Kenta Hakozaki

FDG-PET/CT in the diagnosis of recurrent breast cancer

Background An advantage of PET/CT has been demonstrated for diagnosis of several tumor entities. In patients with breast cancer, early diagnosis and accurate restaging of recurrence after surgery is important for selection of the most appropriate therapeutic strategy. Purpose To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG), for follow-up of patients with suspected recurrent breast cancer. Material and Methods Forty-seven patients with suspected recurrent breast cancer underwent PET/CT. The PET and PET/CT images were interpreted without knowledge of the results of other diagnostic modalities, and compared with each other with reference to the final diagnosis. Results Twenty-five (53%) patients suffered tumor recurrence. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 96%, 91%, 92%, 95%, and 94%, respectively. In comparison with PET, PET/CT had a higher sensitivity and accuracy (96% vs. 80% and 94% vs. 81%, respectively). The difference in diagnostic accuracy between PET/CT and PET was significant (P < 0.05). Conclusion The present findings indicate that PET/CT is an accurate, sensitive and reliable modality for screening and detection of breast cancer recurrence. PET/CT appears to be an effective surveillance tool, as it is able to cover the whole body in a single procedure and shows good performance.

Anemia and the risk of contrast-induced nephropathy in patients with renal insufficiency undergoing contrast-enhanced MDCT

PURPOSE The purpose of this study was to assess the effect of anemia on the incidence of contrast-induced nephropathy (CIN) in patients with renal impairment undergoing MDCT. MATERIALS AND METHODS Institutional review board approval was waived for this retrospective review of 843 patients with stable renal insufficiency (eGFR between 15 and 60 mL/min) who had undergone contrast-enhanced MDCT. Baseline hematocrit and hemoglobin values were measured. Serum creatinine (SCr) was assessed at the baseline and at 48-72 h after contrast administration. RESULTS The overall incidence of CIN in the patient population with renal insufficiency was 6.9%. CIN developed in 7.8% (54 of 695) of anemic patients, and in 2.8% (4 of 148) of non-anemic patients (P=.027). After adjustment for confounders, low hemoglobin and low hematocrit values remained independent predictors of CIN (odds ratio 4.6, 95% CI 1.0-20.5, P=.046). CONCLUSIONS Anemia is associated with a higher incidence of CIN in patients with renal insufficiency. Anemia is a potentially modifiable risk factor for CIN, and has an unfavorable impact on prognosis in patients with renal insufficiency undergoing contrast-enhanced MDCT.

Urinary Excretion of Vasoactive Factors following Contrast Media Exposure in Humans

Background: Radiographic contrast media (CM) induce renal vasoconstriction and may initiate induced nephropathy. Endothelin (ET), a vasoconstrictor, and nitric oxide (NO), a vasodilator, which are synthesized in the kidney by the vascular endothelium as well as by tubular epithelial and glomerular mesangial cells, are key modulators of renal circulation after CM administration. Intravascular CM, in addition, induces pronounced diuresis and natriuresis. The aim of the present study was to evaluate and compare changes in endogenous vasoactive mediators and contrast-induced natriuresis after CM administration. Methods: Diagnostic angiographic procedures were performed in 14 patients (9 males and 5 females) using the non-ionic CM Iopamidol. Before and immediately after angiography, venous blood and urine samples were obtained. The urinary excretion of ET-1 and nitrates/nitrites (NOx), and the fractional excretion of sodium (FENa) were measured and analyzed. Results: The urinary excretion of both ET-1 and NOx increased significantly (p < 0.05) after angiography, and urinary ET-1 and NOx excretion was correlated with an increase in FENa (p < 0.05). Conclusion: Exposure to CM in humans is associated with an increase in urinary ET and NOx. The excretion of sodium following CM administration is associated with an increase in urinary ET and NOx. ET and NO might be important in the renal change in humans after CM administration.

Validation of fast-RAMLA in clinical PET

ObjectiveImages using the fast row action maximum likelihood algorithm (fast-RAMLA), which employs half-interpolated sinograms of conventional 3DRAMLA, are immediately generated following positron emission tomography (PET) scanning and are invariably produced in the process of line-of-response RAMLA (LOR-RAMLA) reconstruction. We quantitatively and visually compared the clinical validity of dual time point [18F]-FDG imaging with fast-RAMLA and LOR-RAMLA.MethodsAn International Electrotechnical Commission (IEC) phantom was established in which the ratio of the activities in the hot sphere was set up and a background of 3.8:1 was scanned and reconstructed using both algorithms. The contrast recovery coefficient was then calculated. The clinical study retrospectively analyzed 35 patients (25 men and 10 women; age range 30–84 years; mean age 63.9 years) with confirmed specific pathological lesions or clinical follow-up; 21 of the patients had 51 malignant lesions and 15 had 23 benign lesions. The maximum standard uptake value (SUVmax) was measured in all lesions using LOR-RAMLA. The maximal counts of all lesions determined manually were divided by the average count of bilateral ventricles and the aortic arch for standardization on fast-RAMLA, and the values were compared with the SUVmax of LORRAMLA. Inter-observer variation in detection was determined among three radiologists who blindly reviewed and scored 70 maximum intensity projection images from 35 patients reconstructed using LORRAMLA and fast-RAMLA.ResultsWe identified a quantitative correlation and determined the visual quality of lesion detection between fast-RAMLA and LOR-RAMLA and indicated usefulness and improvement point on fast-RAMLA.ConclusionsFast-RAMLA can improve the strategy for using dual time point [18F] fluorodeoxyglucose positron emission tomography ([18F]-FDG-PET) and increase the efficiency of the [18F]-FDG-PET scanner.