Can We Predict Bleomycin Toxicity with PET-CT?

AIM: Bleomycin is an antitumor antibiotic used successfully to treat a variety of malignancies, predominantly germ cell tumors and Hodgkin's lymphoma (HL). The major limitation of bleomycin therapy is the potential for life-threatening interstitial pulmonary fibrosis. Early identification of asymptomatic patients who may develop toxicity is important. We aimed to evaluate fluorodeoxyglucose positron-emission tomography (FDG-PET/CT) findings to predict bleomycin toxicity (BT) early after chemotherapy with doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD) chemotherapy before clinical symptoms and radiological changes occur. MATERIALS AND METHODS: HL patients who were treated with ABVD were evaluated. SUVmax values of lung parenchyma were analyzed in FDG-PET/CT at diagnosis and after 4 cycles of chemotherapy in all patients. At the end of the chemotherapy cycles, lung parenchymal SUVmax values of patients with BT and without BT were compared statistically. RESULTS: Twenty (66.7%) male and 10 (33.3%) female patients with HL were included. Five (16.7%) HL patients developed BT. In 3 HL patients, BT was determined after 5 cycles and in 2 patients, BT was seen after 6 cycles. In all 5 of these patients with BT, FDG uptake in PET-CT was increased after 4 cycles of chemotherapy and BT was predicted before clinical and radiological findings by FDG-PET/CT. After 4 cycles of chemotherapy, lung parenchymal SUVmax of patients with BT (3.24 ± 0.76) was significantly higher than in patients without toxicity (1.84 ± 0.52) (p < 0.001). In patients with BT, a significant increase was established in lung parenchymal SUVmax after 4 cycles of chemotherapy when compared to the time of diagnosis (p = 0.043). CONCLUSION: BT can be fatal. Early detection of BT is essential in clinical practice. FDG-PET/CT can predict BT before clinical and radiological findings occur.

Pulmonary 18F-FDG microembolism detected on only delayed image in a PET/CT study.

Focal 18F-FDG pulmonary uptake on PET without corresponding abnormality on CT is an incidental and rare finding. This artifact is associated with iatrogenic FDG microembolus as a result of vascular endothelium damage during injection. We present a pulmonary FDG microembolus in a patient evaluated for suspicion of gallbladder cancer not in early (standard 1-hour imaging after FDG injection) but in delayed image. To our knowledge, this is the first case that describes the possibility of FDG microembolism on only delayed image in a PET/CT study.

Reduced heart rate response to dipyridamole in patients undergoing myocardial perfusion SPECT.

OBJECTIVE: A mild decrease in blood pressure and increase in heart rate (HR) are considered normal hemodynamic responses to dipyridamole. In this study, we tried to investigate HR response to dipyridamole and its predictors in patients undergoing gated myocardial perfusion single photon emission computed tomography (SPECT). METHODS: 201 consecutive patients undergoing dipyridamole stress Tc99m-MIBI or Tl-201 gated myocardial perfusion SPECT were prospectively enrolled. Dipyridamole was infused over 4 min and radiopharmaceutical was injected 3 min after the end of infusion. A reduced heart rate response to dipyridamole considered if the HR ratio (peak HR/rest HR) was 1.20 or less. Stress (sLVEF), rest (rLVEF) left ventricular ejection fractions, stress and rest motion (SMS, RMS) and thickening scores (STS, RTS) were derived automatically by QGS. Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion were calculated. Patients were grouped according to HR response and groups were compared. A logistic regression analysis was used to determine independent predictors of reduced HR response. RESULTS: Reduced HR response was found in 78 % of patients. Patients with abnormal HR response were more frequently had a history of diabetes mellitus, chronic renal failure, and had lower high-density lipoprotein (HDL) levels. Peak HR, SSS, SRS, sLVEF and rLVEF were lower; rest HR, RTS, and the number of patients with ≤ 45 % sLVEF and rLVEF were higher in reduced HR response group (all p < 0.05). There was no difference between groups by means of gender, rest and peak systolic or diastolic tension, SDS, SMS, STS, RMS, history of hypertension, peripheral arterial disease, metabolic syndrome, coronary interventions, digoxin, calcium channel blocker or beta blocker usage. Multivariable logistic regression analysis demonstrated that the independent predictors of reduced HR response were HDL, rest HR and SSS. When HDL was removed from the model, chronic renal failure also emerged as an independent predictor. CONCLUSION: Reduced HR response to dipyridamole is associated with ventricular dysfunction, cardiac autonomic neuropathy. Low HDL levels also seem to be related with reduced HR response.