No abstract

No abstract

BACKGROUND AND PURPOSE:The prevalence and topography of small hypointense foci suggesting microbleeds on 3T SWI in various types of dementia have not been systematically investigated. The purpose of this study was to determine the prevalence and topography of SHF on 3T SWI in patients with different dementia subtypes.

Purpose: To evaluate the impact of 99m Tc-labeled diethylene triamine pentaacetate-galactosyl human serum albumin ( 99m Tc-GSA) single-photon emission computed tomography (SPECT) image-guided inverse planning on the dose–function histogram (DFH) parameters for stereotactic body radiation therapy planning in patients with hepatocellular carcinoma (HCC). Methods: Eleven patients were enrolled in this study. The functional liver structure (FLS) was derived from SPECT thresholds of 60% to 80% of the maximum pixel value. Two treatment plans optimized without FLS (plan C) and with FLS (plan F) were designed for 50 Gy to the planning target volume (PTV). The DFH parameters were calculated as follows: Fx = (sum of the counts within the liver volume receiving a dose > x Gy/sum of the counts within the whole liver volume) × 100. Other parameters for the PTV included D 95 , mean dose, conformity index (CI), and homogeneity index (HI). Results: Compared with plan C, plan F significantly reduced DFH parameters of F 5 to F 40 ( P < .05). There were no significant differences in the parameters of the PTV of D 95 , mean dose, CI, and HI and organs at risks (stomach, duodenum, spinal cord, and kidneys) between plans C and F. Conclusion: DFH analyses revealed that 99m Tc-GSA SPECT image-guided inverse planning provided dosimetric benefits related to sparing of liver function and may reduce hepatic toxicities.

Abstract. Background/Aim: We evaluated the influence of previous treatments on the parametric discrepancies between dose-volume histograms (DVHs) and dose-function histograms (DFHs) generated based on 99m Tc-GSA SPECT images of hepatocellular carcinoma (HCC) patients treated with stereotactic body radiation therapy (SBRTPrimary liver cancer is the third most common cause of cancer death worldwide. Hepatocellular carcinoma (HCC) accounts for 85%-90% of primary liver cancers (1). Stereotactic body radiation therapy (SBRT) for HCC has been introduced as an alternative to standard treatments such as surgical resection and radiofrequency ablation (RFA) (1). SBRT delivers a highly conformal, potent dose of radiation to the tumor in some fractions, while minimizing radiation damage to organs at risk. SBRT provides excellent local control for HCC with a reported control rate of 80-90% (2-4).HCC response to radiation therapy (RT) exhibits a doseresponse relationship (5), but a fine balance is required between delivering a sufficient RT dose to control the HCC and avoiding radiation-induced liver toxicity. Radiationinduced liver injury (RILD), which occurs in 10-20% of HCC patients undergoing SBRT, remains a problematic adverse effect, because of pre-existing liver dysfunctions occurring secondary to comorbid conditions such as hepatitis B/C infection and cirrhosis (3, 4). The percentage of normal liver volume receiving a dose over the threshold dose calculated based on a dose-volume histogram (DVH) is commonly used for determining dose constraints and predicting radiation-induced liver toxicity; however, it has limited predictive ability (6, 7).A drawback of using DVH for SBRT planning in HCC is the lack of functional information because DVHs are generated based on computed tomography (CT) images, which provide only morphological information. A dosefunction histogram (DFH) generated based on single photon emission computed tomography (SPECT) images may facilitate the assessment of the functional status of organs at risk. For treatment planning in lung cancers, Marks et al. (8) performed DFH calculation using 99m Tc-labeled macroaggregated albumin and observed decreases in lung perfusion at, adjacent to, and separate from tumor in 94%, 74%, and 42% of patients, respectively. 99m Tc-labeled diethylene triamine pentaacetate-galactosyl human serum albumin 1511