Separate calculation of DW-MRI in assessing therapeutic effect in liver tumors in rats

AIM:To explore whether the antitumor effect of a vascular disrupting agent(VDA)would be enhanced by combining with an antiangiogenic agent,and whether such synergistic effects can be effectively evaluated with separate calculation of diffusion weighted magnetic resonance imaging(DW-MRI).METHODS:Thirty-seven rats with implanted liver tumors were randomized into the following three groups:(1)ZD6126,a kind of VDA;(2)ZDTHA,ZD6126 in combination with an antiangiogenic,thalidomide;and(3)control.Morphological DW-MRI were performed and quantified before,4 h and 2 d after treatment.The apparent diffusion coefficient(ADC)values were calculated separately for low b values(ADC low),high b values(ADC high)and all b values(ADC all).The tissue perfusion contribution,ADC perf,was calculated as ADC low-ADC high.Imaging findings were finally verified by histopathology.RESULTS:The combination therapy with ZDTHA significantly delayed tumor growth due to synergistic effects by inducing cumulative tumor necrosis.In addition to delaying tumor growth,ZDTHA caused tumor necrosis in an additive manner,which was verified by HE staining.Although both ADC high and ADC all in the ZD6126and ZDTHA groups were significantly higher compared to those in the control group on day 2,the entire tumor ADC high of ZDTHA was even higher than that of ZD6126,but the significant difference was not observed for ADCall between ZDTHA and ZD6126.This indicated that the perfusion insensitive ADC high values calculated from high b value images performed significantly better than ADC all for the monitoring of tumor necrosis on day 2.The perfusion sensitive ADC perf derived from ADC low by excluding high b value effects could better reflect the reduction of blood flow due to the vessel shutdown induced by ZD6126,compared to the ADC low at 4 h.The ADC perf could provide valuable perfusion information from DW-MRI data.CONCLUSION:The separate calculation of ADC is more useful than conventional averaged ADC in evaluating the efficacy of combination therapy with ZD6126and thalidomide for solid tumors.

Differential diagnosis of gallstones by using hypericin as a fluorescent optical imaging agent

AIM: To explore the feasibility of using hypericin as an optical imaging probe with affinity for cholesterol for differential fluorescent detection of human gallstones.METHODS: Cholesterol, mixed and pigment stones from cholecystectomy patients were incubated with hypericin or solvent. After 72 h, the stones were analysed for fluorescence(365 nm) and treated with 2-propanol/dimethyl sulfoxide for high performance liquid chromatography(HPLC) analysis. Rats with virtual gallbladder containing human cholesterol, mixed or pigment gallstones(VGHG) received 5 mg/kg hypericin or solvent and VGHG rats with cholesterol stones were given different hypericin doses(5-15 mg/kg). Twelve hours later, the stones were analysed at 365 nm. Biliary excretion and metabolites of hypericin were assessed in common bile duct(CBD) cannulated rats for 9 h using fluorospectrometry, HPLC and matrixassisted laser desorption/ionization-time-of-flight mass spectrometry(MALDI-TOF MS).RESULTS: Homogeneous high fluorescence was seen on cholesterol stones either pre-incubated with hypericin or extracted from VGHG rats receiving hypericin. Mixed stones showed a dotted fluorescent pattern, whereas pigment and solvent-treated ones lacked fluorescence. HPLC showed 7.68, 6.65 and 0.08 × 10^(-3) M of cholesterol in extracts from cholesterol, mixed, and pigment gallstones, respectively. Hypericin accounted for 2.0, 0.5 and 0.2 × 10-6 M in that order. On cholesterol stones from VGHG rats receiving different hypericin doses, a positive correlation was observed between dose and fluorescence. In the bile from CBD-cannulated rats, fluorescence represented 20% of the injected dose with two peaks in 9 h. HPLC analysis revealed that hypericin conjugates reached 60% of the peak area. By MALDI-TOF MS, hypericinglucuronide was detected. CONCLUSION: This study proves the potential use of hypericin for differential fluorescent detection of human gallstones regarding their chemical composition.

Intra-individual comparison of therapeutic responses to vascular disrupting agent CA4P between rodent primary and secondary liver cancers

AIM To compare therapeutic responses of a vascular-disrupting-agent, combretastatin-A4-phosphate(CA4 P), among hepatocellular carcinomas(HCCs) and implanted rhabdomyosarcoma(R1) in the same rats by magneticresonance-imaging(MRI), microangiography and histopathology.METHODS Thirty-six HCCs were created by diethylnitrosamine gavage in 14 rats that were also intrahepatically implanted with one R1 per rat as monitored by T2-/T1-weighted images(T2wI/T1wI) on a 3.0 T clinical MRIscanner. Vascular response and tumoral necrosis were detected by dynamic contrast-enhanced(DCE-) and CE-MRI before, 1 h after and 12 h after CA4P iv at 10 mg/kg(treatment group n = 7) or phosphate-buffered saline at 1.0 mL/kg(control group n = 7). Tumor blood supply was calculated by a semiquantitative DCE parameter of area under the time signal intensity curve(AUC30). In vivo MRI findings were verified by postmortem techniques.RESULTS On CE-T1wIs, unlike the negative response in all tumors of control animals, in treatment group CA4P caused rapid extensive vascular shutdown in all R1-tumors, but mildly or spottily in HCCs at 1 h. Consequently, tumor necrosis occurred massively in R1-tumors but patchily in HCCs at 12 h. AUC30 revealed vascular closure(66%) in R1-tumors at 1 h(P < 0.05), followed by further perfusion decrease at 12 h(P < 0.01), while less significant vascular clogging occurred in HCCs. Histomorphologically, CA4P induced more extensive necrosis in R1-tumors(92.6%) than in HCCs(50.2%)(P < 0.01); tumor vascularity heterogeneously scored +^+++ in HCCs but homogeneously scored ++ in R1-tumors.CONCLUSION This study suggests superior performance of CA4P in metastatic over primary liver cancers, which could guide future clinical applications of vascular-disruptingagents.