Robustness versus disease differentiation when varying parameter settings in radiomics features: application to nasopharyngeal PET/CT.

OBJECTIVES: To investigate the impact of parameter settings as used for the generation of radiomics features on their robustness and disease differentiation (nasopharyngeal carcinoma (NPC) versus chronic nasopharyngitis (CN) in FDG PET/CT imaging). METHODS: We studied 106 patients (69/37 NPC/CN, pathology confirmed), and extracted 57 radiomics features under different parameter settings. Robustness was assessed by the intra-class correlation coefficient (ICC). Logistic regression with leave-one-out cross validation was used to generate classification probabilities, and diagnostic performance was assessed by the area under the receiver operating characteristic curve (AUC). RESULTS: Varying averaging strategies and symmetry, 4/26 GLCM features showed poor range of pairwise ICCs of 0.02-0.98, while depicting good AUCs of 0.82-0.91. Varying distances, 5/26 GLCM features showed ICCs of 0.82-0.99 while corresponding AUCs were 0.52-0.91. 6/13 GLRLM features showed both high AUC (0.81-0.89) and high ICC (0.85-0.99) regarding to averaging strategies. 7/13 GLSZM features showed AUCs of 0.81-0.90 while having ICCs of 0.01-0.99 under different neighbourhoods. 2/5 NGTDM features showed AUCs of 0.81-0.85 while having ICCs of 0.19-0.89 for different window sizes. Differentiating a subset of NPC (stages I-II) form CN, both SumEntropy and SZLGE achieved significantly higher AUCs than metabolically active tumour volume (AUC: 0.91 vs. 0.72, p<0.01). CONCLUSIONS: Radiomics features depicting poor absolute-scale robustness regarding to parameter settings can still lead to good diagnostic performance. As such, robustness of radiomics features should not be overemphasized for removal of features towards assessment of clinical tasks. For differentiating NPC from CN, some radiomics features (e.g. SumEntropy, SZLGE, LGZE) outperformed conventional metrics. KEY POINTS: • Poor robustness did not necessarily translate into poor differentiation performance. • Absolute-scale robustness of radiomics features should not be overemphasized. • Radiomics features SumEntropy, SZLGE and LGZE outperformed conventional metrics.

Differentiating suspected nasopharyngeal infection from carcinoma using dual-tracer and multiple time-point technetium-99m sestamibi and white blood cell SPECT/CT imaging.

The role of molecular and functional imaging lies in its capability to more accurately define and characterize pathologies, with a host of varied radiotracers and techniques being available to the clinician for use. We present a case in which dual-tracer and multiple time-point single photon emission computed tomography/computed tomography imaging using technetium-99m sestamibi and white blood cell radiotracers was used to characterize an indeterminate base of skull lesion.

The nasopharynx in oral and maxillofacial radiology. I. Benign lesions.

This is not a comprehensive review of all benign lesions that can be found in the nasopharynx, but merely a review of the relationship of the nasopharynx to its surroundings. It is also a reminder of the need for the oral and maxillofacial radiologist to be familiar with this area, because it often appears on radiographs made for other purposes, or to investigate problems that have extended to and from the nasopharynx and the oral and maxillofacial region.

Radiologic evaluation of the normal adult nasopharynx.

Adenoid hypertrophy complicates the radiographic evaluation of the adult nasopharynx. To define the limits of normal soft-tissue thickness of the nasopharynx on the lateral film, I measured the profiles of 2 different groups of adult patients: 60 patients examined by x-ray for trauma who had no sinus disease or nasopharyngeal complaints and 30 patients examined by x-ray who had nasopharyngeal complaints necessitating biopsies. Histologic examinations of the biopsy specimens indicated benign disease, usually caused by an inflammatory process. The asymptomatic group showed a more uniform appearance of the nasopharynx than the symptomatic patients, who had a wide variation in the thickness of the nasopharynx. The symptomatic group manifested nasal and eustachian tube obstruction, frequently associated with serous otitis media. When the soft-tissue thickness of the nasopharynx was correlated with age, nasopharyngeal thickening was unusual in asymptomatic persons older than 30 years. Conversely, persons over 30 with nasopharyngeal thickening were often symptomatic and had biopsies indicating some inflammatory change in the nasopharynx.