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1.
Br J Anaesth ; 129(1): 13-21, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35595549

RESUMEN

BACKGROUND: Whilst intraoperative hypotension is associated with postoperative acute kidney injury (AKI), the link between intraoperative hypotension and acute kidney disease (AKD), defined as continuing renal dysfunction for up to 3 months after exposure, has not yet been studied. METHODS: We conducted a retrospective multicentre cohort study using data from noncardiac, non-obstetric surgery extracted from a US electronic health records database. Primary outcome was the association between intraoperative hypotension, at three MAP thresholds (≤75, ≤65, and ≤55 mm Hg), and the following two AKD subtypes: (i) persistent (initial AKI incidence within 7 days of surgery, with continuation between 8 and 90 days post-surgery) and (ii) delayed (renal impairment without AKI within 7 days, with AKI occurring between 8 and 90 days post-surgery). Secondary outcomes included healthcare resource utilisation for patients with either AKD subtype or no AKD. RESULTS: A total of 112 912 surgeries qualified for the study. We observed a rate of 2.2% for delayed AKD and 0.6% for persistent AKD. Intraoperative hypotension was significantly associated with persistent AKD at MAP ≤55 mm Hg (hazard ratio 1.1; 95% confidence interval: 1.38-1.22; P<0.004). However, IOH was not significantly associated with delayed AKD across any of the MAP thresholds. Patients with delayed or persistent AKD had higher healthcare resource utilisation across both hospital and intensive care admissions, compared with patients with no AKD. CONCLUSIONS: Intraoperative hypotension is associated with persistent but not delayed acute kidney disease. Both types of acute kidney disease appear to be associated with increased healthcare utilisation. Correction of intraoperative hypotension is a potential opportunity to decrease postoperative kidney injury and associated costs.


Asunto(s)
Lesión Renal Aguda , Hipotensión , Enfermedad Aguda , Lesión Renal Aguda/epidemiología , Lesión Renal Aguda/etiología , Estudios de Cohortes , Humanos , Hipotensión/epidemiología , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos
2.
Br J Anaesth ; 126(3): 720-729, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33317803

RESUMEN

BACKGROUND: Postoperative complications increase hospital length of stay and patient mortality. Optimal perioperative fluid management should decrease patient complications. This study examined associations between fluid volume and noncardiac surgery patient outcomes within a large multicentre US surgical cohort. METHODS: Adults undergoing noncardiac procedures from January 1, 2012 to December 31, 2017, with a postoperative length of stay ≥24 h, were extracted from a large US electronic health record database. Patients were segmented into quintiles based on recorded perioperative fluid volumes with Quintile 3 (Q3) serving as the reference. The primary outcome was defined as a composite of any complications during the surgical admission and a postoperative length of stay ≥7 days. Secondary outcomes included in-hospital mortality, respiratory complications, and acute kidney injury. RESULTS: A total of 35 736 patients met the study criteria. There was a U-shaped pattern with highest (Q5) and lowest (Q1) quintiles of fluid volumes having increased odds of complications and a postoperative length of stay ≥7 days (Q5: odds ratio [OR] 1.51 [95% confidence interval {CI}: 1.30-1.74], P<0.001; Q1: OR 1.20 [95% CI: 1.04-1.38], P=0.011) compared with Q3. Patients in Q5 had greater odds of more severe acute kidney injury compared with Q3 (OR 1.52 [95% CI: 1.22-1.90]; P<0.001) and respiratory complications (OR 1.44 [95% CI: 1.17-1.77]; P<0.001). CONCLUSIONS: Both very high and very low perioperative fluid volumes were associated with an increase in complications after noncardiac surgery.


Asunto(s)
Procedimientos Quirúrgicos Electivos , Fluidoterapia/efectos adversos , Atención Perioperativa/métodos , Complicaciones Posoperatorias/etiología , Estudios de Cohortes , Registros Electrónicos de Salud , Femenino , Mortalidad Hospitalaria , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/mortalidad , Estudios Retrospectivos
3.
Med J Armed Forces India ; 76(1): 77-83, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32020973

RESUMEN

BACKGROUND: Pulmonary and pleural involvement is fairly common in patients with lymphoma, especially in the setting of progressive or recurrent disease. Pleuropulmonary involvement in lymphoma may occur as a single pattern or as a combination of multiple patterns which can often mimic unrelated pathologies. METHODS: Review of our institutional database from 01 Jan 2015 to 04 Oct 2017 revealed 90 patients with pulmonary and/or pleural lesions attributable to lymphoma. These lesions were classified into various categories, and the pattern of involvement was evaluated. RESULTS: Pulmonary involvement was seen in 17.6% of patients with Hodgkin lymphoma (HL) and in 10.5% of patients with non-Hodgkin lymphoma (NHL), whereas pleural involvement was seen in 6.5% of patients with NHL. Almost all the patients in our study had findings belonging to multiple categories. Pulmonary involvement in patients with HL was seen in the form of nodules (51.6%), masses (51.6%), and direct extension from a mediastinal/hilar mass (45.2%). Patients with NHL had pulmonary involvement in the form of nodules (42.4%), direct extension from a mediastinal/hilar mass (25.4%), pulmonary masses (18.6%), and interstitial pattern (2.4%). Pleural thickening (61.5%), masses (30.8%), and effusion (15.4%) were the three patterns of pleural involvement. CONCLUSION: Nodules and masses were the two commonest patterns of pulmonary involvement in patients with HL, whereas nodules were the commonest pattern noted in patients with NHL. Pulmonary masses were seen more commonly in patients with HL than in those with NHL. Pleural involvement was seen exclusively in patients with NHL.

4.
Ann Neurol ; 83(5): 958-969, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29659050

RESUMEN

OBJECTIVE: Delayed cerebral ischemia (DCI) is a common, disabling complication of subarachnoid hemorrhage (SAH). Preventing DCI is a key focus of neurocritical care, but interventions carry risk and cannot be applied indiscriminately. Although retrospective studies have identified continuous electroencephalographic (cEEG) measures associated with DCI, no study has characterized the accuracy of cEEG with sufficient rigor to justify using it to triage patients to interventions or clinical trials. We therefore prospectively assessed the accuracy of cEEG for predicting DCI, following the Standards for Reporting Diagnostic Accuracy Studies. METHODS: We prospectively performed cEEG in nontraumatic, high-grade SAH patients at a single institution. The index test consisted of clinical neurophysiologists prospectively reporting prespecified EEG alarms: (1) decreasing relative alpha variability, (2) decreasing alpha-delta ratio, (3) worsening focal slowing, or (4) late appearing epileptiform abnormalities. The diagnostic reference standard was DCI determined by blinded, adjudicated review. Primary outcome measures were sensitivity and specificity of cEEG for subsequent DCI, determined by multistate survival analysis, adjusted for baseline risk. RESULTS: One hundred three of 227 consecutive patients were eligible and underwent cEEG monitoring (7.7-day mean duration). EEG alarms occurred in 96.2% of patients with and 19.6% without subsequent DCI (1.9-day median latency, interquartile range = 0.9-4.1). Among alarm subtypes, late onset epileptiform abnormalities had the highest predictive value. Prespecified EEG findings predicted DCI among patients with low (91% sensitivity, 83% specificity) and high (95% sensitivity, 77% specificity) baseline risk. INTERPRETATION: cEEG accurately predicts DCI following SAH and may help target therapies to patients at highest risk of secondary brain injury. Ann Neurol 2018;83:958-969.


Asunto(s)
Isquemia Encefálica/fisiopatología , Infarto Cerebral/complicaciones , Electroencefalografía , Hemorragia Subaracnoidea/fisiopatología , Adulto , Anciano , Infarto Cerebral/fisiopatología , Electroencefalografía/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Monitoreo Fisiológico/métodos , Estudios Prospectivos , Estudios Retrospectivos , Sensibilidad y Especificidad , Hemorragia Subaracnoidea/diagnóstico
5.
Neurocrit Care ; 28(2): 184-193, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-28983801

RESUMEN

BACKGROUD: Using electronic health data, we sought to identify clinical and physiological parameters that in combination predict neurologic outcomes after aneurysmal subarachnoid hemorrhage (aSAH). METHODS: We conducted a single-center retrospective cohort study of patients admitted with aSAH between 2011 and 2016. A set of 473 predictor variables was evaluated. Our outcome measure was discharge Glasgow Outcome Scale (GOS). For laboratory and physiological data, we computed the minimum, maximum, median, and variance for the first three admission days. We created a penalized logistic regression model to determine predictors of outcome and a multivariate multilevel prediction model to predict poor (GOS 1-2), intermediate (GOS 3), or good (GOS 4-5) outcomes. RESULTS: One hundred and fifty-three patients met inclusion criteria; most were discharged with a GOS of 3. Multivariate analysis predictors of mortality (AUC 0.9198) included APACHE II score, Glasgow Come Scale (GCS), white blood cell (WBC) count, mean arterial pressure, variance of serum glucose, intracranial pressure (ICP), and serum sodium. Predictors of death/dependence versus independence (GOS 4-5)(AUC 0.9456) were levetiracetam, mechanical ventilation, WBC count, heart rate, ICP variance, GCS, APACHE II, and epileptiform discharges. The multiclass prediction model selected GCS, admission APACHE II, periodic discharges, lacosamide, and rebleeding as significant predictors; model performance exceeded 80% accuracy in predicting poor or good outcome and exceeded 70% accuracy for predicting intermediate outcome. CONCLUSIONS: Variance in early physiologic data can impact patient outcomes and may serve as targets for early goal-directed therapy. Electronically retrievable features such as ICP, glucose levels, and electroencephalography patterns should be considered in disease severity and risk stratification scores.


Asunto(s)
Registros Electrónicos de Salud , Escala de Consecuencias de Glasgow , Evaluación de Resultado en la Atención de Salud/métodos , Hemorragia Subaracnoidea/diagnóstico , Adulto , Anciano , Electroencefalografía , Femenino , Humanos , Aneurisma Intracraneal/complicaciones , Aprendizaje Automático , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Alta del Paciente , Pronóstico , Estudios Retrospectivos , Hemorragia Subaracnoidea/etiología , Hemorragia Subaracnoidea/terapia
6.
J Clin Anesth ; 75: 110516, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34536719

RESUMEN

STUDY OBJECTIVE: Determine if perioperative hypotension, a modifiable risk factor, is associated with increased postoperative healthcare resource utilization (HRU). DESIGN: Retrospective cohort study. SETTING: Multicenter using the Optum® electronic health record database. PATIENTS: Patients discharged to the ward after non-cardiac, non-obstetric surgeries between January 1, 2008 and December 31, 2017 with six months of data, before and after the surgical visit. INTERVENTIONS/EXPOSURE: Perioperative hypotension, a binary variable (presence/absence) at an absolute MAP of ≤65-mmHg, measured during surgery and within 48-h after, to dichotomize patients with greater versus lesser hypotensive exposures. MEASUREMENTS: Short-term HRU defined by postoperative length-of-stay (LOS), discharge to a care facility, and 30-day readmission following surgery discharge. Mid-term HRU (within 6 months post-discharge) quantified via number of outpatient and emergency department (ED) visits, and readmission LOS. MAIN RESULTS: 42,800 distinct patients met study criteria and 37.5% experienced perioperative hypotension. After adjusting for study covariates including patient demographics and comorbidities, patients with perioperative hypotension had: longer LOS (4.01 vs. 3.83 days; LOS ratio, 1.05; 95% CI, 1.04-1.06), higher odds of discharge to a care facility (OR, 1.18; 95% CI, 1.12-1.24; observed rate 22.1% vs. 18.1%) and of 30-day readmission (OR, 1.22; 95% CI, 1.11-1.33; observed rate 6.2% vs. 5.0%) as compared to the non-hypotensive population (all outcomes, p < 0.001). During 6-month follow-up, patients with perioperative hypotension showed significantly greater HRU regarding number of ED visits (0.34 vs. 0.31 visits; visit ratio, 1.10; 95% CI, 1.05-1.15) and readmission LOS (1.06 vs. 0.92 days; LOS ratio, 1.15; 95% CI, 1.07-1.24) but not outpatient visits (10.47 vs. 10.82; visit ratio, 0.97; 95% CI, 0.95-0.99) compared to those without hypotension. There was no difference in HRU during the 6-month period before qualifying surgery. CONCLUSIONS: We report a significant association of perioperative hypotension with an increase in HRU, including additional LOS and readmissions, both important contributors to overall medical costs.


Asunto(s)
Cuidados Posteriores , Hipotensión , Humanos , Hipotensión/epidemiología , Hipotensión/etiología , Tiempo de Internación , Aceptación de la Atención de Salud , Alta del Paciente , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos
7.
Clinicoecon Outcomes Res ; 13: 109-119, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33574686

RESUMEN

OBJECTIVE: A monitoring pulmonary artery catheter (PAC) is utilized in approximately 34% of the US cardiac surgical procedures. Increased use of PAC has been reported to have an association with complication rates: significant decreases in new-onset heart failure (HF) and respiratory failure (RF), but increases in bacteremia and urinary tract infections. We assessed the impact of increasing PAC adoption on hospital costs among cardiac surgery patients for US-based healthcare systems. METHODS: An Excel-based economic model calculated annualized savings for a US hospital with various cardiac surgical volumes and PAC adoption rates. A second model, for an integrated payer-provider health system, analyzed outcomes/costs resulting from the cardiac surgical admission and for the treatment of persistent HF and RF complications in the year following surgery. Model inputs were extracted from published literature, and one-way and probabilistic sensitivity analyses were performed. RESULTS: For an acute care hospital with 500 procedures/year and 34% PAC adoption, annualized savings equalled $61,806 vs no PAC utilization. An increase in PAC adoption rate led to increased savings of $134,751 for 75% and $170,685 for 95% adoption. Savings ranged from $12,361 to $185,418 at volumes of 100 and 1500 procedures/year, respectively. For an integrated payer-provider health system with the base-case scenario of 3845 procedures/year and 34% PAC adoption, estimated savings were $596,637 for the combined surgical index admission and treatment for related complications over the following year. CONCLUSION: PAC utilization in adult cardiac surgery patients results in reduced costs for both acute care hospitals and payer-provider integrated health systems.

9.
PLoS One ; 14(12): e0226750, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31856265

RESUMEN

PURPOSE: This study examined postoperative heart failure (HF) and respiratory failure (RF) complications and related healthcare utilization for one year following cardiac surgery. METHODS: This study identified adult patients undergoing isolated coronary artery bypass graft (CABG) and/or valve procedures from the Cerner Health Facts® database. It included patients experiencing postoperative HF or RF complications. We quantified healthcare utilization using the frequency of inpatient admissions, emergency department (ED) visits with or without hospital admission, and outpatient visits. We then determined direct hospital costs from the determined healthcare utilization. We analyzed trends over time for both HF and RF and evaluated the association between surgery type and HF complication. RESULTS: Of 10,298 patients with HF complications, 1,714 patients (16.6%) developed persistent HF; of the 10,385 RF patients, 175 (1.7%) developed persistent RF. Healthcare utilization for those with persistent complications over the one-year period following index hospital discharge comprised an average number of the following visit types: Inpatient (1.49 HF; 1.55 RF), Outpatient (2.02, 0.51), ED without hospital admission (0.33, 0.13), ED + Inpatient (0.08, 0.06). Per patient annual costs related to persistent complications of HF and RF were $20,857 and $30,745, respectively. There was a significant association between cardiac surgical type and the incidence of HF, with risk for isolated valve procedures (adjusted OR 2.60; 95% CI: 2.35-2.88) and CABG + valve procedures (adjusted OR 2.38; 95% CI: 2.17-2.61) exceeding risk for isolated CABG procedures. CONCLUSIONS: This study demonstrates that HF and RF complication rates post cardiac surgery are substantial, and complication-related healthcare utilization over the first year following surgery results in significant incremental costs. Given the need for both payers and providers to focus on healthcare cost reduction, this study fills an important gap in quantifying the mid-term economic impact of postoperative cardiac surgical complications.


Asunto(s)
Procedimientos Quirúrgicos Cardíacos/efectos adversos , Costos y Análisis de Costo , Insuficiencia Cardíaca/epidemiología , Complicaciones Posoperatorias/epidemiología , Utilización de Procedimientos y Técnicas/estadística & datos numéricos , Insuficiencia Respiratoria/epidemiología , Adolescente , Adulto , Anciano , Procedimientos Quirúrgicos Cardíacos/economía , Procedimientos Quirúrgicos Cardíacos/estadística & datos numéricos , Femenino , Insuficiencia Cardíaca/economía , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/economía , Utilización de Procedimientos y Técnicas/economía , Insuficiencia Respiratoria/economía , Estados Unidos
10.
Radiat Oncol J ; 36(4): 341-347, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30518169

RESUMEN

Surgical excision along with use of postoperative radiotherapy forms an integral management of sinonasal teratocarcinosarcoma (SNTCS). However, given the rarity of the tumor, no standardised guidelines, dose, technique and target delineation exist especially in the era of modern radiation delivery techniques. This is a case of 55-year-old male diagnosed as SNTCS treated with radical ethmoidectomy followed by volumetric modulated radiotherapy, showing good local control and acceptable toxicity profile.

11.
Neurophotonics ; 5(4): 045005, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30450363

RESUMEN

Monitoring of cerebral blood flow (CBF) and autoregulation are essential components of neurocritical care, but continuous noninvasive methods for CBF monitoring are lacking. Diffuse correlation spectroscopy (DCS) is a noninvasive diffuse optical modality that measures a CBF index ( CBF i ) in the cortex microvasculature by monitoring the rapid fluctuations of near-infrared light diffusing through moving red blood cells. We tested the feasibility of monitoring CBF i with DCS in at-risk patients in the Neurosciences Intensive Care Unit. DCS data were acquired continuously for up to 20 h in six patients with aneurysmal subarachnoid hemorrhage, as permitted by clinical care. Mean arterial blood pressure was recorded synchronously, allowing us to derive autoregulation curves and to compute an autoregulation index. The autoregulation curves suggest disrupted cerebral autoregulation in most patients, with the severity of disruption and the limits of preserved autoregulation varying between subjects. Our findings suggest the potential of the DCS modality for noninvasive, long-term monitoring of cerebral perfusion, and autoregulation.

12.
Clin Neurophysiol ; 129(11): 2219-2227, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30212805

RESUMEN

OBJECTIVE: To quantify the burden of epileptiform abnormalities (EAs) including seizures, periodic and rhythmic activity, and sporadic discharges in patients with aneurysmal subarachnoid hemorrhage (aSAH), and assess the effect of EA burden and treatment on outcomes. METHODS: Retrospective analysis of 136 high-grade aSAH patients. EAs were defined using the American Clinical Neurophysiology Society nomenclature. Burden was defined as prevalence of <1%, 1-9%, 10-49%, 50-89%, and >90% for each 18-24 hour epoch. Our outcome measure was 3-month Glasgow Outcome Score. RESULTS: 47.8% patients had EAs. After adjusting for clinical covariates EA burden on first day of recording and maximum daily burden were associated with worse outcomes. Patients with higher EA burden were more likely to be treated with anti-epileptic drugs (AEDs) beyond the standard prophylactic protocol. There was no difference in outcomes between patients continued on AEDs beyond standard prophylaxis compared to those who were not. CONCLUSIONS: Higher burden of EAs in aSAH independently predicts worse outcome. Although nearly half of these patients received treatment, our data suggest current AED management practices may not influence outcome. SIGNIFICANCE: EA burden predicts worse outcomes and may serve as a target for prospective interventional controlled studies to directly assess the impact of AEDs, and create evidence-based treatment protocols.


Asunto(s)
Convulsiones/diagnóstico , Hemorragia Subaracnoidea/diagnóstico , Anciano , Anticonvulsivantes/efectos adversos , Anticonvulsivantes/uso terapéutico , Electroencefalografía , Femenino , Escala de Consecuencias de Glasgow , Humanos , Masculino , Persona de Mediana Edad , Convulsiones/tratamiento farmacológico , Convulsiones/etiología , Hemorragia Subaracnoidea/complicaciones , Hemorragia Subaracnoidea/epidemiología
13.
J Clin Neurophysiol ; 33(3): 217-26, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27258445

RESUMEN

Delayed cerebral ischemia (DCI) is the most common and disabling complication among patients admitted to the hospital for subarachnoid hemorrhage (SAH). Clinical and radiographic methods often fail to detect DCI early enough to avert irreversible injury. We assessed the clinical feasibility of implementing a continuous EEG (cEEG) ischemia monitoring service for early DCI detection as part of an institutional guideline. An institutional neuromonitoring guideline was designed by an interdisciplinary team of neurocritical care, clinical neurophysiology, and neurosurgery physicians and nursing staff and cEEG technologists. The interdisciplinary team focused on (1) selection criteria of high-risk patients, (2) minimization of safety concerns related to prolonged monitoring, (3) technical selection of quantitative and qualitative neurophysiologic parameters based on expert consensus and review of the literature, (4) a structured interpretation and reporting methodology, prompting direct patient evaluation and iterative neurocritical care, and (5) a two-layered quality assurance process including structured clinician interviews assessing events of neurologic worsening and an adjudicated consensus review of neuroimaging and medical records. The resulting guideline's clinical feasibility was then prospectively evaluated. The institutional SAH monitoring guideline used transcranial Doppler ultrasound and cEEG monitoring for vasospasm and ischemia monitoring in patients with either Fisher group 3 or Hunt-Hess grade IV or V SAH. Safety criteria focused on prevention of skin breakdown and agitation. Technical components included monitoring of transcranial Doppler ultrasound velocities and cEEG features, including quantitative alpha:delta ratio and percent alpha variability, qualitative evidence of new focal slowing, late-onset epileptiform activity, or overall worsening of background. Structured cEEG reports were introduced including verbal communication for findings concerning neurologic decline. The guideline was successfully implemented over 27 months, during which neurocritical care physicians referred 71 SAH patients for combined transcranial Doppler ultrasound and cEEG monitoring. The quality assurance process determined a DCI rate of 48% among the monitored population, more than 90% of which occurred during the duration of cEEG monitoring (mean 6.9 days) beginning 2.7 days after symptom onset. An institutional guideline implementing cEEG for SAH ischemia monitoring and reporting is feasible to implement and efficiently identify patients at high baseline risk of DCI during the period of monitoring.


Asunto(s)
Isquemia Encefálica/diagnóstico , Electroencefalografía/métodos , Monitorización Neurofisiológica/métodos , Guías de Práctica Clínica como Asunto , Garantía de la Calidad de Atención de Salud/métodos , Isquemia Encefálica/epidemiología , Humanos
14.
Med Phys ; 41(5): 051901, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24784380

RESUMEN

PURPOSE: To evaluate a three-equation three-unknown dual-energy quantitative CT (DEQCT) technique for determining region specific variations in bone spongiosa composition for improved red marrow dose estimation in radionuclide therapy. METHODS: The DEQCT method was applied to 80/140 kVp images of patient-simulating lumbar sectional body phantoms of three sizes (small, medium, and large). External calibration rods of bone, red marrow, and fat-simulating materials were placed beneath the body phantoms. Similar internal calibration inserts were placed at vertebral locations within the body phantoms. Six test inserts of known volume fractions of bone, fat, and red marrow were also scanned. External-to-internal calibration correction factors were derived. The effects of body phantom size, radiation dose, spongiosa region segmentation granularity [single (∼17 × 17 mm) region of interest (ROI), 2 × 2, and 3 × 3 segmentation of that single ROI], and calibration method on the accuracy of the calculated volume fractions of red marrow (cellularity) and trabecular bone were evaluated. RESULTS: For standard low dose DEQCT x-ray technique factors and the internal calibration method, the RMS errors of the estimated volume fractions of red marrow of the test inserts were 1.2-1.3 times greater in the medium body than in the small body phantom and 1.3-1.5 times greater in the large body than in the small body phantom. RMS errors of the calculated volume fractions of red marrow within 2 × 2 segmented subregions of the ROIs were 1.6-1.9 times greater than for no segmentation, and RMS errors for 3 × 3 segmented subregions were 2.3-2.7 times greater than those for no segmentation. Increasing the dose by a factor of 2 reduced the RMS errors of all constituent volume fractions by an average factor of 1.40 ± 0.29 for all segmentation schemes and body phantom sizes; increasing the dose by a factor of 4 reduced those RMS errors by an average factor of 1.71 ± 0.25. Results for external calibrations exhibited much larger RMS errors than size matched internal calibration. Use of an average body size external-to-internal calibration correction factor reduced the errors to closer to those for internal calibration. RMS errors of less than 30% or about 0.01 for the bone and 0.1 for the red marrow volume fractions would likely be satisfactory for human studies. Such accuracies were achieved for 3 × 3 segmentation of 5 mm slice images for: (a) internal calibration with 4 times dose for all size body phantoms, (b) internal calibration with 2 times dose for the small and medium size body phantoms, and (c) corrected external calibration with 4 times dose and all size body phantoms. CONCLUSIONS: Phantom studies are promising and demonstrate the potential to use dual energy quantitative CT to estimate the spatial distributions of red marrow and bone within the vertebral spongiosa.


Asunto(s)
Médula Ósea/efectos de la radiación , Huesos/efectos de la radiación , Radiometría/métodos , Radioterapia/métodos , Tomografía Computarizada por Rayos X/métodos , Tejido Adiposo/efectos de la radiación , Algoritmos , Tamaño Corporal/efectos de la radiación , Calibración , Humanos , Vértebras Lumbares , Modelos Biológicos , Dosis de Radiación , Asta Dorsal de la Médula Espinal/efectos de la radiación
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