Oncology-specific radiation dose and image noise reference levels in adult abdominal-pelvic CT.

OBJECTIVES: To provide our oncology-specific adult abdominal-pelvic CT reference levels for image noise and radiation dose from a high-volume, oncologic, tertiary referral center. METHODS: The portal venous phase abdomen-pelvis acquisition was assessed for image noise and radiation dose in 13,320 contrast-enhanced CT examinations. Patient size (effective diameter) and radiation dose (CTDIvol) were recorded using a commercial software system, and image noise (Global Noise metric) was quantified using a custom processing system. The reference level and range for dose and noise were calculated for the full dataset, and for examinations grouped by CT scanner model. Dose and noise reference levels were also calculated for exams grouped by five different patient size categories. RESULTS: The noise reference level was 11.25 HU with a reference range of 10.25-12.25 HU. The dose reference level at a median effective diameter of 30.7 cm was 26.7 mGy with a reference range of 19.6-37.0 mGy. Dose increased with patient size; however, image noise remained approximately constant within the noise reference range. The doses were 2.1-2.5 times than the doses in the ACR DIR registry for corresponding patient sizes. The image noise was 0.63-0.75 times the previously published reference level in abdominal-pelvic CT examinations. CONCLUSIONS: Our oncology-specific abdominal-pelvic CT dose reference levels are higher than in the ACR dose index registry and our oncology-specific image noise reference levels are lower than previously proposed image noise reference levels. ADVANCES IN KNOWLEDGE: This study reports reference image noise and radiation dose levels appropriate for the indication of abdomen-pelvis CT examination for cancer diagnosis and staging. The difference in these reference levels from non-oncology-specific CT examinations highlight a need for indication-specific, dose index and image quality reference registries.

Response criteria for immunotherapy and the radiologic patterns of immune-related adverse events.

Immunotherapy has revolutionized clinical outcomes in both early-stage and advanced-stage malignancies. Immunotherapy has improved patient survival in both solid and hematologic disorders with the potential added benefit of less toxicity compared to conventional cytotoxic chemotherapy. Imaging plays a fundamental role in monitoring treatment response and assessment of immune-related adverse events, e.g. pneumonitis, colitis, etc. Familiarity with the current strategies of immune-related response evaluation and their limitations is essential for radiologists to guide clinicians with their treatment decisions. Radiologists should be aware of the wide spectrum of immune-related adverse events and their various radiological features as well as the patterns of treatment response associated with immunotherapies.

Enhanced survival in perineural invasion of pancreatic cancer: an in vitro approach.

Pancreatic cancer (PanCa) is characterized by perineural invasion (PNI), early lymph node and liver metastasis, and poor prognosis. PNI is one of the important causes of local recurrence. Little is known about the mechanism of PNI in PanCa. We presented a novel model system that may shed light on the mystery of PNI in PanCa. In this study, mouse dorsal root ganglia (DRGs) and human PanCa cell line (MIA PaCa-2) were cocultured in Matrigel matrix (BD Biosciences, San Jose, CA) to build this PNI model. MIA PaCa-2 cell line alone (control 1) or DRG alone (control 2) was cultured with Matrigel matrix as controls. Neurite outgrowth, cell colony growth, neurite-colony contact, and retrograde extension were observed under inverted microscopy and then were photographed and quantitated with the Optimas imaging system (Optimas Corp., Bothell, MA). At day 14, both the experimental and control 2 samples were harvested and subjected to total RNA isolation and fixed in paraffin-embedded blocks. Slides cut from paraffin blocks were studied with Ki-67 immunostaining and TUNEL assay. Gene profiling was performed using complementary DNA microarray. Overexpressed target genes were verified by quantitative reverse transcriptase polymerase chain reaction. The results showed that reciprocity was observed between neurites and MIA PaCa colonies with 24 hours of coculture. Neurite outgrowth was stimulated in the presence of pancreatic carcinoma cells, which showed 2-fold more area than did control 2. After 72 hours, MIA PaCa colonies cocultured with DRG exhibited 58% more colony area than did control 1. The Ki-67 index of the DRG/MIA PaCa cells (mean, 5.02%) was significantly higher than that in control 1 (mean, 1.18%) (P < .05); in contrast, the apoptotic index in the DRG/MIA PaCa cells was significantly lower (mean, 0.45%) than that in the control 1 (mean, 1.85%) (P < .001). Prosurvival genes MALT1 and TRAF were increased 2-fold in DRG/MIA PaCa compared with controls. We demonstrated that neural-epithelial interaction is a mutually beneficial process for the growth of nerves and PanCa cells. It is possible that oncogenes and growth factors might act synergistically in promoting proliferation and/or inhibiting apoptosis, a survival strategy crucial to the development of PNI in PanCa.