and age were statistically analyzed. Results There was no significant difference in OC2A and POCA between sexes (P0.05); There were significant differences in POCA between the male group of 30-39 year-old and ≤29 year-old (P<0.05), but between the group of 40-49 year-old and each group (P<0.05). In the female group, there was significant difference between the group of ≤29 year-old and all age groups (P<0.05), but there was no significant difference among the other groups (P<0.05). Pearson correlation analysis showed that there was a positive correlation between OC2A and POCA (r= 0.038, P<0.05), that is, there was no correlation between them. Conclusion There is no difference in OC2A and POCA values between sexes; there are differences in OC2A and POCA values in males among different age groups, suggesting that clinical attention should be paid to the age differences in males, while there is no difference in OC2A values in females, but POCA is different in different age groups. The changes of OC2A and POCA values in different age groups and sex provide a parameter basis for fixing the anatomical reduction angle of head and neck in occipitocervical fusion.

Reliability of 3D arterial spin labeling MR perfusion measurements: The effects of imaging parameters, scanner model, and field strength.

The aim of this study was to investigate the reliability of cerebral blood flow (CBF) measurements obtained by 3D pseudo-continuous arterial spin labeling (pCASL) imaging according to imaging parameters, scanner model, and field strength. We acquired 3D pCASL images in 12 healthy volunteers using four different scanners: two 3.0 T scanners and two 1.5 T scanners. Reliability was evaluated using intraclass correlation coefficient. Our results indicate that the influence of the post-labeling delay and scanner model on CBF measurements should be taken into consideration. If two scanners of the same model are used, scannerdependent differences may be small.

Does the aortic annulus undergo conformational change throughout the cardiac cycle? A systematic review.

Accurate annular sizing in transcatheter aortic valve implantation (TAVI) planning is essential. It is now widely recognized that the annulus is an oval structure in most patients, but it remains unclear if the annulus undergoes change in size and shape during the cardiac cycle that may impact prosthesis size selection. Our aim was to assess whether the aortic annulus undergoes dynamic conformational change during the cardiac cycle and to evaluate possible implications for prosthesis size selection. We performed a systematic search in PubMed and Embase databases and reviewed all available literature on aortic annulus measurements in at least two cardiac phases. Twenty-nine articles published from 2001 to 2014 were included. In total, 2021 subjects with and without aortic stenosis were evaluated with a mean age ranging from 11 ± 3.6 to 84.9 ± 7.2 years. Two- and three-dimensional echocardiography was performed in six studies each, magnetic resonance imaging was used in one and computed tomography in 17 studies. In general, the aortic annulus was more circular in systole and predominantly oval in diastole. Whereas the annular long-axis diameter showed insignificant change throughout the cycle, the short-axis diameter, area, and perimeter were significantly larger in systole compared with diastole. Hence, the aortic annulus does undergo dynamic changes during the cardiac cycle. In patients with large conformational changes, diastolic compared with systolic measurements can result in undersizing TAVI prostheses. Due to the complex annular anatomy and dynamic change, three-dimensional assessment in multiple phases has utmost importance in TAVI planning to improve prosthesis sizing.

High resolution CT of the lungs: Proper mA s settings for clinical use.

Fifty-five patients undergoing routine chest CT were examined with four additional high resolution computed tomography (HRCT) slices to determine the proper milliampere-second settings for clinical HRCT of the lungs. The following technical factors were used: 1-mm collimation, 2-s scan time, 120 kVp and different milliampere settings (160 mA, 100 mA, 60 mA, 30 mA). On 47 out of 54 patients all the four HRCT cuts were at exactly the same level. These images were independently reviewed and assessed by three radiologists. The body mass index was calculated in order to determine the effect of the size of the patient on the milliamperage setting needed. The standard deviation of CT values of 1 mm and 10 mm slice was measured in a Plexiglas phantom with different mA settings. The slice thickness was measured with thermoluminescence dosimeter. In the phantom study the change of milliamperage from 160 mA to 30 mA at 120 kVp and 2 s increased standard deviation in CT units from about 4.6 to 8.9 in 1 mm slice and from about 2.9 to 4.3 in 10 mm slice. The Computed Tomography Dose Index (CTDI) values of both 1 mm and 10 mm slices at 160 mA-30 mA were approximately from 9 to 2 cGy (rad). In the patient study 1 mm HRCT scans with 120 kVp/100 mA/2 s showed the same diagnostic information as 120 kVp/160 mA/2 s scans for all patients regardless of size. If only the normal weight patients are considered, all the details were also well seen with 120 kVp/60 mA/2 s settings. In our study contrary to earlier reports 30 mA/2s was inadequate for diagnosis. We conclude that at 120 kVp medium-dose settings 60-100 mA/2 s or 120-200 mA s are in clinical practice appropriate for HRCT studies of the lungs in most patients.