Evaluation of early tissue reactions after lumbar intertransverse process fusion using CT in a rabbit

OBJECTIVE: The objective of the study was to evaluate tissue reactions such as bone genesis, cartilage genesis and graft materials in the early phase of lumbar intertransverse process fusion in a rabbit model using computed tomography (CT) imaging with CT intensity (Hounsfield units) measurement, and to compare these data with histological results. MATERIALS AND METHODS: Lumbar intertransverse process fusion was performed on 18 rabbits. Four graft materials were used: autograft bone (n = 3); collagen membrane soaked with recombinant human bone morphogenetic protein-2 (rhBMP-2) (n = 5); granular calcium phosphate (n = 5); and granular calcium phosphate coated with rhBMP-2 (n = 5). All rabbits were euthanized 3 weeks post-operatively and lumbar spines were removed for CT imaging and histological examination. RESULTS: Computed tomography imaging demonstrated that each fusion mass component had the appropriate CT intensity range. CT also showed the different distributions and intensities of bone genesis in the fusion masses between the groups. Each component of tissue reactions was identified successfully on CT images using the CT intensity difference. Using CT color mapping, these observations could be easily visualized, and the results correlated well with histological findings. CONCLUSIONS: The use of CT intensity is an effective approach for observing and comparing early tissue reactions such as newly synthesized bone, newly synthesized cartilage, and graft materials after lumbar intertransverse process fusion in a rabbit model.

Correlation of intravascular ultrasound findings with histopathological analysis of thrombus aspirates in patients with very late drug-eluting stent thrombosis

BACKGROUND: Intravascular ultrasound of drug-eluting stent (DES) thrombosis (ST) reveals a high incidence of incomplete stent apposition (ISA) and vessel remodeling. Autopsy specimens of DES ST show delayed healing and hypersensitivity reactions. The present study sought to correlate histopathology of thrombus aspirates with intravascular ultrasound findings in patients with very late DES ST. METHODS AND RESULTS: The study population consisted of 54 patients (28 patients with very late DES ST and 26 controls). Of 28 patients with very late DES ST, 10 patients (1020+/-283 days after implantation) with 11 ST segments (5 sirolimus-eluting stents, 5 paclitaxel-eluting stents, 1 zotarolimus-eluting stent) underwent both thrombus aspiration and intravascular ultrasound investigation. ISA was present in 73% of cases with an ISA cross-sectional area of 6.2+/-2.4 mm(2) and evidence of vessel remodeling (index, 1.6+/-0.3). Histopathological analysis showed pieces of fresh thrombus with inflammatory cell infiltrates (DES, 263+/-149 white blood cells per high-power field) and eosinophils (DES, 20+/-24 eosinophils per high-power field; sirolimus-eluting stents, 34+/-28; paclitaxel-eluting stents, 6+/-6; P for sirolimus-eluting stents versus paclitaxel-eluting stents=0.09). The mean number of eosinophils per high-power field was higher in specimens from very late DES ST (20+/-24) than in those from spontaneous acute myocardial infarction (7+/-10), early bare-metal stent ST (1+/-1), early DES ST (1+/-2), and late bare-metal stent ST (2+/-3; P from ANOVA=0.038). Eosinophil count correlated with ISA cross-sectional area, with an average increase of 5.4 eosinophils per high-power field per 1-mm(2) increase in ISA cross-sectional area. CONCLUSIONS: Very late DES thrombosis is associated with histopathological signs of inflammation and intravascular ultrasound evidence of vessel remodeling. Compared with other causes of myocardial infarction, eosinophilic infiltrates are more common in thrombi harvested from very late DES thrombosis, particularly in sirolimus-eluting stents, and correlate with the extent of stent malapposition.

Early- and long-term intravascular ultrasound and angiographic findings after bioabsorbable magnesium stent implantation in human coronary arteries

OBJECTIVES: This study aimed to evaluate the degradation rate and long-term vascular responses to the absorbable metal stent (AMS). BACKGROUND: The AMS demonstrated feasibility and safety at 4 months in human coronary arteries. METHODS: The PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting) was a prospective, multicenter clinical trial of 63 patients with coronary artery disease who underwent AMS implantation. Angiography and intravascular ultrasound (IVUS) were conducted immediately after AMS deployment and at 4 months. Eight patients who did not require repeat revascularization at 4 months underwent late angiographic and IVUS follow-up from 12 to 28 months. RESULTS: The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 +/- 5.2 mm(3), with an increase in the stent cross sectional area of 0.5 +/- 1.0 mm(2) (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up. CONCLUSIONS: Intravascular ultrasound imaging supports the safety profile of AMS with degradation at 4 months and maintains durability of the results without any early or late adverse findings. Slower degradation is warranted to provide sufficient radial force to improve long-term patency rates of the AMS.

Dissection of the Appendix with Ultrasound-Activated Scalpel: An Experimental Study in Pediatric Laparoscopic Appendectomy

Abstract Background: The aim of this study was to examine mechanical, microbiologic, and morphologic changes of the appendicle rim to assess if it is appropriate to dissect the appendix with the ultrasound-activated scalpel (UAS) during laparoscopic appendectomy. Materials and Methods: After laparoscopic resection of the appendix, using conventional Roeder slings, we investigated 50 appendicle rims with an in vitro procedure. The overall time of dissection of the mesoappendix with UAS was noted. Following removal, the appendix was dissected in vitro with the UAS one cme from the resection rim. Seal-burst pressures were recorded. Bacterial cultures of the UAS-resected rim were compared with those of the scissors resected rim. Tissue changes were quantified histologically with hematoxylin and eosin (HE) stains. Results: The average time to dissect the mesoappendix was 228 seconds (25-900). Bacterial culture growths were less in the UAS-resected probes (7 versus 36 positive probes; (p > 0.01). HE-stained tissues revealed mean histologic changes in the lamina propria muscularis externa of 2 mm depth. The seal-burst pressure levels of the appendicle lumen had a mean of 420 mbar. Seal-burst pressures and depths of histologic changes were not dependent on the different stages of appendicitis investigated, gender, or age groups. Seal-burst pressure levels were not related to different depths of tissue changes (P = 0.64). Conclusions: The UAS is a rapid instrument for laparoscopic appendectomy and appears to be safe with respect to stability, sterility and tissue changes. It avoids complex time consuming instrument change manoeuvres and current transmission, which may induce intra- and postoperative complications. Our results suggest that keeping a safety margin of at least 5 mm from the bowel would be sufficient to avoid thermal damage.

[ECG-gated chest CT angiography: value for atypical chest pain evaluation]

PURPOSE: The aim of this study was to evaluate ECG-gated whole chest CTA as a routine triage tool for patients with acute chest pain. MATERIAL AND METHODS: Whole chest CTA with retrospective ECG-gating was performed in 30 patients with acute atypical chest pain. The ten main segments of the coronary arteries, the pulmonary arteries, the aorta, and the myocardium (function, morphology) were independently analyzed by a resident and two senior radiologists. The inter-observer agreement between resident and senior radiologists was calculated. A final diagnosis was determined by consensus. RESULTS: Thirty patients were included. The coronary artery segments, myocardium and pulmonary arteries were considered analyzable in 84%, 90% and 97% of cases respectively. A final diagnosis for the cause of pain was retained in 19 patients: significant coronary artery stenosis (5), pulmonary embolus (5), aortic dissection (1), hypokinetic cardiomyopathy (2), lung parenchymal abnormalities (5), and hiatus hernia (1). Inter-observer agreement ranged from 0.76 to 1 between senior radiologists and from 0.76 to 1 between resident and senior radiologists. The average time of image interpretation ranged from 14 to 15 minutes. CONCLUSION: ECG-gated whole chest CT angiography appears as a promising tool for the evaluation of acute chest pain. Combined evaluation of appearance and function of the myocardium can reveal additional interesting information.

A comparison of frontal radiographs obtained from cone beam CT scans and conventional frontal radiographs of human skulls

This study evaluated whether measurements on conventional frontal radiographs are comparable with measurements on cone beam computed tomography (CBCT)-constructed frontal cephalometric radiographs taken from dry human skulls. CBCT scans and conventional frontal cephalometric radiographs were made of 40 dry skulls. With I-Cat Vision((R)) software, a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks and calculate ratios and angles. The same operator identified 10 landmarks on both types of cephalometric radiographs on all Images 5 times with a time-interval of 1 week. Intra-observer reliability was acceptable for all measurements. The reproducibility of the measurements on the frontal radiographs obtained from the CBCT scans was higher than those on conventional frontal radiographs. There is a statistically significant and clinically relevant difference between measurements on conventional and constructed frontal radiographs. There is a clinically relevant difference between angular measurements performed on conventional frontal cephalometric radiographs, compared with measurements on frontal cephalometric radiographs constructed from CBCT scans, owing to different positioning of patients in both devices. Positioning of the patient in the CBCT device appears to be an important factor in cases where a 2D projection of the 3D scan is made.

Quantitative assessment of oral orbicular muscle deformation after cleft lip reconstruction: an ultrasound elastography study

Reconstruction of a cleft lip leads inevitably to scar tissue formation. Scar tissue within the restored oral orbicular muscle might be assessed by quantification of the local contractility of this muscle. Furthermore, information about the contraction capability of the oral orbicular muscle is crucial for planning the revision surgery of an individual patient. We used ultrasound elastography to determine the local deformation (strain) of the upper lip and to differentiate contracting muscle from passive scar tissue. Raw ultrasound data (radio-frequency format; rf-) were acquired, while the lips were brought from normal state into a pout condition and back in normal state, in three patients and three normal individuals. During this movement, the oral orbicular muscle contracts and, consequently, thickens in contrast to scar tissue that will not contract, or even expand. An iterative coarse-to-fine strain estimation method was used to calculate the local tissue strain. Analysis of the raw ultrasound data allows estimation of tissue strain with a high precision. The minimum strain that can be assessed reproducibly is 0.1%. In normal individuals, strain of the orbicular oral muscle was in the order of 20%. Also, a uniform strain distribution in the oral orbicular muscle was found. However, in patients deviating values were found in the region of the reconstruction and the muscle tissue surrounding that. In two patients with a successful reconstruction, strain was reduced by 6% in the reconstructed region with respect to the normal parts of the muscle (from 22% to 16% and from 25% to 19%). In a patient with severe aesthetical and functional disability, strain decreased from 30% in the normal region to 5% in the reconstructed region. With ultrasound elastography, the strain of the oral orbicular muscle can be quantified. In healthy subjects, the strain profiles and maximum strain values in all parts of the muscle were similar. The maximum strain of the muscle during pout was 20% +/- 1%. In surgically repaired cleft lips, decreased deformation was observed.

Minimal local anesthetic volume for peripheral nerve block: a new ultrasound-guided, nerve dimension-based method

BACKGROUND AND OBJECTIVES: Nerve blocks using local anesthetics are widely used. High volumes are usually injected, which may predispose patients to associated adverse events. Introduction of ultrasound guidance facilitates the reduction of volume, but the minimal effective volume is unknown. In this study, we estimated the 50% effective dose (ED50) and 95% effective dose (ED95) volume of 1% mepivacaine relative to the cross-sectional area of the nerve for an adequate sensory block. METHODS: To reduce the number of healthy volunteers, we used a volume reduction protocol using the up-and-down procedure according to the Dixon average method. The ulnar nerve was scanned at the proximal forearm, and the cross-sectional area was measured by ultrasound. In the first volunteer, a volume of 0.4 mL/mm of nerve cross-sectional area was injected under ultrasound guidance in close proximity to and around the nerve using a multiple injection technique. The volume in the next volunteer was reduced by 0.04 mL/mm in case of complete blockade and augmented by the same amount in case of incomplete sensory blockade within 20 mins. After 3 up-and-down cycles, ED50 and ED95 were estimated. Volunteers and physicians performing the block were blinded to the volume used. RESULTS: A total 17 of volunteers were investigated. The ED50 volume was 0.08 mL/mm (SD, 0.01 mL/mm), and the ED95 volume was 0.11 mL/mm (SD, 0.03 mL/mm). The mean cross-sectional area of the nerves was 6.2 mm (1.0 mm). CONCLUSIONS: Based on the ultrasound measured cross-sectional area and using ultrasound guidance, a mean volume of 0.7 mL represents the ED95 dose of 1% mepivacaine to block the ulnar nerve at the proximal forearm.