Impact of inverse unequal height strut structure on the functional performance of an additively manufactured cardiovascular stent.

Recently, additive manufacturing (AM) has been investigated as an innovative method to manufacture stents due to its capability in producing complex and customized structures. In this paper, the cardiovascular stents of M-type and N-type with inverse unequal height strut structure and N-type with equal height strut structure were designed and manufactured by Selective Laser Melting (SLM). Following surface polishing, balloon expansion, plane compression and three-point bending experiments were carried out to evaluate the mechanical performance of the stent. The stents designed with inverse unequal height strut structure showed higher radial support performance and lower radial recoil when compared to the stents with uniform design. This study proved the feasibility of SLM in rapid manufacturing of cardiovascular stents that can be used for performance evaluation in design stage.

[Three-dimensional printed 316L stainless steel cardiovascular stent's electrolytic polishing and its mechanical properties].

The interventional therapy of vascular stent implantation is a popular treatment method for cardiovascular stenosis and blockage. However, traditional stent manufacturing methods such as laser cutting are complex and cannot easily manufacture complex structures such as bifurcated stents, while three-dimensional (3D) printing technology provides a new method for manufacturing stents with complex structure and personalized designs. In this paper, a cardiovascular stent was designed, and printed using selective laser melting technology and 316L stainless steel powder of 0-10 µm size. Electrolytic polishing was performed to improve the surface quality of the printed vascular stent, and the expansion behavior of the polished stent was assessed by balloon inflation. The results showed that the newly designed cardiovascular stent could be manufactured by 3D printing technology. Electrolytic polishing removed the attached powder and reduced the surface roughness Ra from 1.36 µm to 0.82 µm. The axial shortening rate of the polished bracket was 4.23% when the outside diameter was expanded from 2.42 mm to 3.63 mm under the pressure of the balloon, and the radial rebound rate was 2.48% after unloading. The radial force of polished stent was 8.32 N. The 3D printed vascular stent can remove the surface powder through electrolytic polishing to improve the surface quality, and show good dilatation performance and radial support performance, which provides a reference for the practical application of 3D printed vascular stent.

Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease: systematic review and meta-analysis.

OBJECTIVES: To determine the correlation between CT measurements of emphysema or peripheral airways and airflow obstruction in chronic obstructive pulmonary disease (COPD). METHODS: PubMed, Embase and Web of Knowledge were searched from 1976 to 2011. Two reviewers independently screened 1,763 citations to identify articles that correlated CT measurements to airflow obstruction parameters of the pulmonary function test in COPD patients, rated study quality and extracted information. Three CT measurements were accessed: lung attenuation area percentage < -950 Hounsfield units, mean lung density and airway wall area percentage. Two airflow obstruction parameters were accessed: forced expiratory volume in the first second as percentage from predicted (FEV(1) %pred) and FEV(1) divided by the forced volume vital capacity. RESULTS: Seventy-nine articles (9,559 participants) were included in the systematic review, demonstrating different methodologies, measurements and CT airflow obstruction correlations. There were 15 high-quality articles (2,095 participants) in the meta-analysis. The absolute pooled correlation coefficients ranged from 0.48 (95 % CI, 0.40 to 0.54) to 0.65 (0.58 to 0.71) for inspiratory CT and 0.64 (0.53 to 0.72) to 0.73 (0.63 to 0.80) for expiratory CT. CONCLUSIONS: CT measurements of emphysema or peripheral airways are significantly related to airflow obstruction in COPD patients. CT provides a morphological method to investigate airway obstruction in COPD. KEY POINTS: • Computed tomography is widely performed in patients with chronic obstructive pulmonary disease (COPD) • CT provides quantitative morphological methods to investigate airflow obstruction in COPD • CT measurements correlate significantly with the degree of airflow obstruction in COPD • Expiratory CT measurements correlate more strongly with airflow obstruction than inspiratory CT • Low-dose CT decreases the radiation dose for diagnosis and quantitative emphysema evaluation.

Preoperative subtyping of meningiomas by perfusion MR imaging.

INTRODUCTION: This paper aims to evaluate the value of perfusion magnetic resonance (MR) imaging in the preoperative subtyping of meningiomas by analyzing the relative cerebral blood volume (rCBV) of three benign subtypes and anaplastic meningiomas separately. MATERIALS AND METHODS: Thirty-seven meningiomas with peritumoral edema (15 meningothelial, ten fibrous, four angiomatous, and eight anaplastic) underwent perfusion MR imaging by using a gradient echo echo-planar sequence. The maximal rCBV (compared with contralateral normal white matter) in both tumoral parenchyma and peritumoral edema of each tumor was measured. The mean rCBVs of each two histological subtypes were compared using one-way analysis of variance and least significant difference tests. A p value less than 0.05 indicated a statistically significant difference. RESULTS: The mean rCBV of meningothelial, fibrous, angiomatous, and anaplastic meningiomas in tumoral parenchyma were 6.93 +/- 3.75, 5.61 +/- 4.03, 11.86 +/- 1.93, and 5.89 +/- 3.85, respectively, and in the peritumoral edema 0.87 +/- 0.62, 1.38 +/- 1.44, 0.87 +/- 0.30, and 3.28 +/- 1.39, respectively. The mean rCBV in tumoral parenchyma of angiomatous meningiomas and in the peritumoral edema of anaplastic meningiomas were statistically different (p < 0.05) from the other types of meningiomas. CONCLUSION: Perfusion MR imaging can provide useful functional information on meningiomas and help in the preoperative diagnosis of some subtypes of meningiomas.

Perfusion MR imaging for differentiation of benign and malignant meningiomas.

INTRODUCTION: Our purpose was to determine whether perfusion MR imaging can be used to differentiate benign and malignant meningiomas on the basis of the differences in perfusion of tumor parenchyma and/or peritumoral edema. METHODS: A total of 33 patients with preoperative meningiomas (25 benign and 8 malignant) underwent conventional and dynamic susceptibility contrast perfusion MR imaging. Maximal relative cerebral blood volume (rCBV) and the corresponding relative mean time to enhance (rMTE) (relative to the contralateral normal white matter) in both tumor parenchyma and peritumoral edema were measured. The independent samples t-test was used to determine whether there was a statistically significant difference in the mean rCBV and rMTE ratios between benign and malignant meningiomas. RESULTS: The mean maximal rCBV values of benign and malignant meningiomas were 7.16+/-4.08 (mean+/-SD) and 5.89+/-3.86, respectively, in the parenchyma, and 1.05+/-0.96 and 3.82+/-1.39, respectively, in the peritumoral edema. The mean rMTE values were 1.16+/-0.24 and 1.30+/-0.32, respectively, in the parenchyma, and 0.91+/-0.25 and 1.24+/-0.35, respectively, in the peritumoral edema. The differences in rCBV and rMTE values between benign and malignant meningiomas were not statistically significant (P>0.05) in the parenchyma, but both were statistically significant (P<0.05) in the peritumoral edema. CONCLUSION: Perfusion MR imaging can provide useful information on meningioma vascularity which is not available from conventional MRI. Measurement of maximal rCBV and corresponding rMTE values in the peritumoral edema is useful in the preoperative differentiation between benign and malignant meningiomas.

Workstation scheme and implementation for a medical imaging information system.

OBJECTIVE: To discuss the scheme and implementation of workstation configuration for medical imaging information systems suitable to the practical situation in China. METHODS: The workstations were logically divided into picture archiving and communication system (PACS) workstations and radiology information system (RIS) workstations. The former applied to three kinds of diagnostic practice: the small matrix images, large matrix images and high resolution grayscale display applications. The latter consisted many different models defined by the usage and function processes. RESULTS: A dual-screen configuration for image interpretation workstations integrated the image-viewing and reporting procedures physically. Small matrix images as CT or MR were operated on 17 inch (1 inch = 2.54 cm) color monitors, while conventional X-ray interpretation was performed on 21 inch color monitors or portrait format grayscale 2 k by 2.5 k monitors. All other RIS workstations not involved in imaging process were set up with a common PC configuration. CONCLUSION: Workstation schemes for medical imaging information systems should satisfy the basic requirements of medical imaging and investment budget.

[CT and MRI findings of cancerous invasion of the main pulmonary artery in lung cancer: the correlation with pathologic features and the value in making surgical plan].

BACKGROUND: To study the correlation between CT/MRI features and surgical and pathological findings of cancerous invasion of the main pulmonary artery (CIMPA) in lung cancer and to evaluate the role of CT and MRI in making surgical plan. METHODS: CT findings in 15 cases and MRI findings in 13 cases were observed and blindly compared with surgical and pathological findings in this prospective study of 23 cases of central type lung cancer. RESULTS: The CT and MRI features showed as follows: the wall thickening sign in 73.7% of CT and 84.6% of MRI; lumen narrowing sign in 55.3% of CT and 69.2% of MRI; peri-vascular fat sign in 100.0% of both CT and MRI. Two types of CIMPA were visualized: contacted type (10 cases in CT and 7 cases in MRI) and encased type (5 cases in CT and 6 cases in MRI). Surgically, contacted type was found in 10 cases who all underwent lobectomy with sleeve-angioplasty. Encased type was found in 13 cases, among whom unresectable in 2, pneumonectomy in 7, and lobectomy with angioplasty in 4. Of the 21 resected specimen, the cancerous infiltration was demonstrated 100.0% (21/21) in adventitia, 66.7% (14/21) in media and 4.8% (1/21) in intima. There was no significant difference in the deepness of the cancer infiltration between the two types (P>0.05). Acute or chronic inflammatory infiltration which enhanced the thickening of the wall were shown on all specimens. CT and MRI findings were well corresponding to surgical and pathological appearance (Kappa value = 0.61 in CT and 0.84 in MRI). CONCLUSIONS: In our study of CIMPA, CT and MRI features characterized by wall thickening and lumen narrowing without occlusion are closely correlated with pathological findings that cancerous invasion prominently limited adventitia and media with remarkable proliferation of connective tissue, and classifying two types is valuable in making surgical plan.

[The value of MR dynamic time-resolved subtracted imaging in evaluating the blood supply by systemic artery in patients with lung cancer].

BACKGROUND: To explore the application value of MR dynamic time-resolved subtracted imaging in qualitative and quantitative assessment of blood supply by systemic artery in patients with lung cancer. METHODS: A prospective study using MR FSPGR pulse sequence dynamic scan after contrast enhancement was undertaken in fifty-one patients with lung cancer which were proved by cytology or/and histology. The time-resolved subtracted imaging were acquired using the pre- and post-enhanced images in different phases of pulmonary circulation during the first-pass period (FPP) of contrast agent. The time-signal curves of FPP at four ROI placed on pulmonary artery (PA), descending aorta (DA), mass (M) and contralateral pulmonary parenchyma (PP), and the ST (start-time) and PT (peak-time) of those four ROI were measured. The enhancement ratio of the signals of M/PP at PA/DA peak time (E MP , E MA , E PP , E PA ) were calculated. RESULTS: According to the time-resolved subtracted imaging during PA phase, intensity of the signal was low in 7 cases, medium in 2, but not enhanced in other 42 cases. All the 51 cancer masses were remarkably enhanced during DA phase. During FPP, the ST [(5.90±0.51)s] and PT [(12.75±0.67)s] of PP were slightly later than the ST [(4.19±0.43)s] and PT [(10.59±0.66)s] of PA, while the ST [(11.03±0.80)s] and PT [(33.62±3.06)s] of cancer masses were later than ST [(9.43±0.59)s] and PT [(19.81±4.14)s] of DA. E MA was significantly higher than E MP (91.47%±18.83% vs 15.38%±11.03%, P < 0.001), while E PP were remarkably higher than E PA (273.83%±48.60% vs 140.65%±24.40%, P < 0.001). CONCLUSIONS: MR dynamic time-resolved subtracted imaging is feasible to be a non-invasive technique in qualitative and relatively quantitative assessment of blood supply by systemic artery in patients with lung cancer.

[A preliminary application of MR dynamic time-resolved subtracted perfusion imaging to qualitative and partial quantitative evaluation of the blood supply by pulmonary artery in peripheral type lung cancer].

BACKGROUND: To explore the application of MR time-resolved subtracted perfusion imaging to qualitatively and partially quantitatively evaluate blood supply by pulmonary artery in patients with peripheral type lung cancer. METHODS: Twenty-three patients with peripheral type lung cancer proved cytologically or/and histologically underwent MR perfusion study. The time-resolved subtracted imaging which provided the perfusion images in different phases were performed. First-pass time-signal intensity curves of pulmonary artery, descending aorta, lung mass were obtained respectively, and start-time and peak-time of them were compared. The signal enhanced ratio of the masses in pulmonary artery and aorta perfusion phases were calculated respectively. RESULTS: Fourteen masses began to enhance during pulmonary circulation phase and reached peak value during systematic-circulation phase, and the average signal change ratio during pulmonary circulation phase was much smaller than that during systematic-circulation phase, indicating their blood supply came both from pulmonary and systematic blood circulation, but mainly from the latter. Seven masses began to enhance and reached peak value during systematic-circulation phase, indicating their blood supply came mainly from systematic blood circulation. Two masses began to enhance and reached peak value during pulmonary-circulation phase, indicating their blood supply came mainly from pulmonary blood circulation. CONCLUSIONS: MR dynamic time-resolved subtracted perfusion imaging is feasible to qualitatively and relatively quantitatively evaluate blood supply of pulmonary artery for peripheral type lung cancer.

[CT features and anatomic distribution of pleural dissemination in lung cancer].

BACKGROUND: To study the CT appearance of lung cancer combined with pleural dissemination and its anatomic characteristics. METHODS: CT findings of 32 cases of lung cancer with pleural dissemination proved by surgery and pathology were analyzed. RESULTS: The main CT manifestations were pleural effusion (24 cases), visceral pleural dissemination with nodules (10 cases), parietal pleural dissemination with nodules (16 cases), and pleural thickening (31 cases). Out of the cases with visceral pleural disseminations, nodules distributed on the lung surface in 9 sites, while on the interlobular pleura in 10 sites. Parietal pleural dissemination with nodules were found in 45 sites which located on the diaphragmatic pleura, the costal pleura, the mediastinal pleura, and the pulmonary ligament. The diameters of the small nodules ranged from 2 to 5 mm, and the large nodules from 5 to 10 mm. There were direct invasion with tumor induced pleural thickening in 10 cases, while indirect invasion in 21 cases. In the later cases, 9 cases had parietal pleural thickening less than 10 mm, 4 circumferential pleural thickening, 5 mediastinal pleural involvement thickening, and 3 pulmonary ligament thickening. CONCLUSIONS: Pleural effusion is the main manifestation of lung cancer combined with pleural dissemination. The CT features of lung cancer with pleural dissemination are the parietal and visceral pleural nodules, as well as the pleural thickening. The nodules are likely to distribute on parietal pleura of the diaphragmatic and the costal pleura, and they may transfer to the pulmonary ligament.The early small disseminating nodules are miliary in size, and only can be detected on the pulmonary window of chest CT scan.