Organizational readiness and implementation fidelity of an early childhood education and care-specific physical activity policy intervention: findings from the Play Active trial.

BACKGROUND: Many children do not accumulate sufficient physical activity for good health and development at early childhood education and care (ECEC). This study examined the association between ECEC organizational readiness and implementation fidelity of an ECEC-specific physical activity policy intervention. METHODS: Play Active aimed to improve the ECEC educator's physical activity practices. We investigated the implementation of Play Active using a Type 1 hybrid study (January 2021-March 2022). Associations between organizational readiness factors and service-level implementation fidelity were examined using linear regressions. Fidelity data were collected from project records, educator surveys and website analytics. RESULTS: ECEC services with higher levels of organizational commitment and capacity at pre-implementation reported higher fidelity scores compared to services with lower organizational commitment and capacity (all Ps < 0.05). Similarly, services who perceived intervention acceptability and appropriateness at pre-implementation to be high had higher fidelity scores (P < 0.05). Perceived feasibility and organizational efficacy of Play Active were associated with higher but nonsignificant fidelity scores. CONCLUSIONS: Results indicate that organizational readiness factors may influence the implementation of ECEC-specific physical activity policy interventions. Therefore, strategies to improve organizational readiness should be developed and tested. These findings warrant confirmation in the ECEC and other settings and with other health behavior interventions.

Drivers of mortality in patients with chronic coronary disease in the low-dose colchicine 2 trial.

BACKGROUND: Low-dose colchicine significantly reduces the risk of cardiovascular events in patients with chronic coronary disease. An increase of non-cardiovascular death raised concerns about its safety. This study reports cause-specific mortality and baseline predictors of mortality in the Low-Dose Colchicine 2 (LoDoCo2) trial. METHODS: Patients with chronic coronary disease were randomly allocated to colchicine 0.5 mg once daily or placebo on a background of optimal medical therapy. Cause-specific mortality data were analysed, stratified by treatment status. Multivariate analyses were performed to examine the predictors of mortality as well as cardiovascular and non-cardiovascular death. RESULTS: After a median 28.6 months follow-up, 133 out of 5522 participants (2.4%) died. Forty-five deaths were cardiovascular (colchicine versus placebo: 20 [0.7%] versus 25 [0.9%], HR, 0.80; 95% CI, 0.44-1.44), while eighty-eight deaths were non-cardiovascular (53 [1.9%] versus 35 [1.3%]; HR, 1.51; 95% CI, 0.99-2.31). Forty-eight deaths were due to cancer (26 [0.9%] versus 22 [0.8%]), thirteen end-stage pulmonary disease (9 [0.3%] versus 4 [0.1%]), eight infection (4 [0.1%] versus 4 [0.1%]), five dementia (4 [0.1%] versus 1 [0.0%]) and five related multiple organ failure (3 [0.1%] versus 2 [0.1%]). Multivariable analysis demonstrated age > 65 years was the only independent baseline characteristic associated with non-cardiovascular death (HR, 3.65; 95% CI, 2.06-6.47). CONCLUSIONS: During the LoDoCo2 trial, assignment to colchicine was not associated with an adverse effect on any specific causes of death. Most deaths were related to non-cardiovascular causes, underscoring the importance of comorbidities as drivers of all-cause mortality in patients with chronic coronary disease.

Hospital-Acquired Infection, Length of Stay, and Readmission in Elective Surgery Patients Transfused 1 Unit of Red Blood Cells: A Retrospective Cohort Study.

BACKGROUND: Most patients transfused red blood cells in elective surgery receive small volumes of blood, which is likely to be discretionary and avoidable. We investigated the outcomes of patients who received a single unit of packed red blood cells during their hospital admission for an elective surgical procedure when compared to those not transfused. METHODS: This retrospective cohort study included elective surgical admissions to 4 hospitals in Western Australia over a 6-year period. Participants were included if they were at least 18 years of age and were admitted for elective surgery between July 2014 and June 2020. We compared outcomes of patients who had received 1 unit of red blood cells to patients who had not been transfused. To balance differences in patient characteristics, we weighted our multivariable regression models using the inverse probability of treatment. In addition to propensity score weighting, our multivariable regression models adjusted for hemoglobin level, surgical procedure, patient age, gender, comorbidities, and the transfusion of fresh-frozen plasma or platelets. Outcomes studied were hospital-acquired infection, hospital length of stay, and all-cause emergency readmissions within 28 days. RESULTS: Overall, 767 (3.2%) patients received a transfusion of 1 unit of red blood cells throughout their admission. In the propensity score weighted analysis, the transfusion of a single unit of red blood cells was associated with higher odds of hospital-acquired infection (odds ratio, 3.94; 95% confidence interval [CI], 2.99-5.20; P < .001). Patients who received 1 unit of red blood cells throughout their admission were more likely to have a longer hospital stay (rate ratio, 1.57; 95% CI, 1.51-1.63; P < .001) and had 1.42 (95% CI, 1.20-1.69; P < .001) times higher odds of 28-day readmission. CONCLUSIONS: These results suggest that avoidance of even small volumes of packed red blood cells may prevent adverse clinical outcomes. This may encourage hospital administrators to implement strategies to avoid the transfusion of even small volumes of red blood cells by applying patient blood management practices.

Developing PHarmacie-R: A bedside risk prediction tool with a medicines management focus to identify risk of hospital readmission.

BACKGROUND: The imperative to identify patients at risk of medication-related harm has never been greater. Hospital clinicians cannot easily predict risk of readmission or harm. Candidate variables associated with medication-related harm derived from the literature or significantly represented in a complex patient cohort have been previously described by PHarmacie-4. With a focus on polypharmacy and high-risk medicines in vulnerable patient cohorts, PHarmacie-4 was easy to use and highlighted risks. However it over-estimated risk, reducing its usefulness in stratifying risk of readmission. OBJECTIVE: Develop a risk prediction tool built into a smart phone app, enabling clinicians to identify and refer high-risk patients for an early post-discharge medicines review. Demonstrate usability, real world application and validity in an independent dataset. METHODS: A retrospective, observational study was conducted with 1201 randomly selected patients admitted to Sir Charles Gairdner Hospital between June 1, 2016 to December 31, 2016. Patient characteristics and outcomes of interest were reported, including unplanned hospital utilisation at 30, 60 and 90 days post-discharge. Using multivariable logistic regression modelling, an algorithm was developed, built into a smart phone app and used and validated in an independent dataset. RESULTS: 738 patients (61%) were included in the derivation sample. The best predictive performance was achieved by PHarmacie-R (C-statistic 0.72, 95% CI 0.68-0.75) which included PHarmacie-4 risk variables, a non-linear effect of age, unplanned hospital utilisation in the preceding six months and gender. The independent validation dataset had a C-statistic of 0.64 (95% CI 0.56-0.72). CONCLUSION: PHarmacie-R is the first readmission risk prediction tool, built into a smart phone app, focussing on polypharmacy and high-risk medicines in vulnerable patients. It can assist clinical pharmacists to identify medical inpatients who may benefit from early post-discharge medication management services. External validation is needed to enable application in other clinical settings.

Polygenic basis and biomedical consequences of telomere length variation.

Telomeres, the end fragments of chromosomes, play key roles in cellular proliferation and senescence. Here we characterize the genetic architecture of naturally occurring variation in leukocyte telomere length (LTL) and identify causal links between LTL and biomedical phenotypes in 472,174 well-characterized UK Biobank participants. We identified 197 independent sentinel variants associated with LTL at 138 genomic loci (108 new). Genetically determined differences in LTL were associated with multiple biological traits, ranging from height to bone marrow function, as well as several diseases spanning neoplastic, vascular and inflammatory pathologies. Finally, we estimated that, at the age of 40 years, people with an LTL >1 s.d. shorter than the population mean had a 2.5-year-lower life expectancy compared with the group with ≥1 s.d. longer LDL. Overall, we furnish new insights into the genetic regulation of LTL, reveal wide-ranging influences of LTL on physiological traits, diseases and longevity, and provide a powerful resource available to the global research community.

Relationship of pleural fluid pH and glucose: a multi-centre study of 2,971 cases.

BACKGROUND: Pleural fluid pH and glucose levels are both recommended in the workup of pleural effusions. Whether their levels correlate and predict each other or contribute independent knowledge is unclear. We aimed to investigate the pH/glucose relationship, assess their concordance and ascertain whether performing both tests provides additional information to performing either test alone. METHODS: The pH and glucose measurements from 2,971 pleural fluid samples, from three centers in Spain, UK and Australia, were categorized into Cancer (n=1,045), Infection (n=544), Tuberculosis (n=249) and Others (n=1,133) groups. The relationship between pH and glucose values and their concordance at clinically relevant cutoffs (pH 7.2 and glucose 3.3 mmol/L) were assessed. RESULTS: The mean pH of the cohort was 7.38 (SD 0.22) and median glucose 5.99 (range, 0.00-29.36) mmol/L. A regression model of the relationship between glucose (log-transformed) and pH with a restricted cubic spline showed linear (P<0.01) and nonlinear effects (P<0.01). The relationship was strong with a narrow confidence interval but the prediction interval was wide. Most (91.9%) samples were concordant using pH and glucose levels at cutoffs of 7.20 and 3.30 mmol/L respectively. Using pH alone, without glucose, captured 95.0% of the infection-related effusions with either pH or glucose below cutoff and glucose alone identified 91.7%. CONCLUSIONS: Pleural fluid pH and glucose have a strong non-linear relationship but, in most situations, the level of one cannot accurately predict the other. Concordance rates were high and either test is sufficient in the majority of cases.

Aggressive versus symptom-guided drainage of malignant pleural effusion via indwelling pleural catheters (AMPLE-2): an open-label randomised trial.

BACKGROUND: Indwelling pleural catheters are an established management option for malignant pleural effusion and have advantages over talc slurry pleurodesis. The optimal regimen of drainage after indwelling pleural catheter insertion is debated and ranges from aggressive (daily) drainage to drainage only when symptomatic. METHODS: AMPLE-2 was an open-label randomised trial involving 11 centres in Australia, New Zealand, Hong Kong, and Malaysia. Patients with symptomatic malignant pleural effusions were randomly assigned (1:1) to the aggressive (daily) or symptom-guided drainage groups for 60 days and minimised by cancer type (mesothelioma vs others), performance status (Eastern Cooperative Oncology Group [ECOG] score 0-1 vs ≥2), presence of trapped lung, and prior pleurodesis. Patients were followed up for 6 months. The primary outcome was mean daily breathlessness score, measured by use of a 100 mm visual analogue scale during the first 60 days. Secondary outcomes included rates of spontaneous pleurodesis and self-reported quality-of-life measures. Results were analysed by an intention-to-treat approach. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12615000963527. FINDINGS: Between July 20, 2015, and Jan 26, 2017, 87 patients were recruited and randomly assigned to the aggressive (n=43) or symptom-guided (n=44) drainage groups. The mean daily breathlessness scores did not differ significantly between the aggressive and symptom-guided drainage groups (geometric means 13·1 mm [95% CI 9·8-17·4] vs 17·3 mm [13·0-22·0]; ratio of geometric means 1·32 [95% CI 0·88-1·97]; p=0·18). More patients in the aggressive group developed spontaneous pleurodesis than in the symptom-guided group in the first 60 days (16 [37·2%] of 43 vs five [11·4%] of 44, p=0·0049) and at 6 months (19 [44·2%] vs seven [15·9%], p=0·004; hazard ratio 3·287 [95% CI 1·396-7·740]; p=0·0065). Patient-reported quality-of-life measures, assessed with EuroQoL-5 Dimensions-5 Levels (EQ-5D-5L), were better in the aggressive group than in the symptom-guided group (estimated means 0·713 [95% CI 0·647-0·779] vs 0·601 [0·536-0·667]). The estimated difference in means was 0·112 (95% CI 0·0198-0·204; p=0·0174). Pain scores, total days spent in hospital, and mortality did not differ significantly between groups. Serious adverse events occurred in 11 (25·6%) of 43 patients in the aggressive drainage group and in 12 (27·3%) of 44 patients in the symptom-guided drainage group, including 11 episodes of pleural infection in nine patients (five in the aggressive group and six in the symptom-guided drainage group). INTERPRETATION: We found no differences between the aggressive (daily) and the symptom-guided drainage regimens for indwelling pleural catheters in providing breathlessness control. These data indicate that daily indwelling pleural catheter drainage is more effective in promoting spontaneous pleurodesis and might improve quality of life. FUNDING: Cancer Council of Western Australia and the Sir Charles Gairdner Research Advisory Group.

The effect of asthma on the perimeter of the airway basement membrane.

When comparing the pathology of airways in individuals with and without asthma, the perimeter of the basement membrane (Pbm) is used as a marker of airway size, as it is independent of airway smooth muscle shortening or airway collapse. The extent to which the Pbm is itself altered in asthma has not been quantified. The aim of this study was to compare the Pbm from the same anatomical sites in postmortem lungs from subjects with (n = 55) and without (n = 30) asthma (nonfatal or fatal). Large and small airways were systematically sampled at equidistant "levels" from the apical segment of the left upper lobes and anterior and basal segments of the left lower lobes of lungs fixed in inflation. The length of the Pbm was estimated from cross sections of airway at each relative level. Linear mixed models were used to investigate the relationships between Pbm and sex, age, height, smoking status, airway level, and asthma group. The final model showed significant interactions between Pbm and airway level in small (<3 mm) airways, in subjects having asthma (P < 0.0001), and by sex (P < 0.0001). No significant interactions for Pbm between asthma groups were observed for larger airways (equivalent to a diameter of ∼3 mm and greater) or smoking status. Asthma is not associated with remodeling of the Pbm in large airways. In medium and small airways, the decrease in Pbm in asthma (≤20%) would not account for the published differences in wall area or area of smooth muscle observed in cases of severe asthma.

Measuring height in recumbent critical care patients.

BACKGROUND: Estimates of the height of patients in the intensive care unit are required to adhere to clinical guidelines for drug dosages, ventilatory support, and nutrition. The gold standard of standing height cannot be used because these patients are often unconscious and recumbent. The ability of physiotherapists or dietitians to measure height in unconscious, recumbent patients has not been evaluated. OBJECTIVES: To compare the accuracy of physicians, physiotherapists, and dietitians in estimating the height of recumbent critical care patients by using existing practice methods. METHODS: A total of 35 patients were recruited from the cardiothoracic preadmission clinic, where standing height is routinely measured by a physiotherapist. After surgery, in the intensive care unit, 1 physician, 2 physiotherapists, and 2 dietitians measured each recumbent patient's height. Three methods were used: observation, whole-body measurement, and height estimated by using length of the forearm and the British Association for Parenteral and Enteral Nutrition normative chart. Difference from standing height was measured from zero and was compared across professions and methods, with zero indicating no difference. RESULTS: Overall, 17 physicians, 4 dietitians, and 9 physiotherapists consented to measure patients. After adjustments for method, measurements by physiotherapists did not differ significantly from the gold standard (P = .59), whereas those of physicians (P = .02) and dietitians (P < .001) did. CONCLUSIONS: Physiotherapists' measurements of supine height of recumbent critical care patients, obtained by using a nonrigid measuring tape, are more accurate than measurements obtained by physicians and dietitians.

Predictors of clinical use of pleurodesis and/or indwelling pleural catheter therapy for malignant pleural effusion.

BACKGROUND: The clinical course of patients with malignant pleural effusions (MPEs) varies. The decision to undertake "definitive therapy" (pleurodesis, indwelling pleural catheter [IPC], or both) for MPEs is decided on a case-by-case basis. Identifying factors that predict definitive therapy may help guide early initiation of treatment. The aim of the study was to identify clinical, laboratory, and radiologic predictors associated with clinicians' prescription of definitive therapy for patients with MPE. METHODS: A multicenter, observational study was conducted over 55 months involving tertiary centers in Perth, Western Australia, Australia, and Lleida, Spain. Demographic, clinical, radiologic, biochemical, and histologic data and the treatments received were recorded. Logistic regression was performed to determine the variables useful for predicting definitive therapy. RESULTS: Data of 540 patients (365 from Perth and 184 from Lleida) were analyzed; 537 fulfilled the criteria of an MPE. Definitive therapy was used in 288 patients (53.6%): 199 received a pleurodesis and 89 an IPC. Univariate analysis of the combined cohort revealed that definitive therapy was more likely if the effusion has low pH, either as a continuous variable (OR, 30.30; P < .01) or with a pH cutoff of < 7.2 (OR, 2.09; P = .03); was large (> 50% of hemithorax) (OR, 2.75; P < .01); or was associated with mesothelioma (OR, 1.83; P < .01). Following multivariate analysis, low pleural pH (OR, 37.04; P < .01), large effusions (OR, 3.31; P < .01), and increasing age (OR 1.02, P = .01) were associated with the use of definitive therapy. CONCLUSIONS: Patients with MPE with an effusion of low pleural fluid pH and large size on radiographs at first presentation are more likely to be treated with pleurodesis and/or IPC.

Evidence-Based Self-care Guidelines for People Receiving Chemotherapy: Do They Reduce Symptom Burden and Psychological Distress?

BACKGROUND: Despite numerous evidence-based guidelines (EBGs) being developed to manage the symptom burden associated with cancer and chemotherapy, there is a paucity of research exploring their efficacy. OBJECTIVE: The aim of this study was to explore the effect of implementing EBGs to reduce the symptom burden and psychological distress of cancer patients requiring outpatient chemotherapy at an acute, tertiary care public hospital in Western Australia. METHODS: The study was conducted in 2 populations and stages, using action research to promote change. Stage 1 assessed prevalence; in stage 2, specific EBGs were implemented. Symptom prevalence, severity, and bother were determined at baseline and 1 week and 1 month after initial chemotherapy, to allow comparison between stages. RESULTS: Stage 2 participants did better at managing feeling low (odds ratio, 2.33; 95% confidence interval, 1.47-3.70; P < .001) and vomiting (odds ratio, 2.37; 95% confidence interval, 1.13-4.97; P = .022). Bother was greater in stage 2 at baseline for vomiting (P = .040), pain (P = .017), feeling tired (P = .038), feeling anxious or worried (P = .001), and feeling low (P = .024). By 1 month, only feeling anxious or worried (P = .023) and feeling low (P = .006) differed. Severity was greater in stage 2 at baseline for pain (P = .025) and feeling anxious or worried (P = .008). By 1 month, only feeling anxious or worried (P = .010) differed. CONCLUSION: Effective self-care strategies to manage the adverse effects of chemotherapy should be evidence based but individualized, as our findings suggest; for some, focusing on their symptoms may not always be beneficial. IMPLICATIONS FOR PRACTICE: Providing patients with pathways to information as needed may be preferable to administering multiple EBGs.

Merkel cell polyomavirus and p63 status in Merkel cell carcinoma by immunohistochemistry: Merkel cell polyomavirus positivity is inversely correlated with sun damage, but neither is correlated with outcome.

The aim of this study was to determine the frequency of Merkel cell polyomavirus (MPyV) and p63 positivity by immunohistochemistry in a large cohort of primary Merkel cell carcinoma (MCC) from a region with high rates of actinic damage. We also aimed to determine whether there is any relationship between these markers and histological correlates of chronic sun exposure and to identify whether these markers have prognostic significance in our population. Ninety-five cases of primary cutaneous MCC were identified and stained with immunohistochemical markers for MPyV and p63. The presence of solar elastosis and squamous dysplasia in the overlying/adjacent skin were recorded as markers of actinic damage. Follow up data were obtained from the Western Australian Cancer Registry. MPyV was detected by immunohistochemistry in 23% of cases. There was a statistically significantly lower rate of positivity in tumours associated with markers of chronic sun damage as assessed by the presence of solar elastosis and squamous dysplasia. There was no association with overall or disease specific survival. p63 positivity was detected in 17% of cases. There was no association with markers of actinic damage or with overall or disease specific survival.Our data demonstrate a significant difference in rates of immunohistochemical positivity for MPyV between MCC in sun-damaged and non-sun-damaged sites. This may go some way to explaining previously identified geographical differences. When compared with a number of studies from Europe and North America, p63 positivity is less common in our population and does not show the strong prognostic significance that has been found in these other regions.

Catheter tract metastasis associated with indwelling pleural catheters.

BACKGROUND: Indwelling pleural catheters (IPCs) are commonly used to manage malignant effusions. Tumor spread along the catheter tract remains a clinical concern for which limited data exist. We report the largest series of IPC-related catheter tract metastases (CTMs) to date, to our knowledge. METHODS: This is a single-center, retrospective review of IPCs inserted over a 44-month period. CTM was defined as a new, solid chest wall lesion over the IPC insertion site and/or the tunneled subcutaneous tract that was clinically compatible with a malignant tract metastasis. RESULTS: One hundred ten IPCs were placed in 107 patients (76.6% men; 60% with mesothelioma). CTM developed in 11 cases (10%): nine with malignant pleural mesothelioma and two with metastatic adenocarcinoma. CTM often developed late (median, 280 days; range, 56-693) post-IPC insertion. Seven cases had chest wall pain, and six received palliative radiotherapy to the CTM. Radiotherapy was well tolerated, with no major complications and causing no damage to the catheters. Longer interval after IPC insertion was the sole significant risk factor for development of CTM (OR, 2.495; 95% CI, 1.247-4.993; P = .0098) in the multivariate analyses. CONCLUSIONS: IPC-related CTM is uncommon but can complicate both mesothelioma and metastatic carcinomas. The duration of interval after IPC insertion is the key risk factor identified for development of CTM. Symptoms are generally mild and respond well to radiotherapy, which can be administered safely without removal of the catheter.

Immunophenotypic analysis of ovarian endometrioid adenocarcinoma: correlation with KRAS mutation and the presence of endometriosis.

AIMS: The relationship between endometriosis and ovarian endometrioid adenocarcinoma (OEC) is well recognised but it is unclear whether endometriosis positive and negative OECs develop via similar pathogenetic mechanisms. MATERIALS: Sixty-seven low grade OECs (35 associated with endometriosis) were stained immunohistochemically for ß-catenin, cyclin D1, BAF250a, PTEN, p53, WT1 and the mismatch repair (MMR) proteins MLH1, PMS2, MSH2 and MSH6. The results were correlated with KRAS mutation analysis and the presence of concurrent endometriosis. RESULTS: Abnormal ß-catenin, cyclin D1, BAF250a, PTEN, p53 and MMR protein expression was identified in 61.2%, 50.7%, 19.4%, 23.9%, 9.0%, and 6.0% of cases, respectively; these changes were equally common in endometriosis positive and negative tumours. WT1 expression was restricted to endometriosis negative EOC (8/32, 25%) and four WT1 positive cases showed sertoliform/spindle cell histological patterns. Abnormal ß-catenin expression correlated with cyclin D1 overexpression but was inversely related to KRAS mutation. Immunophenotypic abnormalities were present in four of 17 histologically benign endometriotic lesions. CONCLUSIONS: Most immunophenotypic alterations were equally common in endometriosis associated and independent OECs but only the latter were associated with abnormal WT1 expression. The inverse relationship between abnormal ß-catenin expression and KRAS mutation merits further study. Histologically benign endometriotic epithelium may show immunophenotypic abnormalities similar to those present in associated carcinomas.

Interobserver variability in the diagnosis of circumscribed sebaceous neoplasms of the skin.

AIMS: Separation of sebaceous adenoma, sebaceoma and well differentiated sebaceous carcinoma is a clinically important distinction which relies on a number of subjective criteria. In routine practice we had noted significant interobserver variability in the classification of these lesions. This study sought to determine the degree of interobserver variability between general surgical pathologists and dermatopathologists in the diagnosis of well differentiated cutaneous sebaceous neoplasms. METHODS: We circulated 61 examples of well circumscribed cutaneous sebaceous neoplasms to nine pathologists, including dermatopathologists and general surgical pathologists who were asked to submit a diagnosis for each case. Fleiss' kappa statistic was used for assessment of interobserver agreement. RESULTS: We found that only seven cases (11%) had consensus agreement across all nine pathologists. Many cases had multiple diagnoses suggested, with three or more submitted diagnoses in 26 cases (43%), while 38 cases (62%) were diagnosed as sebaceous carcinoma by at least one pathologist. There was marked variability amongst the individual pathologists in the proportion of cases diagnosed as carcinoma, ranging from 5% to 57% of cases. Fleiss' kappa statistic for all pathologists across all diagnostic categories was 0.44, amounting to only fair to moderate agreement. CONCLUSIONS: These data indicate that there is substantial interobserver variability in the diagnosis of well circumscribed sebaceous neoplasms. This was seen in both the separation of benign and malignant lesions, as well as in the classification of the benign entities. This interobserver variability is likely to have significant clinical implications in terms of potential for over- or under-treatment, as well as in selection of cases for mismatch repair protein evaluation.

Post-radioembolization yttrium-90 PET/CT - part 2: dose-response and tumor predictive dosimetry for resin microspheres.

BACKGROUND: Coincidence imaging of low-abundance yttrium-90 (90Y) internal pair production by positron emission tomography with integrated computed tomography (PET/CT) achieves high-resolution imaging of post-radioembolization microsphere biodistribution. Part 2 analyzes tumor and non-target tissue dose-response by 90Y PET quantification and evaluates the accuracy of tumor 99mTc macroaggregated albumin (MAA) single-photon emission computed tomography with integrated CT (SPECT/CT) predictive dosimetry. METHODS: Retrospective dose quantification of 90Y resin microspheres was performed on the same 23-patient data set in part 1. Phantom studies were performed to assure quantitative accuracy of our time-of-flight lutetium-yttrium-oxyorthosilicate system. Dose-responses were analyzed using 90Y dose-volume histograms (DVHs) by PET voxel dosimetry or mean absorbed doses by Medical Internal Radiation Dose macrodosimetry, correlated to follow-up imaging or clinical findings. Intended tumor mean doses by predictive dosimetry were compared to doses by 90Y PET. RESULTS: Phantom studies demonstrated near-perfect detector linearity and high tumor quantitative accuracy. For hepatocellular carcinomas, complete responses were generally achieved at D70 > 100 Gy (D70, minimum dose to 70% tumor volume), whereas incomplete responses were generally at D70 < 100 Gy; smaller tumors (<80 cm3) achieved D70 > 100 Gy more easily than larger tumors. There was complete response in a cholangiocarcinoma at D70 90 Gy and partial response in an adrenal gastrointestinal stromal tumor metastasis at D70 53 Gy. In two patients, a mean dose of 18 Gy to the stomach was asymptomatic, 49 Gy caused gastritis, 65 Gy caused ulceration, and 53 Gy caused duodenitis. In one patient, a bilateral kidney mean dose of 9 Gy (V20 8%) did not cause clinically relevant nephrotoxicity. Under near-ideal dosimetric conditions, there was excellent correlation between intended tumor mean doses by predictive dosimetry and those by 90Y PET, with a low median relative error of +3.8% (95% confidence interval, -1.2% to +13.2%). CONCLUSIONS: Tumor and non-target tissue absorbed dose quantification by 90Y PET is accurate and yields radiobiologically meaningful dose-response information to guide adjuvant or mitigative action. Tumor 99mTc MAA SPECT/CT predictive dosimetry is feasible. 90Y DVHs may guide future techniques in predictive dosimetry.