Detection Of Small Liver Metastases Research Articles

Respiratory gated and prolonged acquisition 18F-FDG PET improve preoperative assessment of colorectal liver metastases

Detection of small liver metastases from colorectal cancer by 18F-FDG PET/CT is hampered by high physiologic uptake in the liver parenchyma and respiratory movements during image acquisition. To investigate whether two tailored 18F-FDG PET liver acquisitions (prolonged liver acquisition time [PL-PET] and repeated breath-hold respiratory gated liver acquisition [RGL-PET]) would improve detection of colorectal liver metastases, when added to a standard whole body PET (WB-PET). Twenty consecutive patients referred to our hospital for surgical treatment of colorectal liver metastases diagnosed with contrast-enhanced CT underwent preoperative 18F-FDG PET/CT tailored for detection of liver metastases. Concordance between preoperative imaging results and true findings (histology and/or follow-up imaging) as well as changes in clinical management, based on 18F-FDG PET/CT findings, were documented. Background noise, defined as the standard deviation measured in a reference region within the normal liver parenchyma, was compared between the three 18F-FDG PET/CT protocols. WB-PET, PL-PET, and RGL-PET showed suspicious liver lesions in 18 out of 20 patients. Compared to WB-PET alone, the combination of PL-PET and RGL-PET showed additional lesions in the liver in seven out of the 18 patients. The combination of all three PET acquisitions changed clinical management in four patients. Two patients with negative PET results were later found to have benign liver lesions. The addition of tailored liver-specific 18F-FDG PET/CT protocols (PL-PET and RGL-PET) to a WB-PET, improved the detection of intrahepatic colorectal metastases, compared to WB-PET alone. Such add-ons can change clinical patient management of potentially resectable colorectal liver metastases.

Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications.

The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions. The main indications for the method include: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up.

Comparison of monopolar and bipolar diffusion weighted imaging sequences for detection of small hepatic metastases

ObjectiveTo compare monopolar (MP) and bipolar (BP) diffusion weighted imaging (DWI) in detecting small liver metastases. Materials and methodsEighty-eight patients underwent 3-T MRI. The signal-to-noise ratios (SNR) of the liver parenchyma and lesions, the lesion-to-liver contrast-to-noise ratios (CNR), and the detection sensitivities were compared. The lesion distortion was scored (LDS) from 4 (no distortion) to 1 (excessive distortion), dichotomised as no-distortion and distortion, and the association between detected lesions for each reader in the MP or BP DWI group and the dichotomised lesion distortion degree was assessed. ResultForty-six hepatic metastases were confirmed. The CNR with BP images showed significantly higher values than with MP (P=0.017). The detection sensitivities of the three readers were higher in the BP sequence than in MP, and one reader detected significantly more hepatic lesions with BP images (P=0.04). LDS was significantly improved with BP sequence (P=0.002). In the no-distortion group, excluding the MP DWI assessments of one reader, detection sensitivities were significantly higher than in the distortion group (P<0.001 and P=0.002, respectively). ConclusionReduced lesion distortion improves the detection of small liver metastases, and BP is more sensitive in detecting small liver metastases than MP DWI.

Detection of liver metastases using a high spatial resolution ultrasound contrast mode: Detection of small liver metastases in different primary malignancies

Detection of liver metastases using a high spatial resolution ultrasound contrast mode: Detection of small liver metastases in different primary malignancies

Improved Visualization of Vessels and Hepatic Tumors by Micro-Computed Tomography (CT) Using Iodinated Liposomes

The goal of this study was to determine whether iodinated liposomes are a suitable tracer for mice microvessel and liver imaging by preclinical computed tomography (CT). Iodinated liposomes were evaluated for vessel and liver imaging. A first group of nude mice was imaged by micro-CT after i.v. injection of liposomes at 1 or 2 gI/kg body weight (b.w.) for intervals up to 24 hours. A second group of mice bearing liver micrometastases was imaged after injection of liposomes at 2 gI/kg b.w. for intervals up to 24 hours. Vascular enhancements of 120 +/- 8 and 322 +/- 20 Hounsfield unit (HU) were obtained after injection of liposomes at 1 or 2 gI/kg b.w., respectively. This enhancement decreased with a blood half-life of 135 +/- 10 and 86 +/- 9 minutes, respectively. Liver enhancement of 157 +/- 5 and 235 +/- 23 HU were obtained after injection of iodinated liposomes at 1 and 2 gI/kg b.w., respectively. Liver micrometastases (250 microm) were detectable after injection of iodinated liposomes at 2 gI/kg b.w. Iodinated liposomes are a suitable contrast agent for vessels and liver imaging by micro-CT allowing clear vascular enhancement and detection of small liver metastases.

Prospective, Blinded Comparison of Helical CT and CT Arterial Portography in the Assessment of Hepatic Metastasis from Colorectal Carcinoma

This prospective blinded comparison of helical CT and helical CT arterial portography aimed to detect liver metastasis from colorectal carcinoma. 50 patients with colorectal carcinoma were evaluated comparing helical CT with helical CT arterial portography. Each imaging study was evaluated on a 5-point ROC scale by radiologists blinded to the other imaging findings, and the results were compared, with the surgical and pathologic findings as the gold standard. Of the 127 lesions found at pathology identified as metastatic colorectal cancer, helical CT correctly identified 85 (69%) and CT portography 96 (76%). When subgroups with lesions <3 cm (48 patients) and patients with maximum tumor size <3 cm (18 patients) were considered, CT portography was always better than helical CT in terms of sensitivity, specificity, positive predictive value, and negative predictive value. ROC analysis adjusting for multiple lesions per patient revealed significantly greater area under the curve (AUC) for the subgroup of lesions <3 cm (CT-AUC of 77% and CT portography AUC of 81%; P = 0.002). For identification of large metastases, helical CT and CT portography have similar yield. However, for detection of small liver metastases, CT portography remains superior for lesion detectability.

Comparison of CT During Arterial Portography and MR During Arterial Portography in the Detection of Liver Metastases

This study compared MR during arterial portography (MRAP) with CT during arterial portography (CTAP) with regard to the detection and differentiation of liver metastases before surgery. Fifteen patients with liver metastases were enrolled before surgery according to the guidelines of our institutional review board and good clinical practice. After mesentericography, unenhanced scans (Volume Zoom) were performed initially. For CTAP, the contrast medium was injected through the superior mesenteric artery. Images were acquired in portal and delayed enhancement. The MR protocol (1.5 T; Magnetom Symphony) started with T1-weighted fast low-angle shot (FLASH) T2-weighted turbo spin echo (TSE). MRAP followed with gadolinium-enhanced dynamic T1-weighted 3D FLASH. Delayed-phase T1-weighted 2D FLASH axial images were performed 2 min after IV injection of the contrast medium. Qualitative and quantitative evaluation of CTAP and MRAP was performed by three blinded radiologists regarding the number of lesions and their size, localization, and differential diagnosis. The overall sensitivity in detecting liver metastases was 97% with MRAP and 93% with CTAP (p > 0.05, not significant [n.s.]). The specificity was calculated to be 97% for MRAP and 82% for CTAP (p < 0.0001, statistically significant [s.s.]). The differences in sensitivity were more accentuated if only lesions 10 mm or smaller were considered (95% vs 88%, p > 0.05, n.s.), for which the respective specificities were 95% and 80% (p < 0.0014, s.s.). Improvements in sensitivity and specificity were associated with a higher lesion-to-liver contrast-to-noise ratio (59.4 +/- 51.0 for MRAP vs 10.4 +/- 7.3 for CTAP) and resulted in higher diagnostic confidence in the differential diagnosis of liver lesions (p < 0.001, s.s.) and better interobserver agreement (median kappa value, 0.88 vs 0.63). MRAP proved to be a reliable method in the preoperative detection of small liver metastases in particular, with a higher sensitivity and specificity than CTAP. If organizational difficulties of MRAP can be overcome, MRAP could be considered instead of CTAP in the preoperative invasive evaluation of metastatic liver disease.

The value of colour duplex sonography in the assessment of surgical resectability of pancreatic tumors

The Value of Colour Duplex Sonography in the Assessment of Surgical Resectability of Pancreatic Tumors. The aim of this study was to evaluate the assessment by modern colour duplex imaging (CDI) concerning the relation between tumour and vessels including haemodynamic parameters in the main abdominal arteries and the portal system, and to evaluate the influence of these results on surgical decision making. From January 1997 to October 1998, 146 patients with a tumour of the pancreas were included in a prospective study. Tumour contact to vessels and to the retroperitoneum, data on the flow in the main abdominal arteries and the portal circulation (regional topography) as well as the detection of liver metastases, enlarged lymph nodes and peritoneal carcinomatosis were defined as representing criteria of resectability. The results were compared with the intraoperative situation and with the definite histological findings. In 57 resectable tumours, the portal system was found to be infiltrated by the tumour up to a length of 1.5 cm. The flow velocity reached between 4 and 53 cm/s (mean flow) and 9 to 105 cm/s (maximum flow). Out of 146 pancreatic tumours, 89 were found as being non-resectable. In these cases, the measured parameters differed depending on the degree of tumour infiltration in to the portal circulation. We measured values from 0 to 96 cm/s (mean flow) and from 0 to 201 cm/s (maximum flow) with loss of breath-dependent modulation. The contact area between tumor and portal vessel was longer than 2 cm. Pathological flow in the main abdominal arteries was only found in 2 of 13 cases. The local situation was assessed correctly in 140 out of 146 cases by CDI (sensitivity of 93.0 %, specificity of 97.8 %, positive predictive value of 96.4 %, negative predictive value of 95.6 %). Regarding the complete oncological status (local situation, metastases, lymph node involvement and peritoneal carcinomatosis), a sensitivity of 82.5 % and a specificity of 92.1 % (positive predictive value of 87.0 %, negative predictive value of 89.1 %) was found. Modern CDI can reliably assess the resectability of pancreatic tumours by the evaluation of morphological and haemodynamic parameters. There are still difficulties in the assessment of lymph node involvement as well as in the detection of small liver metastases and of peritoneal carcinomatosis without ascites.

Carcinoembryonic antigen expression, antibody localisation and immunophotodetection of human colon cancer liver metastases in nude mice: a model for radioimmunotherapy.

Colorectal cancer frequently disseminates through the portal vein into the liver. In this study, outbred Swiss nude mice were adapted to facilitate the induction of liver metastases by a pre-grafting treatment with 6 Gy total body irradiation and i.v. injection of anti-asialo GM1 antibody. One day later, cultured LS 174T human colon cancer cells were injected into the surgically exposed spleen, which was resected 3 min later. In 48 of 65 mice, a few to several hundred liver metastases were macroscopically observed at dissection 3 to 4 weeks after transplantation. Ten of 10 mice, followed-up for survival, died with multiple large confluent liver metastases. By reducing the radiation dose to 4 or 0 Gy, or omitting the anti-asialo GM1 antibody injection, only 60%, 37% or 50% of mice, respectively, had visible metastases 3 weeks after transplantation. Carcinoembryonic antigen (CEA) measured in tumour extracts was in the mean 25.6 micrograms/g in liver metastases compared with 9.2 micrograms/g in s.c. tumours. Uptake of radiolabelled anti-CEA monoclonal antibody (MAb) in the metastases 12, 24 and 48 hr after injection gave a mean value of 39% of the injected dose per gram of tissue (ID/g). In comparison, MAb uptake in s.c. and intrasplenic tumours or lung metastases gave a mean percentage ID/g of 20, 18 and 15, respectively. Laser-induced fluorescence after injection of indocyanin-MAb conjugate allowed direct visual detection of small liver metastases, including some that were not visible under normal light. Preliminary results showed that mice, pre-treated with 4 Gy irradiation and the anti-asialo GM1 injection, were tolerant to radioimmunotherapy with a total dose of 500 muCi 131I labeled anti-CEA intact MAbs given in 3 injections.

Intraoperative ultrasound in colorectal cancer patients undergoing apparently curative surgery: Correlation with two year follow-up

Conventional ultrasound (US) and computerized tomography (CT) are well recognized to be limited in the detection of small liver metastases. In this study, we assessed the use of intraoperative ultrasound (IOUS) in the detection of 'occult' liver metastases in colorectal cancer patients undergoing apparently curative surgery of the primary colonic carcinoma. Ninety three colorectal cancer patients undergoing apparently curative surgery on the basis of preoperative US, CT and laparotomy were studied. All patients underwent IOUS examination of the liver. After two year follow-up, 27 of these 93 patients developed overt liver metastases and of these 27, only five had been detected by IOUS examinations at the time of laparotomy. The results suggest that IOUS is relatively insensitive in the detection of occult colorectal liver metastases. Its routine use as a screening tool during primary surgery is therefore not recommended.

Image-directed Doppler ultrasonography: a novel technique for the diagnosis of colorectal liver metastases.

Image-directed Doppler ultrasonography has been used to measure changes in hepatic arterial and portal venous blood flows in 22 controls and 88 patients with colorectal cancer. Doppler Perfusion Index, (DPI, ratio of hepatic arterial to total liver blood flow) and Doppler Flow Ratio (DFR, ratio of hepatic arterial to portal venous blood flow) of controls and patients with overt liver metastases were clearly separated (p < 0.0001). There was a significant reduction in the Hepatic Arterial Resistive Index (HARI) of patients with overt liver metastases (p < 0.0001). Percentage Hepatic Replacement (PHR) by metastases, measured using a computed tomography scanner, did not correlate with DFR or DPI. The results suggest that the measurement of hepatic perfusion changes using image-directed Doppler ultrasonography may be of value in the detection of small liver metastases.