Role of IV iodinated contrast material in 18F-FDG PET/CT of liver metastases. AJR Am J Roentgenol. 2008;191:1436-1439. [PMID: 18941082 DOI: 10.2214/ajr.07.3750]

FDG PET and Split-Bolus Multi-Detector Row CT Fusion Imaging in Oncologic Patients: Preliminary Results

PURPOSE

To assess the incremental value of split-bolus multidetector computed tomography (CT) combined with fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for follow-up of oncologic patients.

MATERIALS AND METHODS

The institutional ethics committee approved the use of this protocol. Thirty-eight oncologic patients who underwent FDG PET/unenhanced multidetector CT and split-bolus multidetector CT for restaging were investigated retrospectively. The split-bolus CT protocol included imaging during the hepatic arterial and portal venous phases in one scan. Software was used for fusion of the independently acquired FDG PET and split-bolus CT data, and fused datasets were compared with FDG PET/unenhanced CT data. The standard of reference for diagnosis of lesions in all patients was a combination of histologic results (if available), clinical results (medical history, physical examination, and laboratory test results), and the results of follow-up imaging (conventional CT, magnetic resonance imaging, and/or ultrasonography) for at least 6 months. Descriptive statistics were used.

RESULTS

Fifty-nine true-positive lesions were identified with fused FDG PET/split-bolus CT; 41 were concordant and detected with both split-bolus CT and PET/unenhanced CT, 16 with split-bolus CT only, and two with PET/unenhanced CT. Two different false-positive lesions were identified with PET/unenhanced CT and PET/split-bolus CT. Furthermore, in 20 of 38 (53%) patients, FDG PET/split-bolus CT allowed detection of important additional findings (n = 40) not detected at FDG PET/unenhanced CT. Both the tumor-related findings (n = 13, 32.5%) and the non-tumor-related findings (n = 27, 67.5%) were important to the clinical treatment of these patients.

CONCLUSION

Fused FDG PET/split-bolus multidetector CT provides additional information compared with FDG PET/unenhanced multidetector CT in oncologic patients.

Non-invasive diagnostic imaging of colorectal liver metastases

Colorectal cancer is one of the few malignant tumors in which synchronous or metachronous liver metastases [colorectal liver metastases (CRLMs)] may be treated with surgery. It has been demonstrated that resection of CRLMs improves the long-term prognosis. On the other hand, patients with un-resectable CRLMs may benefit from chemotherapy alone or in addition to liver-directed therapies. The choice of the most appropriate therapeutic management of CRLMs depends mostly on the diagnostic imaging. Nowadays, multiple non-invasive imaging modalities are available and those have a pivotal role in the workup of patients with CRLMs. Although extensive research has been performed with regards to the diagnostic performance of ultrasonography, computed tomography, positron emission tomography and magnetic resonance for the detection of CRLMs, the optimal imaging strategies for staging and follow up are still to be established. This largely due to the progressive technological and pharmacological advances which are constantly improving the accuracy of each imaging modality. This review describes the non-invasive imaging approaches of CRLMs reporting the technical features, the clinical indications, the advantages and the potential limitations of each modality, as well as including some information on the development of new imaging modalities, the role of new contrast media and the feasibility of using parametric image analysis as diagnostic marker of presence of CRLMs.

Impact of concurrent diagnostic level CT with PET/CT on the utilization of stand-alone CT and MRI in the management of head and neck cancer patients

PURPOSE OF THE REPORT

This study aims to determine if the expansion of a PET/CT service to include simultaneous contrast-enhanced CT with PET (PET/DCT) leads to a reduction of supplemental diagnostic CT (sCT) performed within a 6-month period centered around PET/CT for initial treatment planning of patients with head and neck cancers.

PATIENTS AND METHODS

There were 91 patients with head and neck cancers who had a non-contrast-enhanced PET/CT with CT (PET/aCT), and 153 patients had a PET/DCT. We compared the utilization of sCT before and after PET/aCT or PET/DCT. Logistic regression analysis, unpaired t test, and analysis of variance were performed.

RESULTS

Among the 75 patients who had sCT scans in the 3 months before their PET/CT, 44 (58.7%) scans were performed in patients who had a PET/aCT and 31 (41.3%) scans were performed in patients who had a PET/DCT (P < 0.001). Among the 36 patients who had a CT in the 3 months after their baseline PET/CT, 23 (63.9%) were performed in patients who had a baseline PET/aCT and 13 (36.1%) were performed in patients who had a baseline PET/DCT (P < 0.001). The adjusted odds ratio for performing an sCT within 3 months before and after baseline PET/DCT scan as opposed to a PET/aCT scan was 0.24 (P < 0.001) and 0.31 (P < 0.01), respectively.

CONCLUSIONS

The opportunity to order simultaneous diagnostic CT imaging with PET/CT (PET/DCT) reduced the referrals for stand-alone CT neck imaging in the initial treatment plan of head and neck cancer patients when compared to a service that only offered the PET/CT scan with CT for attenuation correction (PET/aCT).

Optimizing the role of FDG PET-CT for potentially operable metastatic colorectal cancer

Recent treatment advances now allow a realistic chance of cure in selected patients with metastatic colorectal carcinoma (CRC). Accurate pre-treatment staging is crucial to ensure appropriate management by identification of patients with more advanced disease who will not benefit from surgery. (18)Fluorine 2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (PET-CT) has a firmly established role in staging, restaging, and recurrence detection of a range of tumors. This article will review the role of PET-CT in patients with CRC with a particular emphasis on optimizing the technique in patients with potentially operable metastatic disease.

Effect of lapatinib on hepatic parenchymal enhancement on gadoxetate disodium (EOB)-enhanced MRI scans of the rat liver

PURPOSE

The purpose of this study was to investigate the effect of lapatinib treatment on hepatic parenchymal enhancement on Gd-EOB-MRI scans in rat.

MATERIALS AND METHODS

Institutional animal review board approval was received prior to the commencement of all studies. Five rats received a single oral dose of 100 mg/kg/day lapatinib for 7 consecutive days. The controls (n = 5) were given 0.5 % (w/v) aqueous hydroxypropyl methyl cellulose containing 0.1 % (v/v) Tween 80 for 7 days. After the acquisition of gadoxetate disodium-enhanced MR images using 0.025 mmol gadolinium/kg, their livers were subjected to pathologic study to determine the expression level of organic anion-transporting polypeptide 1 (oatp1) and multi-drug resistance-associated protein 2 (mrp2).

RESULTS

Relative enhancement of the liver was similar in both groups. At the hepatobiliary phase, which in rats occurs 3 min after the injection of Gd-EOB, it was 0.90 ± 0.06 in lapatinib-treated rats and 0.84 ± 0.08 in the controls (p = 0.30). There was also no difference in the expression level of oatp1 and mrp2.

CONCLUSION

In rats, the administration of lapatinib for 7 days had no effect on hepatic parenchymal enhancement on Gd-EOB-MRI scans.

PET scan integration in lymphoma management

SUMMARY Despite a marked improvement in lymphoma treatment outcome, current prognostic models, relying on a pretreatment set of static clinical variables, appear unable to support a risk-adapted therapeutic strategy. On the other hand, functional imaging with 18F-fluoro-2-deoxy-D-glucose (FDG)-PET proved to be a reliable tool to dynamically assess tumor FDG uptake changes during and after treatment. In this article we aim to review the prognostic value of FDG-PET in all the stages of Hodgkin’s and non-Hodgkin’s lymphoma management, without the intent to address the diagnostic value of PET or to replace available consensus guidelines. In particular we focused on two critical issues: the cost–effectiveness of PET in the overall strategy of lymphoma diagnosis and treatment; and ongoing clinical trials adopting an interim PET-based strategy to modulate treatment intensity based on PET results. Finally, new trends in multimodality imaging, as well as in new radiopharmaceutical tracers, are briefly reviewed.

Selection for hepatic resection of colorectal liver metastases: expert consensus statement

Hepatic resection offers a chance of a cure in selected patients with colorectal liver metastases (CLM). To achieve adequate patient selection and curative surgery, (i) precise assessment of the extent of disease, (ii) sensitive criteria for chemotherapy effect, (iii) adequate decision making in surgical indication and (iv) an optimal surgical approach for pre-treated tumours are required. For assessment of the extent of the disease, contrast-enhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is recommended depending on the local expertise and availability. Positron emission tomography (PET) and PET/CT may offer additive information in detecting extrahepatic disease. The RECIST criteria are a reasonable method to evaluate the effect of chemotherapy. However, they are imperfect in predicting a pathological response in the era of modern systemic therapy with biological agents. The assessment of radiographical morphological changes is a better surrogate of the pathological response and survival especially in the patients treated with bevacizumab. Resectability of CLM is dependent on both anatomic and oncological factors. To decrease the surgical risk, a sufficient volume of liver remnant with adequate blood perfusion and biliary drainage is required according to the degree of histopathological injury of the underlying liver. Portal vein embolization is sometimes required to decrease the surgical risk in a patient with small future liver remnant volume. As a complete radiological response does not signify a complete pathological response, liver resection should include all the site of a tumour detected prior to systemic treatment.

Preoperative imaging for hepatic resection of colorectal cancer metastasis

Despite recent advances in chemotherapeutic agents, the prognosis for metastatic colon cancer remains poor. Over the past two decades, hepatic metastasectomy has emerged as a promising technique for improving survival in patients with metastatic colon cancer and in some cases providing long-term cure. To maximize safety and efficacy of metastasectomy, appropriate pre-operative imaging is needed. Advancements in computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) have led to improved detection of occult lesions and better definition of surgical anatomy. While CT, PET and MRI have a comparable sensitivity for detection of large liver metastases, MRI excels at detection of subcentimeter liver metastases compared to CT and FDG-PET, especially with the combination of diffusion weighted imaging (DWI) and hepatocyte-specific contrast agents. CT may be useful as a screening modality or in preoperative planning such as volumetric estimation of the remnant liver size or in defining preoperative arterial anatomy for hepatic artery infusion pump placement. While technologic advancements have led to unprecedented image quality and clarity, this does not replace the need for a dedicated, competent radiologist with experience in hepatic imaging.

Gadoxetate disodium-enhanced magnetic resonance imaging versus contrast-enhanced 18F-fluorodeoxyglucose positron emission tomography/computed tomography for the detection of colorectal liver metastases

PURPOSE

: To compare the diagnostic accuracy of gadoxetate disodium-enhanced magnetic resonance imaging (EOB-MRI) on a 3-T system and integrated contrast-enhanced F-fluorodeoxyglucose positron emission tomography/computed tomography (CE-PET/CT) for the detection of hepatic metastases from colorectal cancers.

MATERIALS AND METHODS

: The approval from the institutional review board was obtained, and the requirement for informed consent was waived. We retrospectively evaluated 135 metastases in 68 patients (37 men, 31 women; mean age: 68 years; age range: 37-82 years) who underwent both EOB-MRI and CE-PET/CT. A total of 103 metastases were confirmed during surgery and 32 were confirmed by imaging findings during follow-up. The images were independently reviewed by 2 observers. The diagnostic accuracies of EOB-MRI and CE-PET/CT were determined by calculating the areas under each reader-specific receiver operating characteristic curve (Az). Patient-based lesion sensitivity and specificity were compared using the McNemar test.

RESULTS

: The mean area under the Az on EOB-MRI versus CE-PET/CT was 0.94 versus 0.81 for all lesions (P < 0.001), 0.92 versus 0.60 for lesions ≤1 cm in size (P < 0.001), and 0.88 versus 0.96 for lesions >1 cm (P = 0.098), respectively. The sensitivity, specificity, positive predictive values, and negative predictive value on a patient basis were 100%, 71%, 97%, and 100% for EOB-MRI and 93%, 71%, 97%, and 57% for CE-PET/CT, respectively.

CONCLUSIONS

: EOB-MRI using a 3-T system is more accurate than CE-PET/CT, especially for the detection of small (≤1.0 cm) lesions. Patient-based analysis revealed that EOB-MRI has a higher sensitivity and negative predictive value than CE-PET/CT.

Clinical impact of FDG PET-CT in patients with potentially operable metastatic colorectal cancer

AIM

To assess the clinical impact of 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography-computed tomography (PET-CT) in patients with potentially resectable metastatic colorectal cancer.

MATERIALS AND METHODS

One hundred and two patients with potentially resectable metastatic colorectal cancer underwent FDG PET-CT in addition to conventional imaging over an 18-month period. The findings were compared to conventional imaging, with histological or clinico-radiological validation. The impact on subsequent management was evaluated using information from clinico-radiological databases.

RESULTS

Of 102 patients (mean age 67 years, range 27-85 years), 94 had liver, five had isolated lung, and three had limited peritoneal metastases. In 31 patients (30%) PET-CT had a major impact on subsequent management, by correctly clarifying indeterminate lesions on conventional imaging as inoperable metastatic disease in 16 patients, detecting previously unsuspected metastatic disease in nine patients, identifying occult second primary tumours in three patients, and correctly down-staging three patients. PET-CT had a minor impact in 12 patients (12%), no impact in 49 cases (48%), and a potentially negative impact in 10 cases (10%). Following PET-CT, 36 (35%) patients were no longer considered for surgery. Of those remaining operative 45 of 66 (68%) underwent potentially curative metastatic surgery. In this cohort PET-CT saved 16 futile laparotomies.

CONCLUSION

FDG PET-CT has a valuable role in selected patients with metastatic colorectal cancer by improving staging accuracy and characterizing indeterminate lesions and helps triage patients to the appropriate treatment.

Potential role of combined FDG PET/CT & contrast enhancement MRI in a rectal carcinoma model with nodal metastases characterized by a poor FDG-avidity

PURPOSE

To investigate the additional role of MRI contrast enhancement (CE) in the primary tumor and the FDG uptake at PET in the lymph-node metastases.

MATERIALS AND METHODS

A model of colorectal cancer induced by orthotopic HT-29 cells microinjection, producing pelvic lymph node metastases, was assessed using CE-MRI and FDG-PET. Histology and GLUT-1 immunohistochemistry were performed on primary tumors and iliac lymph nodes.

RESULTS

Primary tumors were characterized by low FDG-uptake but high CE-MRI, particularly at tumor periphery. Undetectable FDG-uptake characterized the metastatic lymph-nodes. Histology revealed large stromal bundles at tumor periphery and a dense network of stromal fibers and neoplastic cells in the inner portion of the tumors. Both primary tumors and positive lymph nodes showed poor GLUT-1 staining.

CONCLUSION

Our data support the complementary role of MRI-CE and FDG PET in some types of carcinomas characterized by abundant cancer-associated stroma and poor FDG avidity consequent to poor GLUT-1 transported. In these tumors FDG-PET alone may be not completely adequate to obtain an adequate tumor radiotherapy planning, and a combination with dual CE-MRI is strongly recommended.

Is contrast material needed after treatment of malignant lymphoma in positron emission tomography/computed tomography?

PURPOSE

Positron emission tomography (PET)/computed tomography (CT) with (18)F-fluorodeoxyglucose is widely used for post-therapeutic surveillance of malignant lymphoma. Debate still exists as to whether intravenous contrast media during the CT stage of a PET/CT scan should be used. The purpose of this study was to investigate the clinical value of contrast agent in PET/CT in patients with lymphoma following treatment.

PATIENTS AND METHODS

One hundred and twenty-two consecutive patients with malignant lymphoma underwent 146 PET/CT scans to monitor therapeutic response (n = 57) or surveillance during follow-up (n = 89). All patients had a conventional PET/CT scan with low-dose CT without contrast (ldCT), and then a full-dose CT scan with contrast (ceCT). Two datasets were interpreted separately and prevalence of discrepant results between the two methods was evaluated. In addition, differences of diagnostic performance were investigated for restaging.

RESULTS

Both PET + ldCT and PET + ceCT were positive in 22 cases and negative in 35 cases when monitoring response to therapy. There were no cases in which these techniques demonstrated inconsistent findings. For restaging, the patient-based sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET + ldCT were 70, 91, 76, 87, and 84%, respectively, and those of PET + ceCT were 74, 92, 81, 89, and 87%, respectively. Discrepant results between the two methods occurred in only 2 of 89 cases (2%).

CONCLUSION

PET/ceCT yielded more accurate findings than PET/ldCT in a limited number of cases. PET/ldCT may, therefore, be sufficient for routine PET/CT scanning for post-therapeutic assessment or restaging of lymphoma patients.

Use of computed tomography in the management of colorectal cancer

Computed tomography (CT) plays an important role in the management of colorectal cancer (CRC). The use of CT (colonography) as a screening tool for CRC has been validated and is expected to rise over time. The results of prior studies suggest that CT is suboptimal for assessment of local T stage and moderate for N stage disease. Recent advances in CT technology are expected to lead to some improvement in staging accuracy. At present, the main role of CT in pre-treatment imaging assessment lies in its use for the detection of distant metastases, especially in the liver. In a select group of patients, routine post-treatment surveillance with CT confers survival benefits. The role of CT for post-treatment assessment has been radically altered and improved with the advent of fusion positron emission tomography/CT. Perfusion CT shows promise as another functional imaging modality but further experience with this technique is necessary before it can be applied to routine clinical practice.

Fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FHLCC) generally occurs in young individuals lacking a background of chronic liver disease and other risk factors for hepatocellular carcinoma. The clinical presentations of FLHCC are generally nonspecific, and the alpha-fetoprotein level is typically within the normal range in most cases. Imaging studies have a major role in clinical diagnosis, but pathology is the gold standard in confirming diagnosis. Pathological characteristics of FLHCC include the presence of tumor cells with a deeply eosinophilic cytoplasm and macronucleoli surrounded by abundant fibrous bands. The most effective treatment for FLHCC is aggressive surgical resection. This comprehensive literature review gives a full account of the clinical, pathological, and molecular features of FLHCC.