P5637A novel bioresorbable magnesium-based stent: initial clinical results and 6-months follow-up by coronary computed tomography angiography scan

Background

Drug-eluting stents (DES) are the gold standard in percutaneous coronary interventions (PCI), but leave a permanent metallic “caging” of the treated vessels limiting further assessment of in-stent lumen patency by coronary computed tomography angiography (CCTA) due to artifacts. Absorbable scaffolds were designed to overcome the caging limitation but the first generation made of poly-L-lactic acid demonstrated higher thrombosis rates. A novel bioresorbable magnesium-based (Mg-)stent coated with a biodegradable polymer eluting sirolimus has been developed, with promising results in the BIOSOLVEII-III studies.

Aim

We sought to characterize PCI results by CCTA at 6-mo follow-up of patients treated with at least one Mg-stent in our institution.

Methods

Prospective observational registry started since January 2017 of younger patients with de novo lesions preferably treated with Mg-stents after balloon pre-dilatation. Procedural data and major adverse clinical events (MACE) at hospital discharge and 6-mo follow-up were collected. Reference vessel and in-stent minimal lumen area were measured on a CCTA performed at 6-mo.

Results

34 Mg-stents (mean diameter: 3.2±0.2 mm, length 21.3±4.1 mm) were successfully implanted in 29 patients (mean age 54±6 years with male:female ratio 3:1). Acute coronary syndrome was the presenting diagnosis in 76% (n=22) with STEMI in 31% (n=9). The left anterior descending artery was treated in 62% (n=21). Calcifications on angiography were found in 14 lesions (41%). Intravascular imaging was performed in 3 PCI. With CCTA at 7.1±3.5 months (n=15 up to date, ongoing further follow-up to be presented), proximal and distal stent markers were well visualized while scaffold struts were not discernible. Mean proximal and distal reference lumen area were respectively 8.5±4.2 mm2 and 6.1±2.8 mm2. Mean in-stent minimal lumen area (MLA) was 6.3±2.9 mm2, with no statistical difference with the mean of the proximal and distal references (7.3±3.3 mm2, p=0.155, Wilcoxon rank test) demonstrating minimal instent hyperplasia at 6-mo: significant in-stent restenosis was noted in only one patient who remains so far asymptomatic (MLA 1.1 mm2; reference vessel lumen area 5.5 mm2). CCTA were non interpretable in 2 patients due to artifacts unrelated to the Mg-stents. One death secondary to a complicated cardiac tamponade was reported. No further MACE at 6-mo were noted.

CCTA cross sectional cut

Conclusion

6-mo CCTA of patients treated with a Mg-stent are fully interpretable to detect in-stent restenosis, without blooming artifacts. Accurate non-invasive assessment of the late results of our monocentric observational registry demonstrated 1 asymptomatic instent restenosis in 34 Mg-stents (3%) and overall optimal stent deployment and late artery patency, achieved with only 1 MACE in 29 patients (3.4%). This highlights the potentials of this new Mg-bioresorbable stent and the use of CCTA for clinical follow-up of the treated patients.

Prognostic factors to succeed in surgical treatment of chronic acromioclavicular dislocations

INTRODUCTION

Treatment of chronic acromioclavicular joint dislocation (ACJD) remains a poorly known and controversial subject. Given the many surgical options, it is not always easy to determine which steps are indispensable.

METHODS

This article reports a multicenter prospective study. The clinical and radiological follow-up involved a comparative analysis of the preoperative and postoperative data at 1 year, including pain (visual analogue scale), subjective functional incapacity (QuickDASH), and the objective Constant score, as well as a comparative analysis of vertical and horizontal movements measured on simple x-rays.

RESULTS

Based on a series of 140 operated ACJDs, we included 24 chronic ACJDs. The mean time to surgery was 46 weeks (range, 1 month to 4 years). The patients' mean age was 41 years, with a majority of males (75%), 72% of whom participated in recreational sports. Professionally, 40% of the subjects had jobs involving manual labor. We noted 40% grade III, 24% grade IV, and 36% grade V injury according to the Rockwood classification. In 92% of cases, coracoclavicular stabilization was provided by a double button implant, reinforced with a biological graft in 88% of the cases. In 29%, millimeters to centimeters of the distal clavicle were resected and acromioclavicular stabilization was associated in 54%. We observed complications in 33% of the cases. At 1 year postoperative, 21 patients underwent clinical and radiological follow-up (87.5%). Only 35% of the patients were satisfied or very satisfied, whereas 100% of them would recommend the operation. Full-time work was resumed in 91% of the cases and all sports could be resumed in 86%. The pre- and postoperative values at 1 year changed as follows: the mean Constant score improved from 61 to 87 (p=0.00002); the subjective QuickDASH score decreased from 41 to 9 (p=0.00002); and radiologically significant reduction of the initial displacement was observed in the vertical plane (p<10(-3)) and the horizontal plane (p=0.022).

CONCLUSION

In this study, the favorable prognostic factors found were: time to surgery less than 3 months (p=0.02), associated acromioclavicular stabilization, and postoperative immobilization with a sling extended to 6 weeks. However, resection of the distal clavicle did not influence the final result.

LEVEL OF PROOF

Level II prospective non-randomized comparative study.

Is coracoclavicular stabilisation alone sufficient for the endoscopic treatment of severe acromioclavicular joint dislocation (Rockwood types III, IV, and V)?

BACKGROUND

The primary objective was to evaluate correlations linking anatomical to functional outcomes after endoscopically assisted repair of acute acromioclavicular joint dislocation (ACJD).

HYPOTHESIS

Combined acromioclavicular and coracoclavicular stabilisation improves radiological outcomes compared to coracoclavicular stabilisation alone.

MATERIAL AND METHODS

A prospective multicentre study was performed. Clinical outcome measures were pain intensity on a visual analogue scale (VAS), subjective functional impairment (QuickDASH score), and Constant's score. Anatomical outcomes were assessed on standard radiographs (anteroposterior view of the acromioclavicular girdle and bilateral axillary views) obtained preoperatively and postoperatively and on postoperative dynamic radiographs taken as described by Tauber et al.

RESULTS

Of 116 patients with acute ACJD included in the study, 48% had type III, 30% type IV, and 22% type V ACJD according to the Rockwood classification. Coracoclavicular stabilisation was achieved using a double endobutton in 93% of patients, and concomitant acromioclavicular stabilisation was performed in 50% of patients. The objective functional outcome was good, with an unweighted Constant's score ≥ 85/100 and a subjective QuickDASH functional disability score ≤ 10 in 75% of patients. The radiographic analysis showed significant improvements from the preoperative to the 1-year postoperative values in the vertical plane (decrease in the coracoclavicular ratio from 214 to 128%, p=10(-6)) and in the horizontal plane (decrease in posterior displacement from 4 to 0mm, p=5×10(-5)). The anatomical outcome correlated significantly with the functional outcome (absolute R value=0.19 and p=0.045). We found no statistically significant differences across the various types of constructs used. Intra-operative control of the acromioclavicular joint did not improve the result. Implantation of a biological graft significantly improved both the anatomical outcome in the vertical plane (p=0.04) and acromioclavicular stabilisation in the horizontal plane (p=0.02). The coracoclavicular ratio on the anteroposterior radiograph was adversely affected by a longer time from injury to surgery (p=0.02) and by a higher body mass index (BMI) (p=0.006). High BMI also had a negative effect on the difference in the distance separating the anterior edge of the acromion from the anterior edge of the clavicle between the injured and uninjured sides, as assessed on the axillary views (p=0.009).

CONCLUSION

This study demonstrates that acute ACJD requires stabilisation in both planes, i.e., at the coracoclavicular junction and at the acromioclavicular joint. Coracoclavicular stabilisation alone is not sufficient, regardless of the type of implant used. Implantation of a biological graft should be considered when the time from injury to surgery is longer than 10days. The weight of the upper limb should be taken into account, with 6weeks of immobilisation to unload the construct in patients who have high BMI values.

LEVEL OF EVIDENCE

II, prospective non-randomised comparative study.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis

OBJECTIVE

To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT.

METHODS

This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used.

RESULTS

46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M.

CONCLUSION

Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis.

ADVANCES IN KNOWLEDGE

In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.

Can we improve radiological analysis of osseous lesions in chronic anterior shoulder instability?

Osseous lesions of the glenoid cavity and humeral head are predictive of recurrence after Bankart arthroscopic procedures. The objective of this study was to analyze, for each glenoid and humeral defect plain x-ray criteria of the Instability Severity Index Score (ISIS), two aspects: inter- and intraobserver reliability of their qualitative and quantitative assessment and correlations between positive criteria and their quantitative measurement. Thirty-one medical files were retained for evaluation of the glenoid and 26 for humeral notch assessment. The yes or no response for the ISIS criterion was completed by its quantitative measurement using the Griffiths and Sugaya CT methods for the glenoid and the P/R index calculation on plain x-rays with internal rotation for the Hill-Sachs lesion. Three observers provided two consecutive readings for each criterion. The analysis of the glenoid radiological criterion of the ISIS seems sufficiently reproducible for daily practice. When the evaluation is positive, bone loss is greater than 15%, without a maximum value established. In this study, the analysis of the ISIS humeral notch criterion was not reproducible. It can be improved using the P/R index and should be completed by CT imaging.

Réparation arthroscopique des ruptures transfixiantes de la coiffe

PURPOSE OF THE STUDY

Totally arthroscopic repair of rotator cuff tears is now common practice. The techniques used were evaluated by a retrospective multicentric analysis conducted by the French Society of Arthroscopy.

MATERIAL AND METHODS

The series was limited to arthroscopic repair of full thickness tears of the supraspinatus or infraspinatus evaluated using the Constant score and arthro-MRI or arthroscan performed with at least one year follow-up. Data were processed with SPSS 10. The series included 576 patients who underwent surgery between January 2001 and June 2003. Mean patient age was 57.7 years; 52% were men and 60% were manual laborers. The mean preoperative Constant score was 46.4 +/- 13.4/100. The tear was limited to the supraspinatus in 69% of shoulders, with extension to the upper third of the infraspinatus in 23.5% and the entire infraspinatus in 7.5%. The supraspinatus tear was distal in 41.7% of shoulders, intermediary in 44% and retracted in 14.3%. Fatty degeneration of the supraspinatus was noted grade 0 in 60%, 1 in 27%, 2 in 11% and 3 in 2%. Arthroscopic repair was performed in all cases, with locoregional anesthesia in 60.9%. Bioresorbable implants were used in 33% and metallic implants in 62.1%. Acromioplasty was performed in 92.7% and capsulotomy in 14.9%.

RESULTS

On average, the subjective outcome was scored 8.89/10. The Constant score improved from 46.3 +/- 13.4 to 82.7 +/- 10.3 with 62% having a strictly pain free shoulder. Muscle force improved from 5.8 +/- 3.7 to 13.6 +/- 5.4. Outcome was excellent in 94% of shoulders at 18.5 months mean follow-up. The complication rate in this series was 6.2% with 3.1% prolonged stiffness, 2.7% reflex dystrophy, 0.2% infection, and 0.2% anchor migration. The cuff was considered normal in 55.7% of shoulders with an intratendon addition image in 19%, i.e. 74.7% of non-ruptured cuffs. Minimal loss of integrity was noted in 9.5% and was marked in 15.7%, i.e. 25.2% iterative tears.ANATOMOCLINICAL CORRELATIONS: The Constant score was strongly correlated with rotator cuff integrity (p<0001). This correlation was also found for force (p<0001), motion (0.01) and activity (0.04), but not for pain. The clinical outcome was correlated with extension, retraction, intrasubstance tear, and fatty degeneration of the lesion preoperatively. Anatomic results were statistically less favorable for tears which were older, extensive, retracted or associated with fatty degeneration. Age was correlated with extent of the initial tear and also with less favorable anatomic and clinical outcome. Occupational accidents were correlated with less favorable clinical outcome.

CONCLUSION

Functional improvement after healing is a strong argument for repair. Arthroscopy has the advantage of combining a low complication rate with good clinical and anatomic results. Age is correlated with functional outcome and healing, but is not a contraindication.

Three-dimensional anatomy of the hip in osteoarthritis after developmental dysplasia

Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV.

The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT.

The results of our study confirm the observations previously confined to the Japanese population.

Boron neutron capture enhancement (BNCE) of fast neutron irradiation for glioblastoma: increase of thermal neutron flux with heavy material collimation, a theoretical evaluation

Despite the fact that fast neutron irradiation of glioblastoma has shown on autopsies an ability to sterilize tumors, no therapeutic windows have been found for these particles due to their toxicity toward normal brain. Therefore, the Boron Neutron Capture Enhancement (BNCE) of fast neutron beam has been suggested. This paper addresses the problem of fast neutron beam collimation, which induces a dramatic decrease of the thermal neutron flux in the depth of the tissues when smaller irradiation fields are used. Thermoluminescent dosimeter TLD-600 and TLD-700 were used to determine the thermal neutron flux within a Plexiglas phantom irradiated under the Nice Biomedical Cyclotron p(60)+Be(32) fast neutron beam. A BNCE of 4.6% in physical dose was determined for a 10 x 10 cm2 field, and of 10.4% for a 20 x 20 cm2 one. A Dose Modification Factor of 1.19 was calculated for CAL 58 glioblastoma cells irradiated thanks to the larger field. In order to increase the thermal flux in depth while shaping the beam, heavy material collimation was studied with Monte Carlo simulations using coupled FLUKA and MCNP-4A codes. The use of 20 cm width lead blocks allowed a 2 fold thermal neutron flux increase in the depth of the phantom, while shielding the fast neutron beam with a fast neutron dose transmission of 23%. Using the DMF of 1.19, a BNCE of 40% was calculated in the beam axis. This enhancement might be sufficient to open, at least theoretically, a therapeutic window.

Combined use of FLUKA and MCNP-4A for the Monte Carlo simulation of the dosimetry of 10B neutron capture enhancement of fast neutron irradiations

Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on 10B within tumor cells. The dose enhancement is correlated to the 10B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP-4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD-600 and TLD-700, respectively, doped with 6Li or 7Li). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at 10.3 X 10(6) n/cm2 s1 and measured at 9.42 X 10(6) n/cm2 s1 at 4 cm depth of the phantom and with a 10 cm X 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build-up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm X 10 cm or 20 cm X 20 cm fields, provided that 100 micrograms/g of 10B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications.

Proton beam dosimetry: a comparison between the Faraday cup and an ionization chamber

From the theoretical point of view, the Faraday cup (FC) is an absolute instrument for fluence measurements of proton beams. As the FC is easily manufactured it can be considered an 'in-house' calibration system. Moreover, at the moment no national standards for proton dosimetry are available. Up to now the experimental tests of these instruments show that much study still has to be done to better understand their use in reference dosimetry. To investigate the possibility of using an FC as a secondary standard, an FC was jointly designed by the 'TERA Collaboration' and 'Centre Antoine-Lacassagne' (Nice, France) to evaluate the main parameters of the instrument. A comparison between two FCs of different designs--the 'TERA FC' and the 'Nice FC'--and an ionization chamber (IC) used for routine proton dosimetry was carried out. Results show that the two FCs agree to within 1.5-3.6%. While the differences between FC and IC are larger--6% for the 'TERA FC' and 8.2% for the 'Nice FC', the FC giving a lower dose evaluation--they follow the same trend shown by the calorimetric measurements. The data show that once the beam characteristics are defined, the fluence measurements are reproducible and show a good accuracy.

RBE variation between fast neutron beams as a function of energy. Intercomparison involving 7 neutrontherapy facilities

In fast neutron therapy, the relative biological effectiveness (RBE) of a given beam varies to a large extent with the neutron energy spectrum. This spectrum depends primarily on the energy of the incident particles and on the nuclear reaction used for neutron production. However, it also depends on other factors which are specific to the local facility, eg, target, collimation system, etc. Therefore direct radiobiological intercomparisons are justified. The present paper reports the results of an intercomparison performed at seven neutrontherapy centres: Orléans, France (p(34)+Be), Riyadh, Saudi Arabia (p(26)+Be), Ghent, Belgium (d(14.5)+Be), Faure, South Africa (p(66)+Be), Detroit, USA (d(48)+Be), Nice, France (p(65)+Be) and Louvain-la-Neuve, Belgium (p(65)+Be). The selected radiobiological system was intestinal crypt regeneration in mice after single fraction irradiation. The observed RBE values (ref cobalt-60 gamma-rays) were 1.79 +/- 0.10, 1.84 +/- 0.07, 2.24 +/- 0.11, 1.55 +/- 0.04, 1.51 +/- 0.03, 1.50 +/- 0.04 and 1.52 +/- 0.04, respectively. When machine availability permitted, additional factors were studied: two vs one fraction (Ghent, Louvain-la-Neuve), dose rate (Detroit), influence of depth in phantom (Faure, Detroit, Nice, Louvain-la-Neuve). In addition, at Orléans and Ghent, RBEs were also determined for LD50 at 6 days after selective abdominal irradiation and were found to be equal to the RBEs for crypt regeneration. The radiobiological intercomparisons were always combined with direct dosimetric intercomparisons and, when possible in some centres, with microdosimetric investigations.

The RBE of fast neutrons for in vitro inactivation of human tumour cells determined by the ratio of mean inactivation doses

In an effort to clarify the relationship between sensitivity of human tumour cells to low-LET and to fast neutron irradiation, 10 human tumour cell lines were exposed to cobalt gamma-rays and to 60 MeV (p -> Be+) neutron beam. The data were pooled with results of 31 human tumour cell lines previously published. The analysis of date using the linear-quadratic model indicated that not only alpha values increased after neutron irradiation, but so did beta values too, although to a lesser extent. The mean inactivation dose (MID) was derived for each cell line from the linear-quadratic parameters after low-LET and high-LET exposure. MID values following neutron irradiation were closely correlated to those after gamma-ray irradiation. In these 41 cell lines, the extreme values of RBE derived by the ratio of MID varied by a factor of 3 among the cell lines. RBE was positively correlated to photon MID, meaning that intrinsically radiation resistant tumour cells have a higher neutron RBE, on average. Similar findings were observed if alpha ratios were used instead of MID ratios. In addition, the RBE/dose variations were more marked in cells with the higher RBE. Taken together, these data suggest that, although considerable variations exist among human tumour cell lines, intrinsically radioresistant cells are relatively more sensitized when exposed to high LET beams than radioresponsive tumours. An 'intrinsic gain factor' may thus be expected in irradiating radiation resistant tumours with fast neutrons, in addition to the hypoxic or kinetic gain factors. Because the quadratic component is still present after neutron irradiation, we suggest using MID ratio as a reference RBE when comparing survival curves of cells exposed to radiations of different qualities.

Changes in biological effectiveness with depth of the Medicyc neutron therapy beam

V79 cells were exposed to fast neutrons generated by 60 MeV p-->Be produced by the cyclotron Medicyc at four different depths: 1.3, 25.8, 72.2 and 116.8 mm. Survival was assessed by the in vitro colony method. Mean inactivation doses (MID) were significantly different among the four points. The ratio of MID was used to determine the relative efficiency of the neutron beam at these points. Compared to 25.8 mm depth, a 40% increase in biological effect was observed at the superficial point versus a 14 to 16% decrease in effect for the deeper points. This is ascribed to absorption of low energy neutrons near the surface and to beam hardening with depth. Taking in consideration the relative physical dose delivered, these findings suggest that skin-sparing may be markedly reduced and that the lower effectiveness with depth should be kept in mind when dealing with deep tumours.

The depth-dependent radiation response of human melanoma cells exposed to 65 MeV protons

Radiation therapy with positively charged particles implies that the Bragg peak be spread out to deliver a homogeneous dose to the tumour. The spread-out Bragg peak (SOBP) has a higher linear energy transfer (LET) than the entrance beam. In addition, there is an LET gradient from proximal to distal SOBP. The aim of this study is to find out whether these small LET variations lead to differences in radiation response. Human melanoma cells (CAL4) were exposed to 65 MeV proton beams produced by the cyclotron Medicyc at five different positions: 2 mm depth corresponding to the entrance, 15, 20, 25 and 26.8 mm depth corresponding to four different positions in the half-modulated SOBP. Survival curves were generated using the in vitro colony method and fitted with the linear-quadratic model. Survival differences were observed at high doses; they were statistically significant at a dose of 8 Gy. With respect to the entrance position (2 mm), the relative biological effectiveness (RBE) at 1% survival was 1.09, 1.12, 1.19 and 1.27 at 15, 20, 25 and 26.8 mm in the SOBP, respectively. Whereas RBE values in the SOBP greater than 1.0 relative to the entrance beam represent a small biological advantage to be added to the well-known physical advantage of high energy proton beams; the RBE gradient along the SOBP would imply that the distal end of the tumour would receive a higher biologically equivalent dose than the proximal end, despite a homogeneous physical dose, especially at the high doses per fraction given in ocular melanomas. Although the increase in effectiveness with depth is mild, it should be kept in mind during eye treatment planning, in case a critical target is present at the extreme end of the SOBP.

[The proton radiotherapy of melanoma of the uvea. The technic, methodology and first clinical observations]

Since June 1991, a Cyclotron unit with a proton beam of 65 MeV has been working at the Institute Antoine Lacassagne in Nice, France. An international cooperative group has been founded to guarantee the thorough exploitation of the facility through complete cooperation. From June 17 to December 20, 1991, 47 patients with uveal melanoma were treated; 4 of them entered the study by means of the Italian team and were treated in cooperation with the Cyclotron staff. Treatment modalities and preliminary observations are described.