Comparison of Radiologists and Other Specialists in the Performance of Lumbar Puncture Procedures Over Time.

BACKGROUND AND PURPOSE: Lumbar punctures may be performed by many different types of health care providers. We evaluated the percentages of lumbar punctures performed by radiologists-versus-nonradiologist providers, including changes with time and discrepancies between specialties. MATERIALS AND METHODS: Lumbar puncture procedure claims were identified in a 5% sample of Medicare beneficiaries from 2004 to 2017 and classified by provider specialty, site of service, day of week, and patient complexity. Compound annual growth rates for 2004 versus 2017 were calculated; t test and χ2 statistical analyses were performed. RESULTS: Lumbar puncture use increased from 163.3 to 203.4 procedures per 100,000 Medicare beneficiaries from 2004 to 2017 (overall rate, 190.3). Concurrently, the percentage of lumbar punctures performed by radiologists increased from 37.1% to 54.0%, while proportions performed by other major physician specialty groups either declined (eg, neurologists from 23.5% to 10.0%) or were largely unchanged. While radiologists saw the largest absolute increase in the percentage of procedures, the largest relative increase occurred for nonphysician providers (4.2% in 2004 to 7.5% in 2017; +78.6%). In 2017, radiologists performed most procedures on weekdays (56.2%) and a plurality on weekends (38.2%). Comorbidity was slightly higher in patients undergoing lumbar puncture by radiologists (P < .001). CONCLUSIONS: Radiologists now perform most lumbar puncture procedures for Medicare beneficiaries in both the inpatient and outpatient settings. The continuing shift in lumbar puncture responsibility from other specialists to radiologists has implications for clinical workflows, cost, radiation exposure, and postgraduate training.

Evolving Use of fMRI in Medicare Beneficiaries.

Using the Medicare Physician-Supplier Procedure Summary Master File, we evaluated the evolving use of fMRI in Medicare fee-for-service beneficiaries from 2007 through 2017. Annual use rates (per 1,000,000 enrollees) increased from 17.7 to 32.8 through 2014 and have remained static since. Radiologists have remained the dominant specialty group from 2007 to 2017 (86.4% and 88.6% of all services, respectively), and the outpatient setting has remained the dominant place of service (65.4% and 65.4%, respectively).

Characteristics of MR Neuroimaging Services Billed by Radiologists versus Nonradiologists.

BACKGROUND AND PURPOSE: Although most neuroimaging examinations are interpreted by radiologists, many nonradiologists provide interpretation services. We studied day of the week, site of service, and patient complexity differences for common Medicare MR neuroimaging examinations interpreted by radiologists versus nonradiologists. MATERIALS AND METHODS: Using carrier claims files for a 5% sample of Medicare beneficiaries from 2012 to 2014, we identified all claims for brain and lumbar spine MR imaging examinations. Services were categorized by physician specialty, day of the week, and the site of service. Patient complexity was calculated using Charlson Comorbidity Indices. The χ2 was performed to test statistical significance. RESULTS: A provider specialty could be identified for 568,423 brain and lumbar spine MR imaging examinations. Of weekday examinations, radiologists interpreted 475,288 (92.3%), and nonradiologists, 39,510 (7.7%). Of weekend examinations, radiologists interpreted 52,028 (97.0%) and nonradiologists 1597 (3.0%). Radiologists interpreted 145,904 (98.7%) examinations in the inpatient hospital and emergency department settings versus 1882 (1.3%) by nonradiologists. Of all examinations, 44,547 of those interpreted by radiologists (8.4%) were on the most clinically complex patients versus 2139 (5.2%) for nonradiologists. All interspecialty differences for day of the week, the site of service, and patient complexity were statistically significant (P < .001). CONCLUSIONS: Although radiologists interpret most common MR neuroimaging examinations for Medicare beneficiaries, in contrast to nonradiologists, they disproportionately render those services on weekends, in higher acuity sites, and on more complex patients. To optimize access and minimize disparities in necessary neuroimaging, quality metrics should consider such service characteristics.

Osteocyte viability with glucocorticoid treatment: relation to histomorphometry.

BACKGROUND: Glucocorticoid induced osteoporosis is a common clinical problem. OBJECTIVE: To determine the pathophysiology of glucocorticoid induced osteoarthritis at the organ level. METHODS: Iliac crest biopsy specimens were obtained from nine patients receiving prednisone treatment for rheumatoid arthritis. Osteocyte viability and histomorphometric indices were assessed. RESULTS: Compared with controls, glucocorticoid treated subjects had reduced trabecular thickness and increased erosion. The number of viable osteocytes was significantly decreased in glucocorticoid treated patients compared with controls. CONCLUSION: The impaired bone formation, increased erosion and, importantly, loss of viable osteocytes are all likely to contribute to the increased risk of fracture in these patients.

Histological identification of osteocytes in the allegedly acellular bone of the sea breams Acanthopagrus australis, Pagrus auratus and Rhabdosargus sarba (Sparidae, Perciformes, Teleostei).

The bone of advanced teleost fishes such as those of the family Sparidae is said to lack osteocytes or to be acellular. Acellularity has been determined by apparent lack of osteocyte lacunae. This study questions the validity of this criterion. Scanning electron and light microscopy of paraffin and resin sections were used to show that the sides of sea bream mandibles consist of laminar parallel-fibred bone that we call tubular bone, because it contains tubules, and localised regions of Sharpey fibre bone. Osteocytes lie along the walls of tubules that also contain collagen fibril bundles (T-fibres), or in the lumens of tubules that do not contain T-fibres. We show that the osteocytes are derived from osteoblasts. The T-fibre system is different from other fibre systems that have been described. The tubules enclose wide T-fibres (lenticular in cross-section, maximum width about 8 microns) that taper at their ends and continue as thin T-fibres (round in cross-section, about 2 microns wide). The T-fibres originate in the periosteum. In mature tubular bone, spaces of increasing size develop around the osteocytes. Osteocytes are released from the bone matrix and become postosteocytes or bone-lining cells. Secondary bone lines the largest spaces. In Sharpey fibre bone, small osteocytes in small lacunae (about 2 microns wide) are found in columns parallel to the Sharpey fibres. Large osteocytes are found in large round spaces and are much larger than comparable osteocytes in lacunae in the bone of the salmon Salmo salar. We conclude that an absence of visible or conventional osteocyte lacunae does not mean that the cells themselves are absent. There are cells and two types of collagen fibre bundle in the tubules. The cells are osteocytes derived from osteoblasts, and these osteocytes apparently resorb bone with the result that large amounts of bone are destroyed. "Acellular" tubular and Sharpey fibre bone are types of cellular bone that differ from each other and from conventional cellular bone.

Structure and origin of the tooth pedicel (the so-called bone of attachment) and dental-ridge bone in the mandibles of the sea breams Acanthopagrus australis, Pagrus auratus and Rhabdosargus sarba (Sparidae, Perciformes, Teleostei).

Scanning electron and light microscopy were used to show that the pedicels of fish teeth (the so-called "bones of attachment") consist of three types of dentine that lie concentrically around a pulp cavity lined with typical odontoblasts with cytoplasmic processes in dentinal tubules. Circumpulpal canalar dentine forms on a thin layer of orthodentine that is encased in mantle dentine. Canalar dentine is a new name given to a dentine that is similar to vasodentine in canal arrangement, but not apparently in canal content. An inner series of wide, radial canals and an outer series of highly-branched thin canals of two diameters are inhabited by a population of cells, the osteodentocytes, and collagen fibril bundles. The flat, oval osteodentocytes appear to be quiescent cells, lying on the sides of the tubules and covered by a sheath. Plump, intensely metachromatic osteodentocytes appear to be more synthetically active. The canals and the osteodentocytes originate from blood capillaries enclosed in the predentine during dentinogenesis. New teeth begin within the small cavities present in spongy bone that were enlarged by multinucleated osteoclasts during tooth growth. Pedicel formation is initiated by the extension of the crown mantle dentine, forming the outer layer of the crimped ligament and outlining the future length and curvature of the pedicel. Central and inner ligament zones are subsequently formed as orthodentine is secreted in both crown and pedicel, and canalar dentine in the pedicel. Spongy bone osteogenesis begins during stage 1 of pedicel formation with the aggregation of osteoblasts and blood capillaries in the bone cavities and in the dermis between the pedicels. Loose fibrillar osteoid condenses into incomplete thin trabeculae bordered by intensely metachromatic osteoblasts. Osteoblasts become enclosed in the developing trabeculae that thicken to give mature spongy bone with osteocytes throughout. We conclude that the pedicels are the true bases of teeth, that the dental ridge is formed from pedicels and spongy bone, and that sea bream spongy bone is cellular. The term "bone of attachment" is inappropriate for the pedicel. It can be used for the spongy bone between the compact bone of the jaw and between adjacent pedicel.

In vivo probe of central cholinergic systems.

Age-related cognitive impairments and dementia of Alzheimer type have been linked to alterations in the cholinergic system. In the present study, evoked potentials and neuropsychological testing were obtained in healthy subjects during neuropharmacological manipulations including: scopolamine (anticholinergic), scopolamine plus physostigmine (anticholinesterase), scopolamine plus methylphenidate (adrenergic), and placebo. Scopolamine prolonged P3 latency and reduced spectral power of long latency evoked potentials without significantly altering earlier components. Physostigmine partially reversed these effects, but methylphenidate did not. Motor speed was slowed by scopolamine, but not by scopolamine plus methylphenidate. Cholinergic systems appear to be involved in generation or modulation of the P3 potential, possibly secondary to the cholinergic role in selective attention. Similar techniques may be useful as in vivo probes of central cholinergic function and thus as research and diagnostic aids in aging and disease.

Ultrastructure and chemical composition of calcite urinary calculi in Chinese swamp buffalo.

Four urinary calculi, derived from Chinese swamp buffalo, were studied by using qualitative chemical analysis, X-ray diffraction, scanning electron microscopy and qualitative energy dispersive (electron probe) microanalysis. Qualitative chemical analysis showed that the predominant ions were calcium and carbonate with small amounts of magnesium and ammonium. X-ray diffraction confirmed that the calculi were primarily composed of calcium carbonate (calcite). On ultrastructural examination, three apparently distinct structural regions were identified in the calculi: outer large laminations; cavities containing variable numbers of small spheres and rods; and large spheres. There did not appear to be material that acted as a nidus and all regions, on qualitative electron probe analysis, contained primarily calcium with trace amounts of magnesium, phosphorus, potassium and chloride. It was concluded that calcite calculi in Chinese swamp buffalo are probably formed through a process of asynchronous layering and that nidus formation may not be necessary. Moreover, the ultrastructure of the calcite calculi is similar to that reported for siliceous calculi in ruminants and this suggests that similar factors may be involved in their formation.

Prolonged local analgesia for inguinal herniorrhaphy with bupivacaine and dextran.

In a randomised double-blind trial 40 patients undergoing unilateral inguinal herniorrhaphy were each locally anaesthetised with one of a series of 8 solutions. These contained bupivacaine, both with and without adrenaline, mixed with an equal volume of dextran 40, dextran 70, dextran 110, or saline. Significant prolongation of local analgesia was achieved with high-molecular-weight dextran and this was most consistently obtained when the solution used contained adrenaline. The possible influence of the pH of the solutions used, together with the ways in which dextran may affect the duration of action of bupivacaine are discussed.