INTRODUCTIONEstimation of reflector depth and seismic velocity from seismic reflection data can be formulated as a general inverse problem. The method used to solve this problem is similar to tomographic techniques in medical diagnosis and we refer to it as seismic reflection tomography.Seismic tomography is formulated as an iterative Gauss-Newton algorithm that produces a velocitydepth model which minimizes the difference between traveltimes generated by tracing rays through the model and traveltimes measured from the data. The input to the process consists of traveltimes measured from selected events on unstacked seismic data and a first-guess velocity-depth model. Usually this first-guess model has velocities which are laterally constant and is usually based on nearby well information and/or an analysis of the stacked section. The final model generated by the tomographic method yields traveltimes from ray tracing which differ from the measured values in recorded data by approximately 5 ms root-mean-square.The indeterminancy of the inversion and the associated non uniqueness of the output model are both analyzed theoretically and tested numerically. It is found that certain aspects of the velocity field are poorly determined or undetermined.This technique is applied to an example using real data where the presence of permafrost causes a nearsurface lateral change in velocity. The permafrost is successfully imaged in the model output from tomography. In addition, depth estimates at the intersection of two lines differ by a significantly smaller amount than the corresponding estimates derived from conventional processing.Estimation of velocity and depth is often an important step in prospect evaluation in areas where lithology and structure undergo significant lateral change. Depth estimation is usually accomplished by converting zero-offset traveltimes, interpreted from a stacked section, to depth using a velocity field obtained from a normal-movement (NMO) analysis. In areas with complex lateral changes, a depth migration technique may be necessary to obtain the correct depth estimate (Lamer et aI., 1981). Both of these methods require an accurate representation of the root-mean-square (rms) velocity field. However, the stacking velocities used for such analyses can deviate significantly from rms velocities because analysis of stacking velocities assumes that the medium is laterally invariant and that traveltime trajectories for reflection events in CDP gathers are hyperbolic.Media vary laterally due to either reflector dip or curvature, or due to lateral velocity variations, or both. A large portion of the effect of reflector dip or curvature on the stacking velocity can be removed approximately by first migrating commonoffset panels with a first-guess velocity function, and then recalculating the stacking velocity in the migrated common-depthpoint (CDP) gathers (Doherty and Claerbout, 1976). The influence of lateral variations in velocity on the stacking velocity cannot be corrected this way. For lateral vari...

Summary Myeloma is one of the most common malignancies that results in osteolytic lesions of the spine. Complications, including pathological fractures of the vertebrae and spinal cord compression, may cause severe pain, deformity and neurological sequelae. They may also have significant consequences for quality of life and prognosis for patients. For patients with known or newly diagnosed myeloma presenting with persistent back or radicular pain/weakness, early diagnosis of spinal myeloma disease is therefore essential to treat and prevent further deterioration. Magnetic resonance imaging is the initial imaging modality of choice for the evaluation of spinal disease. Treatment of the underlying malignancy with systemic chemotherapy together with supportive bisphosphonate treatment reduces further vertebral damage. Additional interventions such as cement augmentation, radiotherapy, or surgery are often necessary to prevent, treat and control spinal complications. However, optimal management is dependent on the individual nature of the spinal involvement and requires careful assessment and appropriate intervention throughout. This article reviews the treatment and management options for spinal myeloma disease and highlights the value of defined pathways to enable the proper management of patients affected by it.

A B S T R A C T The cardiovascular responses elicited by dobutamine are distinctly different from those produced by other adrenergic or dopaminergic agonists. To test the hypothesis that dobutamine could have differential affinities for adrenergic receptor subtypes, and that such subtype selectivity could be related to its relatively unique pharmacologic properties, we assessed the ability of dobutamine to displace adrenergic radioligands from membrane receptors in a number of tissues of previously characterized adrenergic receptor subtype. For beta adrenergic receptors identified by (-) [3H]dihydroalprenolol (DHA), dobutamine had significantly greater affinity for the ,f3 subtype (KD = 2.5 MM in rat heart and 2.6 MM in turkey erythrocyte) than for the (82 subtype (KD = 14.8 AM in frog heart and 25.4 ,uM in rat lung) (P < 0.001). For alpha adrenergic receptors, dobutamine had markedly greater affinity for the a,-subtype identified by [3H]prazosin (KD = 0.09 ,uM in rat heart and 0.14 AM in rabbit uterus) than for the a2-subtype identified by [3H]dihydroergocryptine (DHE) (KD = 9.3 MuM in human platelet) or by [3H]-yohimbine (KD = 5.7 MM in rabbit uterus) (P < 0.001).Like other 3B,-agonists, in the absence of guanine nucleotide, dobutamine competition curves for DHA binding in rat heart demonstrated two classes of binding sites, with one site of significantly higher affinity (KD = 0.5 MM, P = 0.008) than the single class of binding sites (KD = 5.2 MuM) identified in the presence of guanine nucleotide. However, unlike /32-or a2-agonists, dobutamine displacement of DHA binding in rat lung or of DHE binding in human platelets demonstrated only a single class of binding sites, and guanine nucleotide had only minimal effects.

Aims Vertebral body tethering (VBT) is a non-fusion technique to correct scoliosis. It allows correction of scoliosis through growth modulation (GM) by tethering the convex side to allow concave unrestricted growth similar to the hemiepiphysiodesis concept. The other modality is anterior scoliosis correction (ASC) where the tether is able to perform most of the correction immediately where limited growth is expected. Methods We conducted a retrospective analysis of clinical and radiological data of 20 patients aged between 9 and 17 years old, (with a 19 female: 1 male ratio) between January 2014 to December 2016 with a mean five-year follow-up (4 to 7). Results There were ten patients in each group with a total of 23 curves operated on. VBT-GM mean age was 12.5 years (9 to 14) with a mean Risser classification of 0.63 (0 to 2) and VBT-ASC was 14.9 years (13 to 17) with a mean Risser classification of 3.66 (3 to 5). Mean preoperative VBT-GM Cobb was 47.4° (40° to 58°) with a Fulcrum unbend of 17.4 (1° to 41°), compared to VBT-ASC 56.5° (40° to 79°) with 30.6 (2° to 69°)unbend. Postoperative VBT-GM was 20.3° and VBT-ASC Cobb angle was 11.2°. The early postoperative correction rate was 54.3% versus 81% whereas Fulcrum Bending Correction Index (FBCI) was 93.1% vs 146.6%. The last Cobb angle on radiograph at mean five years’ follow-up was 19.4° (VBT-GM) and 16.5° (VBT-ASC). Patients with open triradiate cartilage (TRC) had three over-corrections. Overall, 5% of patients required fusion. This one patient alone had a over-correction, a second-stage tether release, and final conversion to fusion. Conclusion We show a high success rate (95%) in helping children avoid fusion at five years post-surgery. VBT is a safe technique for correction of scoliosis in the skeletally immature patient. This is the first report at five years that shows two methods of VBT can be employed depending on the skeletal maturity of the patient: GM and ASC. Cite this article: Bone Jt Open 2022;3(2):123–129.