The predictive value of preoperative 18F-fluorodeoxyglucose PET for postoperative recurrence in patients with localized primary gastrointestinal stromal tumour.

OBJECTIVES: To assess the potential value of preoperative 18F-FDG PET to predict postoperative recurrence of solitary localized primary gastrointestinal stromal tumour (GIST) after radical resection. METHODS: A total of 46 patients with primary GIST who received preoperative 18F-FDG PET and underwent complete resection without neoadjuvant therapy were retrospectively studied. PET findings, including ring-shaped uptake and intense uptake, were compared with Joensuu risk grades using Fisher's exact test. The prognostic value of the preoperative clinico-imaging variables-age ≥60 years, male, ring-shaped uptake, intense uptake, tumour size >5 cm, heterogeneous CT attenuation and lower gastrointestinal origin-and Joensuu high risk for recurrence-free survival was evaluated using log-rank test and multivariate Cox regression analysis. RESULTS: Ring-shaped uptake and intense uptake were significantly associated with Joensuu high risk. Univariate analysis showed that ring-shaped uptake, intense uptake, size >5 cm and Joensuu high risk were significantly associated with inferior recurrence-free survival. Multivariate analysis showed that ring-shaped uptake (P = 0.004) and Joensuu high risk (P = 0.021) were independent adverse prognostic factors of postoperative recurrence. CONCLUSIONS: Ring-shaped uptake on preoperative 18F-FDG PET may be a potential predictor of postoperative tumour recurrence of localized primary GISTs. KEY POINTS: • Clinical course of resectable solitary localized primary GISTs varies widely. • Ring-shaped uptake is an independent adverse prognostic factor of postoperative recurrence. • Preoperative 18 F-FDG PET may help predict postoperative recurrence of GISTs.

Clinical, Morphologic, and Pathologic Features Associated With Increased FDG Uptake in Schwannoma.

OBJECTIVE: The objective of this study was to investigate the clinical, morphologic, and pathologic features associated with increased 18F-FDG uptake in benign schwannomas. MATERIALS AND METHODS: Twenty-two schwannomas in 22 patients (age range, 25-81 years) who had FDG PET or PET/CT scans and subsequently underwent surgical re-section were retrospectively analyzed. The maximum standardized uptake value (SUVmax) was compared with patient age, sex, tumor location (gastrointestinal vs nongastrointestinal origin), tumor size, gross appearance, intratumoral cellularity, intratumoral infiltration of inflammatory cells, presence of peritumoral lymphoid cuffs, and expression status of glucose transporters 1 and 3 on tumor cells. RESULTS: The SUVmax of schwannomas ranged from 1.5 to 17.3 (median, 3.7). Significantly higher SUVmax was observed in gastrointestinal schwannomas (n = 4) compared with nongastrointestinal schwannomas (n = 18, p = 0.007) and in schwannomas with peritumoral lymphoid cuffs (n = 5) compared with those without peritumoral lymphoid cuffs (n = 17, p = 0.001). A significant correlation was seen between tumor location and the presence of peritumoral lymphoid cuffs (p < 0.001). Age, sex, tumor size, gross appearance, intratumoral cellularity, intratumoral inflammatory cell infiltration, and expression status of glucose transporters 1 and 3 on tumor cells had no significant correlation with SUVmax. CONCLUSION: Gastrointestinal schwannomas and schwannomas with peritumoral lymphoid cuffs may be associated with elevated FDG uptake. Knowledge of the features of schwannomas associated with increased uptake may be helpful to avoid misinterpretation of benign schwannomas as malignancy.

Influence of nonideal chirped fiber Bragg grating characteristics on all-optical clock recovery based on the temporal Talbot effect.

We theoretically and experimentally evaluate the influence of the bandwidth limitation and group delay ripple (GDR) of linearly chirped fiber Bragg gratings (LCFBGs) on the all-optical clock recovery utilizing the temporal Talbot effect. To simulate the reasonably arbitrary shape of the GDR of LCFBGs, the generalized distribution function model of GDR was proposed and utilized. The quality of recovered clock pulses was evaluated by using the proposed parameters "peak variation" and "pulse visibility." Simulation results indicated that both the signal pulses with < 1% duty factor and LCFBGs with the bandwidth of > approximately 125 times the bit rate, 10 nm for 10 Gbit/s input signal, were required to obtain both < approximately 20% peak variation and > approximately 17 dB pulse visibility of the clock pulses recovered from 2(7)-1 pseudorandom bit sequence (PRBS) pulses, and indicated that the LCFBGs with < approximately 20 ps peak-to-peak GDR could recover the clock pulses from the 10 Gbit/s signal with almost the same quality as that recovered with an ideal LCFBG (with no GDR). In addition, it was revealed that < approximately 20 ps peak-to-peak GDR did not degrade the timing jitter reduction effect. Qualitative agreement of the experimental and simulation results justified our analytical methods. Our analytical approach and results will be very useful to practically design the LCFBGs for an all-optical clock recovery circuit based on the temporal Talbot effect.

Postoperative gluteal skin damage associated with latent development of gluteal muscle damage.

Preceding this study, we observed two cases of concurrent postoperative gluteal skin and muscle damage with extremely high serum creatine kinase (CK) levels, both of which were unrelated to pressure-induced tissue injury. However, postoperative gluteal skin damage accompanied by gluteal muscle damage has not been previously reported and the association between gluteal skin damage, gluteal muscle damage and pressure-induced tissue injury has not previously been investigated. Therefore, we conducted this study to determine the postoperative incidence of gluteal skin damage associated with gluteal muscle damage and assess associations with postoperative serum CK levels and pressure-induced tissue injury. We prospectively evaluated postoperative incidence of gluteal skin damage and measured serum CK levels in 929 consecutive patients who underwent abdominal, urological or gynecological surgery at our hospital. Magnetic resonance imaging (MRI) of the pelvis was performed in 67 patients who consented. As a result, two of 929 patients developed postoperative gluteal skin damage accompanied by gluteal muscle damage. Gluteal muscle damage without gluteal skin damage was observed in 23 of the 67 patients who underwent MRI, and volumes of damaged gluteal muscle and postoperative serum CK levels were positively correlated. Both gluteal skin and muscle damage were distinguishable from pressure-induced tissue injury. Based on the results of this study, we could confirm the occurrence of postoperative gluteal skin damage, distinct from pressure sores, accompanied by gluteal muscle damage. We also revealed latent development of postoperative gluteal muscle damage, distinguishable from compression-induced tissue injury, without accompanying gluteal skin damage.