Quantitative and qualitative comparison of Rubidium-82 and Oxygen-15 water cardiac PET.

BACKGROUND: Differences in tracer characteristics may influence the interpretation of positron emission tomography myocardial perfusion imaging (MPI). We compare the reading of MPIs with a low-extraction retention tracer (82Rb) and a high-extraction non-retention tracer (15O-water) in a selected cohort of patients with known coronary artery disease (CAD). METHODS: Thirty-nine patients with known CAD referred to 82Rb MPI due to angina underwent rest and stress imaging with both tracers and experienced MPI readers provided blinded consensus reads of all studies. In addition, a comparison of regional and global quantitative measures of perfusion was performed. RESULTS: The results showed 74 % agreement in the reading of 82Rb and 15O-water MPI for regional reversible ischemia and global disease, and 82 % agreement for regional irreversible ischemia. The 15O-water MPI identified more cases of global disease (n = 12 (15O-water) vs n = 4 (82Rb), p = 0.03), whereas differences in reversible ischemia (n = 22 vs n = 16, p = 0.11) and, irreversible ischemia (n = 8 vs n = 11, p = 0.45) were not significant. The correlation between myocardial blood flow measured using the two tracers was similar to previous studies (R2 = 0.78) with wide limits of agreement (-0.93 to 0.84 ml/g/min). CONCLUSIONS: Agreement between consensus readings of 82Rb and 15O-water MPI was good in patients with known CAD. In this limited size study, no significant differences in the identification of reversible and irreversible ischemia found, whereas 15O-water MPI had a higher positive rate for suspected global disease.

Incidental FDG-Avid Focuses in Palatine Tonsils on PET/CT.

OBJECTIVES: The management of incidental findings of FDG-avid tonsils on PET/CT (IFT) is unclear. We aimed to explore the prevalence of malignancy in IFT, identify risk factors for malignancy, and calculate optimal cutoffs of maximum standardized uptake values (SUVmax ) to discriminate between benign and malignant lesions. METHODS: All patients who were tonsillectomized at our institution because of IFT from October 2011 to December 2020 were included. Patients undergoing PET/CT due to suspected tonsillar disease or cancer of unknown primary were excluded. RESULTS: In total, 77 patients were included, of which 11 (14%) of them had IFT malignancy. Dysphagia (p = 0.019) and alcohol abuse (p = 0.035) were associated with malignancy. Absolute SUVmax cutoff (≥9: sensitivity 100%; specificity 53%) was superior to SUVmax side-to-side ratio (≥1.5: sensitivity 64%; specificity 70%) to discriminate between benign and malignant lesions. CONCLUSION: We recommend tonsillectomy for patients with IFT displaying SUVmax ≥ 9.0, ratio ≥ 1.5, or symptoms or findings suggesting malignancy. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:2370-2378, 2022.

DAHANCA 10 - Effect of darbepoetin alfa and radiotherapy in the treatment of squamous cell carcinoma of the head and neck. A multicenter, open-label, randomized, phase 3 trial by the Danish head and neck cancer group.

PURPOSE: To evaluate if correction of low hemoglobin (Hb) levels by means of darbepoetin alfa improves the outcomes of radiotherapy in patients with squamous cell carcinoma of the head and neck (HNSCC). PATIENTS AND METHODS: Patients eligible for primary radiotherapy and who had Hb values below 14.0 g/dl were randomized to receive accelerated fractionated radiotherapy with or without darbepoetin alfa. Patients also received the hypoxic radiosensitizer nimorazole. Darbepoetin alfa was given weekly during radiotherapy or until the Hb value exceeded 15.5 g/dl. RESULTS: Following a planned interim analysis which showed inferiority of the experimental treatment the trial was stopped after inclusion of 522 patients (of a planned intake of 600). Of these, 513 were eligible for analysis (254 patients treated with darbepoetin alfa and 259 patients in the control group). Overall, the patients were distributed according to the stratification parameters (gender, T and N staging, tumor site). Treatment with darbepoetin alfa increased the Hb level to the planned value in 81% of the patients. The compliance was good without excess serious adverse events. The results showed a poorer outcome with a 5-year cumulative loco-regional failure rate of 47% vs. 34%, Hazard Ratio (HR): 1.53 [1.16-2.02], for the darbepoetin alfa vs. control arm, respectively. This was also seen for the endpoints of event-free survival (HR: 1.36 [1.09-1.69]), disease-specific death (HR: 1.43 [1.08-1.90]), and overall survival (HR: 1.30 [1.02-1.64]). There was no enhanced risk of cardio-vascular events observed in the experimental arm or any significant differences in acute or late radiation related morbidity. All univariate analyses were confirmed in a multivariate setting. CONCLUSION: Correction of the Hb level with darbepoetin alfa during radiotherapy of patients with HNSCC resulted in a significantly poorer tumor control and survival.

Effect of remote ischemic conditioning on myocardial perfusion in patients with suspected ischemic coronary artery disease.

BACKGROUND: Remote ischemic conditioning (RIC) confers protection against myocardial ischemia-reperfusion injury and may modulate coronary blood flow. We investigated whether RIC affects resting myocardial perfusion (MP) in patients with suspected ischemic coronary artery disease by quantitative MP imaging. METHODS AND RESULTS: We included 49 patients with suspected ischemic coronary artery disease. Resting MP was quantified by 82Rubidium positron emission tomography/computed tomography (82Rb-PET/CT) imaging before and after RIC, performed as four cycles of 5 minutes upper arm ischemia and reperfusion. Subsequent adenosine 82Rb-PET/CT stress-imaging identified non-ischemic and reversibly ischemic myocardial segments. MicroRNA-144 plasma levels were measured before and after RIC. Normalized for rate pressure product, RIC did not affect MP globally (P = .64) or in non-ischemic myocardial segments (P = .58) but decreased MP in reversibly ischemic myocardial segments (-0.11 mL/min/g decrease in MP following RIC; 95% CI -0.17 to -0.06, P < .001). However, we found no effect of RIC when MP was normalized for cardiac work. MicroRNA-144 plasma levels increased following RIC (P = .006) but did not correlate with a change in global MP in response to RIC (P = .40). CONCLUSIONS: RIC did not substantially affect resting MP globally or in non-ischemic and reversibly ischemic myocardial territories in patients with suspected ischemic coronary artery disease.

Effect of smoking on oxygen delivery and outcome in patients treated with radiotherapy for head and neck squamous cell carcinoma--a prospective study.

BACKGROUND: Head and neck cancer patients with high hemoglobin respond better to irradiation compared to patients with low hemoglobin possibly due to hypoxia induced radioresistance. The hemoglobin level is, however, a crude indicator of the amount of oxygen available to the tissue and may be influenced by a number of factors, smoking being of potential importance. The aim of the present study was to examine the effect of smoking on available oxygen to tumors and the effect on outcome in head and neck cancer patients treated with radiotherapy in a prospective study. MATERIALS AND METHODS: A total of 232 consecutive patients with squamous cell carcinoma of the larynx, pharynx and oral cavity completed questionnaires on smoking habits prior to treatment. Venous blood samples were collected before and/or during treatment to determine the hemoglobin and carboxyhemoglobin level. Patients were treated with primary curative radiotherapy 62-68 Gy, 2 Gy/fx, 5 fx/week. RESULTS: All but 12 patients had a history of smoking, 35 were long term quitters, 23 recent quitters, 54 moderate smokers and 108 heavy smokers (>1 pack/day). There was no relationship between total hemoglobin and carboxyhemoglobin, but effective hemoglobin and carboxyhemoglobin were linearly correlated. The amount of carboxyhemoglobin increased with increasing smoking status. Actuarial 5-year univariate analysis showed that heavy smokers had a significantly reduced probability of loco-regional control (44% vs. 65%, p = 0.001), disease-specific (56% vs. 77%, p = 0.003) and overall survival (39% vs. 66%, p = 0.0004) compared to non-smoking patients. Multivariate analyses showed that patients characterized as non-smokers, with low T and N classifications and high hemoglobin level had the best outcome measurements. A rise in carboxyhemoglobin significantly decreased the probability of loco-regional control and each additional pack year increased the risk of death. Smokers and former smokers develop secondary cancers. CONCLUSION: The study showed a significant negative impact of smoking during radiotherapy for head and neck cancer and the risk of death was increased with each additional pack year of smoking. The effect on loco-regional control could be explained by a rise in carboxyhemoglobin level in smokers, e.g. a reduced oxygen supply to tumors. The data strongly advocate that smoking should be avoided in order to improve the therapeutic efficacy of radiotherapy and development of other smoking-related diseases and/or secondary cancers.

Importance of hemoglobin concentration and its modification for the outcome of head and neck cancer patients treated with radiotherapy.

INTRODUCTION: Hypoxia induced radioresistance has been acknowledged for decades. One of the indirect evidences of the influence of hypoxia on radiation response comes from the observations of a correlation between tumor control and hemoglobin level. This review examines the clinical data on the prognostic and predictive role of hemoglobin level and hemoglobin manipulation in radiotherapy of squamous cell carcinomas of the head and neck, a tumor type where hypoxic radioresistance have been previously documented. THE INFLUENCE OF HEMOGLOBIN CONCENTRATION ON TUMOR OXYGENATION AND OUTCOME: The aim is to evaluate the existing literature for information of the influence of hemoglobin concentration and hemoglobin modifications on tumor oxygenation and outcome in head and neck squamous cell cancer patients. The data from several randomized trials show that while most studies have confirmed the prognostic value of hemoglobin, increasing the hemoglobin level through transfusion or erythropoietin stimulation did not result in improved outcome for patients with low initial hemoglobin levels. Clinical studies showed that smoking reduced the oxygen carrying capacity of the blood through formation of carboxyhemoglobin, and lead to poorer response to radiotherapy in smokers compared to non-smokers. Smoking also increased the risk of the development of secondary cancers. CONCLUSION AND FUTURE PERSPECTIVES: In conclusion, low hemoglobin is a significant negative prognostic factor for radiotherapy of head and neck cancer. Correction of pre-treatment low hemoglobin by blood transfusion and/or erythropoietin stimulating agents does, however, not improve the outcome. Smoking leads to a decrease in effective hemoglobin and poorer treatment outcome. Smoking should be avoided in order to improve the therapeutic efficacy of radiotherapy and development of other smoking-related diseases and/or secondary cancers.

Does transfusion improve the outcome for HNSCC patients treated with radiotherapy? - results from the randomized DAHANCA 5 and 7 trials.

BACKGROUND: Patients with head and neck squamous cell carcinoma (HNSCC) and a low level of hemoglobin often have a poor response to radiation that may be related to hypoxia-induced radioresistance. We have previously published the importance of hemoglobin level and the effect of transfusion by the results from the randomized DAHANCA 5 trial, including 414 patients in the analysis. Aim of the current analysis was to gain additional power by adding patients from the continued subrandomization in the DAHANCA 7 trial, now including a total of almost 1200 patients. MATERIAL AND METHODS: Patients were randomized to treatment in the DAHANCA 5 and 7 study (nimorazole vs. placebo and five fx/week vs. six fx/week), and in addition, patients with "low" pre-irradiation hemoglobin values (females <13 g/dl; males <14.5 g/dl) were subrandomized to plus or minus transfusion. Transfusion was given with packed red blood cells with the aim to achieve a hemoglobin level in the "high" value range. RESULTS: A total of 1166 patients were included, 701 patients had high hemoglobin levels and 465 had low hemoglobin levels. Among the low hemoglobin patients, 235 were randomized to receive transfusion. Patient characteristics and treatment arms were well balanced. In the majority of patients, transfusion resulted in increased hemoglobin levels although this decreased slightly throughout treatment as in the non-transfused patients. Overall, the patients with low hemoglobin level had a significant reduced probability of locoregional control, disease-specific and overall survival. In the low hemoglobin group, transfusion did not improve the outcome in locoregional control, disease-specific or overall survival. In multivariate analyses, HPV/p16 status, T and N classification were significant factors for all outcome measures, whereas there was no significant influence of transfusion or hemoglobin level on endpoints. CONCLUSION: Transfusion prior to and during radiation treatment did not improve the outcome in patients with HNSCC and low hemoglobin values, but may have a negative impact on survival.

The importance of haemoglobin level and effect of transfusion in HNSCC patients treated with radiotherapy--results from the randomized DAHANCA 5 study.

BACKGROUND AND PURPOSE: Patients with head and neck squamous cell carcinoma (HNSCC) and a low level of haemoglobin (Hb) often have a poor response to radiation which may be related to hypoxia induced radioresistance. The aim of the study was to evaluate the prognostic significance of low Hb level and its modification by transfusion in HNSCC patients treated with radiotherapy. The study was performed as a subrandomization in the DAHANCA 5 trial. MATERIAL AND METHODS: Patients were randomized to treatment with the hypoxic radiosensitizer nimorazole or placebo, and in addition, patients with "low" pre-irradiation Hb values (females<13 g/dL; males<14.5 g/dL) were subrandomized to plus or minus transfusion. Transfusion was given with packed red blood cells with the aim to achieve a Hb level in the "high" value range. RESULTS: A total of 414 patients were included, 243 patients had high Hb levels and 171 patients had low Hb levels. Of the low Hb patients, 82 were randomized to receive transfusion and 89 not to receive transfusion. The treatment arms were well balanced. In the majority of patients, transfusion resulted in increased Hb levels although this tended to decline throughout treatment. Patients with high Hb levels had a significantly better probability of locoregional control, disease-specific survival and overall survival compared to 'low Hb no transfusion' patients. In the low Hb group, transfusion did not improve the outcome in locoregional control, disease-specific survival or overall survival. In multivariate analyses, T and N classifications were significant for all outcome measures, whereas there was no significant influence of transfusion or Hb level on endpoints. CONCLUSION: The univariate prognostic significance of high Hb level was demonstrated in patients with HNSCC treated with radiotherapy; however, transfusion prior to and during treatment did not improve the outcome in patients with low Hb values.