A three-dimensional printing navigational template combined with mixed reality technique for localizing pulmonary nodules

OBJECTIVES Localizing non-palpable pulmonary nodules is challenging for thoracic surgeons. Here, we investigated the accuracy of three-dimensional (3D) printing technology combined with mixed reality (MR) for localizing ground glass opacity-dominant pulmonary nodules. METHODS In this single-arm study, we prospectively enrolled patients with small pulmonary nodules (<2 cm) that required accurate localization. A 3D-printing physical navigational template was designed based on the reconstruction of computed tomography images, and a 3D model was generated through the MR glasses. We set the deviation distance as the primary end point for efficacy evaluation. Clinicopathological and surgical data were obtained for further analysis. RESULTS Sixteen patients with 17 non-palpable pulmonary nodules were enrolled in this study. Sixteen nodules were localized successfully (16/17; 94.1%) using this novel approach with a median deviation of 9 mm. The mean time required for localization was 25 ± 5.2 min. For the nodules in the upper/middle and lower lobes, the median deviation was 6 mm (range, 0–12.0) and 16 mm (range, 15.0–20.0), respectively. The deviation difference between the groups was significant (Z = −2.957, P = 0.003). The pathological evaluation of resection margins was negative. CONCLUSIONS The 3D printing navigational template combined with MR can be a feasible approach for localizing pulmonary nodules.

Comparative Evaluation of Digitization of Diagnostic Dental Cast (Plaster) Models Using Different Scanning Technologies

Rapidly developing digital dental technologies have substantially simplified the documentation of plaster dental models. The large variety of available scanners with varying degrees of accuracy and cost, however, makes the purchase decision difficult. This study assessed the digitization accuracy of a cone-beam computed tomography (CBCT) and an intraoral scanner (IOS), as compared to a desktop optical scanner (OS). Ten plaster dental models were digitized three times (n = 30) with each scanner. The generated STL files were cross-compared, and the RMS values were calculated. Conclusions were drawn about the accuracy with respect to precision and trueness levels. The precision of the CBCT scanner was similar to the desktop OS reference, which both had a median deviation of 0.04 mm. The IOS had statistically significantly higher deviation compared to the reference OS, with a median deviation of 0.18 mm. The trueness values of the CBCT was also better than that of IOS—median differences of 0.14 and 0.17 mm, respectively. We conclude that the tested CBCT scanner is a highly accurate and user-friendly scanner for model digitization, and therefore a valuable alternative to the OS. The tested IOS was generally of lower accuracy, but it can still be used for plaster dental model digitization.

The endonasal patient reference tracker: a novel solution for accurate noninvasive electromagnetic neuronavigation

OBJECTIVEElectromagnetic (EM) navigation provides the advantages of continuous guidance and tip-tracking of instruments. The current solutions for patient reference trackers are suboptimal, as they are either invasively screwed to the bone or less accurate if attached to the skin. The authors present a novel EM reference method with the tracker rigidly but not invasively positioned inside the nasal cavity.METHODSThe nasal tracker (NT) consists of the EM coil array of the AxiEM tracker plugged into a nasal tamponade, which is then inserted into the inferior nasal meatus. Initially, a proof-of-concept study was performed on two cadaveric skull bases. The stability of the NT was assessed in simulated surgical situations, for example, prone, supine, and lateral patient positioning and skin traction. A deviation ≤ 2 mm was judged sufficiently accurate for clinical trial. Thus, a feasibility study was performed in the clinical setting. Positional changes of the NT and a standard skin-adhesive tracker (ST) relative to a ground-truth reference tracker were recorded throughout routine surgical procedures. The accuracy of the NT and ST was compared at different stages of surgery.RESULTSEx vivo, the NT proved to be highly stable in all simulated surgical situations (median deviation 0.4 mm, range 0.0–2.0 mm). In 13 routine clinical cases, the NT was significantly more stable than the ST (median deviation at procedure end 1.3 mm, range 0.5–3.0 mm vs 4.0 mm, range 1.2–11.2 mm, p = 0.002). The loss of accuracy of the ST was highest during draping and flap fixation.CONCLUSIONSApplication of the EM endonasal patient tracker was found to be feasible with high procedural stability ex vivo as well as in the clinical setting. This innovation combines the advantages of high precision and noninvasiveness and may, in the future, enhance EM navigation for neurosurgery.

Observations of meteors in the Earth’s atmosphere: Reducing data from dedicated double-station wide-angle cameras

Meteoroids entering the Earth’s atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The software package is designed to fully utilise the high photometric quality of SPOSH images. This will facilitate the detection of meteor streams and studies of their trajectories. We have run simulations to assess the performance of the software by estimating the radiants, speeds, and magnitudes of synthetic meteors and comparing them with the a priori values. The estimated uncertainties in radiant location had a zero mean with a median deviation between 0.03∘ and 0.11∘ for the right ascension and 0.02∘ and 0.07∘ for the declination. The estimated uncertainties for the speeds had a median deviation between 0.40 and 0.45 km s−1. The brightness of synthetic meteors was estimated to within +0.01 m. We have applied the software package to 177 real meteors acquired by the SPOSH camera. The median propagated uncertainties in geocentric right ascension and declination were found to be of 0.64∘ and 0.29∘, while the median propagated error in geocentric speed was 1.21 km s−1.

Evaluation of Pharmacokinetic-Based Dose Predictions of High Dose Melphalan in Patients with Myeloma

Introduction and aims: High-dose melphalan (HDM) is the commonest conditioning regimen used in autologous transplantation for multiple myeloma (MM), with >10,000 transplants performed annually. The standard dosing algorithm of 200mg/m2, with reduction to 140mg/m2 for renal impairment, has been based upon empiric dose selection, rather than pharmacokinetic (PK) and pharmacodynamic (PD) studies. We have previously examined PK and clinical outcome in 114 patients receiving HDM and shown that exposure (area under the concentration versus time curve: AUC) above the median (12.8 mg/L.h) was associated with increases in ≥ grade 3 mucositis (HR 1.2, p< 0.005), and a median overall survival of 8.5 years vs. 5.4 years for AUC below the median (HR 0.40, p < 0.001) [1]. The aims of this pilot study were to (1) test the feasibility of real-time PK in patients with MM and (2) evaluate whether a test dose reliably predicted exposure to a full dose. Methods: Thirty three patients (age range: 35 to 71 years) scheduled to receive HDM followed by ASCT were recruited from six Australian hospitals situated within 16-860km from the PK laboratory. A test dose (20 mg/m2) was administered one to three days prior to the remaining 180 mg/m2, n=29, or another dose (n = 4, 186- 200mg/m2) chosen by the treating physician. Melphalan infusion duration ranged from 9 to 36 min for the test dose and from 15 to 45 min for the remaining dose. Blood samples were collected after both doses at: 5 min, 15 min, 30 min, 40 min, 1.25 h and 2.5 h after completion of the infusion, stored immediately on ice and centrifuged within 40 minutes at 3000 rpm for 10 minutes at 4o C to collect plasma, then stored at -40°C until transported on dry ice. Melphalan concentrations were determined by HPLC with UV detection. Test dose AUC was calculated using the trapezoidal rule (Kinetica software) and used to predict what the AUC would be for the 180mg/m2 (or modified) dose, assuming linear PK. Percent deviation of actual-from-predicted AUC was calculated as % deviation = (actual AUC - predicted AUC) / predicted AUC*100. Comparison of % deviation between the first patient recruited at each institution and the remaining patients was performed using the Mann-Whitney test. Results: The predicted and actual melphalan AUC values for all 33 patients are charted (Figure 1). AUC values following the test dose were median (range): 1.34 (0.83-1.88 mg/L.h). Predicted AUC values (adjusted for subsequent dose) were median (range): 11.8 (8.3-15.8) mg/L.h, whilst actual values were 10.5 (6.3-16.0) mg/L.h. Median % deviation of actual from predicted values was -8%, (range -43 to 11%), with predictions for 23 patients (70%), being within ± 15%. The median % deviation for the first patient in each centre was -22.1%, and for subsequent patients was -7%, (p=0.046), for whom 21/27 (78%) had full dose AUC values within ± 15%. Conclusions: Test-dose PK predictions of melphalan exposure were accurate to within ± 15% for 70% of patients in this pilot study. The significantly improved AUC predictions with subsequent dosing suggest that meticulous care is required in dose administration and blood sampling. Other factors such as duration of infusion, concomitant medications and renal function are being examined in a larger cohort to identify any impact on melphalan exposure and subsequently whether PK directed dosing of HDM to achieve a desirable AUC is sufficiently reliable to implement for patients undergoing ASCT. [1] Shaw PJ et al. Biol Blood Marrow Transplant (2012): 18 (2), S207 Abs13. Figure 1. Figure 1. Disclosures Grigg: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees.