肾脏原发性肿瘤CT 成像进展

肾脏原发性肿瘤种类繁多,多为恶性,且各病理亚型的影像表现均有不同。部分良性肿瘤如乏脂性血管平滑肌脂肪瘤、嗜酸细胞瘤难以与其区分,因此术前明确其组织学类型有助于治疗方案制定以及预后评估。CT是检查肾脏肿瘤的重要影像方法之一,除常规平扫、动态增强检查外,CT灌注成像、能量CT及PET-CT等亦提供了诸多信息。本文就其CT成像现状综述如下。     

Merkel cell carcinoma and 18FDG PET-CT: A case report

Merkel cell carcinoma (MCC) is a neuroendocrine skin tumor with an unpredictable evolution and high metastatic potential. It usually occurs in the elderly people with long-term sun exposure or weak immune systems. The avidity of MCCs for 18F-flourodeoxyglucose justifies the use of positron emission tomography for its staging.     

Resolution-recovery-embedded image reconstruction for a high-resolution animal SPECT system

The small-animal High-Resolution SPECT (HiReSPECT) is a dedicated dual-head gamma camera recently designed and developed in our laboratory for imaging of murine models. Each detector is composed of an array of 1.2 × 1.2 mm² (pitch) pixelated CsI(Na) crystals. Two position-sensitive photomultiplier tubes (H8500) are coupled to each head's crystal. In this paper, we report on a resolution-recovery-embedded image reconstruction code applicable to the system and present the experimental results achieved using different phantoms and mouse scans. Collimator-detector response functions (CDRFs) were measured via a pixel-driven method using capillary sources at finite distances from the head within the field of view (FOV). CDRFs were then fitted by independent Gaussian functions. Thereafter, linear interpolations were applied to the standard deviation (σ) values of the fitted Gaussians, yielding a continuous map of CDRF at varying distances from the head. A rotation-based maximum-likelihood expectation maximization (MLEM) method was used for reconstruction. A fast rotation algorithm was developed to rotate the image matrix according to the desired angle by means of pre-generated rotation maps. The experiments demonstrated improved resolution utilizing our resolution-recovery-embedded image reconstruction. While the full-width at half-maximum (FWHM) radial and tangential resolution measurements of the system were over 2 mm in nearly all positions within the FOV without resolution recovery, reaching around 2.5 mm in some locations, they fell below 1.8 mm everywhere within the FOV using the resolution-recovery algorithm. The noise performance of the system was also acceptable; the standard deviation of the average counts per voxel in the reconstructed images was 6.6% and 8.3% without and with resolution recovery, respectively.     

Que faire devant la découverte d’un nodule pulmonaire solide sur un CT ou un PET-CT

Incidental discovery of pulmonary nodules is a frequent finding on a CT or a PET-CT examination. When found, those nodules should be classified as (1) certainly benign, (2) certainly malignant or (3) undetermined. The purpose of this paper is to present a diagnostic approach allowing such classification.