Preoperative assessment of peritoneal carcinomatosis: intraindividual comparison of 18F-FDG PET/CT and MRI.

OBJECTIVE: Exact determination of localization and extent of peritoneal carcinomatosis (PC) before peritonectomy and hyperthermic intraperitoneal chemotherapy (HIPEC) is crucial for the clinical outcome. Our study compares dynamic contrast enhanced 3D MRI (T1wDCE) and 18F-FDG PET/CT regarding diagnostic accuracy in correlation with surgical exploration (SE) and histological (HI) results. MATERIALS AND METHODS: 15 patients with PC were examined on a 1.5T MRI and 16 slice PET/CT. MRI: coronal T1wDCE covering the complete abdomen (0.15 mmol Gd-chelate/kg BW, 2000 mL mannitol solution p.o., 40 mg buscopan i.v.). PET-CT: contrast enhanced 16slice CT (120 mL ultravist 370 i.v., 1000 mL mannitol solution p.o., 40 mg buscopan i.v.), PET: 350 MBq 18-FDG i.v., 3 min acquisition time/bed, 60 min after tracer injektion). Assessment by two independent, experienced observers in correlation with results of SE and HI for each abdominal segment based on the peritoneal cancer index (PCI) proposed by Sugarbaker and co-authors. RESULTS: MRI and PET/CT provided reliable detection of PC. One patient had to be excluded from statistical analysis. In summary, 182 segments were assessed (13/patient, 14 patients, one patient excluded from statistical analysis). PC was found in 118 by MRI, 124 by PET/CT. 4 segments were classified false positive for MRI, 2 for PET/CT. False negative segments (MRI: 17, PET/CT: 9) did not result in irresectability. Positive predictive value for PC/segment was 97/98%, negative predictive value 73/84%, sensitivity 87/93%, specificity 92/96%, and diagnostic accuracy 88/94% (MRI/PET/CT). CONCLUSION: With high diagnostic accuracy for PC of both, MRI and PET/CT, PET/CT provides better diagnostic accuracy and especially better NPV.

Peritoneal carcinomatosis: comparison of dynamic contrast-enhanced magnetic resonance imaging with surgical and histopathologic findings.

OBJECTIVE: In patients with peritoneal carcinomatosis (PC) accurate preoperative assessment is essential to determine indication and surgical procedure to ensure optimal outcome. Purpose of our study was to assess the diagnostic accuracy (DA) of multiphasic dynamic contrast-enhanced MRI to determine the extent of PC in correlation with surgical and histopathological findings. MATERIALS AND METHODS: 14 Patients with proven PC were examined on a 1.5T system before peritonectomy and hyperthermic intraperitoneal chemotherapy. Patient preparation included oral application of 2000 mL mannitol solution and 40 mg butylscopolaminiumbromid i.v. Coronal contrast-enhanced multiphasic dynamic T1w 3D gre sequences (T1W DCE) (0.15 mmol Gd-chelate/kg bw) covering the whole abdomen were acquired (TR 2.9 ms, TE 1.1 ms, resolution 2.0 × 2.0 × 1.8 mm, FOV 400 × 400 mm). MRI was assessed by two radiologists and correlated with surgical exploration (SE) and histopathology for each segment based on the peritoneal cancer index proposed by Sugarbaker et al. RESULTS: In total, 182 segments were evaluated. PC was found in 118/121 of 182 segments (reader 1/2) by MRI and in 131 segments by SE. In 4/7 segments MRI was false positive. False negative segments 17/17 in MRI did not result in irresectability. The positive predictive value for PC per segment of MRI was 97%/94%, the negative predictive value 73%/72%, the sensitivity 87%/87% and the specificity 92%/86%. The DA was 88%/87%. CONCLUSION: T1W DCE is an accurate and clinical valuable tool for the preoperative assessment of peritoneal tumor spread.

Tumor-infiltrating immune cells promoting tumor invasion and metastasis: existing theories.

It is a commonly held belief that infiltration of immune cells into tumor tissues and direct physical contact between tumor cells and infiltrated immune cells is associated with physical destructions of the tumor cells, reduction of the tumor burden, and improved clinical prognosis. An increasing number of studies, however, have suggested that aberrant infiltration of immune cells into tumor or normal tissues may promote tumor progression, invasion, and metastasis. Neither the primary reason for these contradictory observations, nor the mechanism for the reported diverse impact of tumor-infiltrating immune cells has been elucidated, making it difficult to judge the clinical implications of infiltration of immune cells within tumor tissues. This mini-review presents several existing hypotheses and models that favor the promoting impact of tumor-infiltrating immune cells on tumor invasion and metastasis, and also analyzes their strength and weakness.