FDG-PET-CT and whole-body MRI for triage in patients planned for radioembolisation therapy

Purpose

The purpose was to evaluate the potential of FDG–PET–CT and whole-body MRI (WB-MRI) as diagnostic triage methods for patients planned for radioembolisation of metastatic liver disease.

Materials and methods

135 patients with multifocal liver metastases were evaluated for potential palliative therapy with radioembolisation using 90-Yttrium microspheres. All patients were examined consecutively with FDG–PET–CT and WB-MRI for exclusion of relevant extra-hepatic tumor manifestations. All patients underwent 99mTc-albumine angiography followed by scintigraphy to exclude significant hepato-pulmonary shunting.

Results

Out of the 135 patients included into the pre-therapeutic diagnostic algorithm, 56% were eligible and received radioembolisation, while 44% could not be treated. In 91% the exclusion criteria was diagnosis of significant extra-hepatic metastatic disease. In 85% exclusion diagnosis was made concordantly by both FDG–PET–CT and WB-MRI, in 9% diagnosis was provided by PET–CT, in 6% by WB-MRI alone. Patient-based sensitivity for detection of extra-hepatic disease was 94% for PET–CT and 91% for WB-MRI. False-positive diagnosis of extrahepatic disease leading to exclusion for radioembolisation therapy was made in 2% of patients, in one patient by PET–CT and in one patient by WB-MRI alone. Overall, specificity for inclusion of radioembolisation therapy by combining both modalities was 99%. In 9% of patients angiographic diagnosis made radioembolisation impossible, in 7% solely the angiographic findings were decisive.

Conclusion

Both FDG–PET–CT and WB-MRI are efficient diagnostic triage methods for patients planned for radioembolisation of liver metastases. Overall, FDG–PET–CT shows a trend to higher diagnostic accuracy compared to WB-MRI and may be used as imaging method of choice as a standalone examination. In combination, both modalities exhibited high sensitivity for the diagnosis of extra-hepatic tumor manifestations and result in high specificity.     

Detection and characterization of liver metastases: 16--slice multidetector computed tomography versus superparamagnetic iron oxide-enhanced magnetic resonance imaging

The aim of our study was to compare the diagnostic performance of 16--slice multidetector computed tomography with that of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the detection of small hepatic metastases and in the differentiation of hepatic metastases from cysts. Twenty-three patients with 55 liver metastases and 14 liver cysts underwent SPIO-enhanced MR imaging and multiphasic CT using 16-MDCT. Two observers independently analyzed each image, in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation as metastases or cysts for MDCT and SPIO-enhanced MR imaging were calculated using receiver operating characteristic analysis. For all observers, the Az values of SPIO-enhanced MR imaging for lesion detection and differentiation of liver metastases from cysts (mean 0.955, 0.999) were higher than those of MDCT (mean 0.925, 0.982), but not statistically significantly so (P>0.05). Sensitivity of SPIO-enhanced MR imaging with regard to the detection of liver metastases (mean 94.5%) was significantly higher than that of MDCT (mean 80.0%) (P<0.05). SPIO-enhanced MR imaging and 16-MDCT showed similar diagnostic accuracies for detection and differentiation of liver metastases from cysts, but sensitivity of SPIO-enhanced imaging in the detection of liver metastases was superior to that of 16-MDCT.     

Comparison of contrast-enhanced ultrasonography versus baseline ultrasound and contrast-enhanced computed tomography in metastatic disease of the liver: diagnostic performance and confidence

Aim: The aim of this study was to compare contrast-enhanced ultrasonography (CEUS) to baseline US and contrast-enhanced computed tomography (CT) in metastatic disease of the liver diagnosed or suspected by US during presurgical staging or postsurgical follow-up for primary malignancies. Materials and methods: Two hundred-fifty-three patients considered suitable for US due to the complete explorability of the liver and with one to five proven or suspected liver metastases at baseline US were included. All patients underwent US before and after microbubble injection, and multiphase contrast-enhanced CT. Independent panels of readers reviewed US and CT scans and recorded liver metastases according to a 5-grade scale of diagnostic confidence. Sensitivity, specificity (diagnostic performance) and area under the receiver operating characteristics (ROC) curve (diagnostic confidence) were calculated. Results: Reference standards revealed no metastases in 57/253, more than five in 59/253, and one to five in 137/253 patients. In patients with one to five metastases, CEUS versus baseline US revealed more metastases in 64/137 and the same number in 73/137 patients while CEUS versus CT revealed more metastases in 10/137, the same number in 99/137, and lower number in 28/137. Sensitivity, specificity, and area under ROC curve of CEUS (83%, 84%, 0.929, respectively) differed from baseline US (40%, 63%, 0.579, respectively; P<0.01) while did not differ from CT (89%, 89%, 0.945, respectively; P>0.05). Conclusion: CEUS improved liver metastases diagnosis in comparison with baseline US while it revealed similar diagnostic performance and confidence to contrast-enhanced CT in patients considered suitable for US and with proven or suspected liver metastases at baseline US.     

Accuracy and confidence of Gd-EOB-DTPA enhanced MRI and diffusion-weighted imaging alone and in combination for the diagnosis of liver metastases

Purpose

To evaluate the accuracy and confidence in diagnosing liver metastases using combined gadolinium-EOB-DTPA (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI)/diffusion-weighted imaging (DWI) in comparison to Gd-EOB-DTPA enhanced MRI and DWI alone.

Materials and methods

Forty-three patients (age, 58 ± 13 years) with 89 liver lesions (28 benign, 61 malignant) underwent liver MRI for suspected liver metastases. Three image sets (DWI, Gd-EOB-DTPA and combined Gd-EOB-DTPA/DWI) in combination with unenhanced T1- and T2-weighted images were reviewed by three readers. Detection rates of focal liver lesions were assessed and diagnostic accuracy was evaluated by calculating the areas under the receiver-operating-characteristics curve (AUC). Confidence in diagnosis was evaluated on a 3-point scale. Histopathology and imaging follow-up served as the standard of reference.

Results

Detection of liver lesions and confidence in final diagnosis for all readers were significantly higher for the combined Gd-EOB-DTPA/DWI dataset than for DWI. The combination of DWI and Gd-EOB-DTPA rendered a significantly higher confidence in final diagnosis (2.44 vs. 2.50) than Gd-EOB-DTPA alone for one reader. For two readers, accuracy in diagnosis of liver metastases was significantly higher for Gd-EOB-DTPA/DWI (AUCs of 0.84 and 0.83) than for DWI datasets (AUCs of 0.73 and 0.72). Adding DWI to Gd-EOB-DTPA did not significantly increase diagnostic accuracy as compared to Gd-EOB-DTPA imaging alone.

Conclusion

Addition of DWI sequences to Gd-EOB-DTPA enhanced MRI did not significantly increase diagnostic accuracy as compared to Gd-EOB-DTPA enhanced MRI alone in the diagnosis of liver metastases. However, the increase in diagnostic confidence might justify acquisition of DWI sequences in a dedicated MRI protocol.     

Detection of liver metastases: gadobenate dimeglumine-enhanced three-dimensional dynamic phases and one-hour delayed phase MR imaging versus superparamagnetic iron oxide-enhanced MR imaging

The aim of this study was to compare the diagnostic performance of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging, including dynamic phases and one-hour delayed phase, versus superparamagnetic iron oxide (SPIO)-enhanced imaging for detection of liver metastases. Twenty-three patients with 59 liver metastases underwent Gd-BOPTA-enhanced MR imaging (unenhanced, arterial, portal, equilibrium and one-hour delayed phase) using three-dimensional volumetric interpolated imaging and SPIO-enhanced T2-weighted turbo spin–echo and T2*-weighted gradient-echo sequences on a 1.5-T unit. Three observers independently interpreted the three sets of images, i.e. Gd-BOPTA-enhanced dynamic MRI (set 1), delayed phase imaging (set 2) and SPIO-enhanced MRI (set 3). Diagnostic accuracy was evaluated using the alternative-free response receiver operating chracteristic (ROC) analysis. Sensitivity and positive predictive value were also evaluated. The mean accuracy (Az values) and sensitivity of Gd-BOPTA-enhanced delayed phase imaging (0.982, 95.5%) were comparable to those of SPIO-enhanced imaging (0.984, 97.2%). In addition, Az values and sensitivities of both imaging sets were significantly higher than those of Gd-BOPTA-enhanced dynamic images (0.826, 77.4%: p<0.05). There was no significant difference in the positive predictive value among the three image sets. Gd-BOPTA-enhanced delayed phase imaging showed comparable diagnostic performance to SPIO-enhanced imaging for the detection of liver metastases, and had a better diagnostic performance than Gd-BOPTA-enhanced dynamic images.     

Evaluation of radiological prognostic factors of hepatic metastases in patients with non-functional pancreatic neuroendocrine tumors

Purpose

There are different therapeutic options in non-functional well to moderately differentiated (G1 and G2) pancreatic neuroendocrine tumors (pNET) with unresectable hepatic metastases including systemic chemotherapy and novel molecular targeted therapies. Treatment with somatostatin analogs (SSA) as antiproliferative agents is optional. At initial diagnosis watchful waiting until tumor progression is a well-established approach. Goal of this study was to evaluate imaging features as potential prognostic factors predicting early tumor progression in order to select patients that might benefit from an earlier initiation of medical treatment.

Patients and methods

In 44 patients we correlated tumor grade, chromogranin A (CgA) levels, treatment with SSA and imaging features of hepatic metastases on contrast-enhanced multiphase CT and MR imaging with time to tumor progression (TTP) according to RECIST 1.0.

Results

In the total patient cohort none of the tested imaging features was found to be a statistically significant prognostic factor for TTP. Since treatment with SSA was associated with an increased TTP we also analyzed a subgroup of 30 patients not treated with SSA. In this subgroup of patients hypoenhancement of hepatic metastases during early contrast phases was found to be a negative prognostic factor for early tumor progression within 12 months (p = 0.039). The other evaluated parameters including hepatic tumor load, number of metastases, and presence of regressive morphological changes did not reveal significant results.

Conclusion

Hypovascularization of liver metastases from G1 and G2 pNET reflected by hypoenhancement during the early contrast phases seems to be associated with early tumor progression. In patients with hypoenhancing metastases repeated biopsy for reassessment of grading of these metastases, and early initiation of therapy should be considered.     

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.     

Quantitative dynamic contrast-enhanced sonography of hepatic tumors

Liver tumors are defined using quantitative dynamic contrast-enhanced ultrasound compared to histological diagnosis, respectively, long-term follow-ups. Forty-two focal liver lesions in 39 patients were examined by contrast harmonic imaging over a period of 2 min after bolus injection of 10-ml galactose-based contrast agent. Vascular enhancement was quantified by using a dedicated software that allowed us to place representative regions of interest (ROI) in the center of the lesion, in the complete lesion, in regular liver parenchyma and in representative liver vessels (artery, vein and portal vein). Peak enhancement was judged to be either in the arterial, portal venous or in the late phase of liver perfusion. The lesion was described as hypovascular, isovascular and hypervascular compared to liver parenchyma. Contrast uptake was described as centrifugal or centripetal and peripheral or homogenous, respectively. Characterization of the lesions was performed unenhanced and after contrast by four independent specialists unaware of histology. Diagnosis of malignancy was evaluated by using a receiver operating characteristic (ROC) analysis, also overall accuracy, average sensitivity, specificity and negative and positive predictive values were calculated. Interobserver agreement was defined by the Kappa statistics. Histologic examination revealed 29 malignant [hepatocellular carcinoma (HCC), n=11; cholangiocellular carcinoma (CCC), n=1; lymphoma, n=1; metastases, n=16)] and 7 benign [hemangioma, n=1; focal nodular hyperplasia (FNH), n=4, adenoma, n=2)] lesions. Six benign lesions (hemangioma n=1; FNH n=5) were proved by long-term follow-up. ROC analysis regarding the diagnosis of malignancy showed values from 0.43 to 0.62 (mean 0.57) before and from 0.70 to 0.80 (mean 0.75) after contrast agent, respectively. The average values for sensitivity, specificity, accuracy and negative and positive predictive values were 66, 26, 62, 45 and 73% unenhanced and 83, 49, 73, 65 and 82% after contrast, respectively. The interobserver agreement was 0.54 and 0.65 for unenhanced and enhanced examinations, respectively. Quantitative dynamic contrast-enhanced sonography improves the diagnosis of malignancy in liver lesions.     

Hepatic Arterial Embolization and Chemoembolization in the Management of Patients with Large-Volume Liver Metastases

The purpose of this study was to assess the role of hepatic arterial embolization (HAE) and chemoembolization (HACE) in patients with large-volume liver metastases. Patients with metastatic neuroendocrine tumors, melanomas, or gastrointestinal stromal tumors (GISTs) with >75% liver involvement who underwent HAE or HACE were included in the study. Radiologic response, progression-free survival (PFS), overall survival (OS), and postprocedure complications were assessed. Sixty patients underwent 123 treatment sessions. Of the 48 patients for whom follow-up imaging was available, partial response was seen in 12 (25%) patients, minimal response in 6 (12%), stable disease in 22 (46%), and progressive disease in 8 (17%). Median OS and PFS were 9.3 and 4.9 months, respectively. Treatment resulted in radiologic response or disease stabilization in 82% and symptomatic response in 65% of patients with neuroendocrine tumors. Patients with neuroendocrine tumors had higher response rates (44% vs. 27% and 0%; p = 0.31) and longer PFS (9.2 vs. 2.0 and 2.3 months; p < 0.0001) and OS (17.9 vs. 2.4 and 2.3 months; p < 0.0001) compared to patients with melanomas and GISTs. Major complications occurred in 21 patients after 23 (19%) of the 123 sessions. Nine of the 12 patients who developed major complications resulting in death had additional risk factors—carcinoid heart disease, sepsis, rapidly worsening performance status, or anasarca. In conclusion, in patients with neuroendocrine tumors with >75% liver involvement, HAE/HACE resulted in symptom palliation and radiologic response or disease stabilization in the majority of patients. Patients with hepatic metastases from melanomas and GISTs, however, did not show any appreciable benefit from this procedure. Patients with massive liver tumor burden, who have additional risk factors, should not be subjected to HAE/HACE because of the high risk of procedure-related mortality.     

Recomendaciones de expertos sobre el uso de ácido gadoxético en pacientes con metástasis hepáticas en España

Background and aimsMagnetic resonance imaging (MRI) with gadoxetic acid is widely used in clinical practice in Spain for the diagnosis, treatment, and follow-up of patients with liver metastases, although its use varies. This paper aims to provide recommendations for the use of MRI with gadoxetic acid in the detection and diagnosis of liver metastases in clinical practice in Spain.Material and methodsThis project was undertaken by a group of nine experts who analyzed a series of recommendations about the use of gadoxetic acid extracted from international consensus documents. From this analysis, the experts decided to reject, adopt, contextualize, or adapt each of the recommendations. Once established, the final recommendations were voted on by the same group of experts.ResultsThe experts reached a consensus about five recommendations related to the use of this imaging technique in the management of liver metastases in three clinical situations: (i) in the detection, (ii) in the diagnosis and preoperative characterization, and (iii) in the detection after a chemotherapy treatment.ConclusionThe results support a clinical benefit for MRI with gadoxetic acid in the detection of liver metastases, favoring preoperative planning, especially in metastases measuring less than 1 cm, thus facilitating early diagnosis of metastatic spread.     

Benign liver lesions: implications of detection in cancer patients

A review of liver sonograms obtained for cancer patients (excluding primary liver cancers) over a 12 year period found 829 benign lesions: non-parasitic cysts (427 cases), hemangiomas (216 cases), solitary calcifications (79 cases), focal fatty infiltration (62 cases), and miscellaneous lesions (45 cases). These benign pathologies represented 41.8% of the focal hepatic lesions observed during this period in this population; hepatic metastases accounted for the remaining 58.2%. Marked female predilection was noted for the nonparasitic cysts, hemangiomas, and focal fatty infiltration; 63–78.7% of these lesions were solitary, and first-line imaging by US was sufficient for diagnosis of 66.1–98.2% of cases. Analysis of lesion evolution over more than 5 years revealed modifications in 17% of hemangiomas, 23.9% of nonparasitic cysts, and 75% of cases of focal fatty infiltration. Systematic pretherapy liver sonography can be proposed owing to the high frequency of benign liver lesions that can create diagnostic problems during follow-up of cancer patients. Correspondence to: J. N. Bruneton     

Magnetic resonance imaging of the liver: New imaging strategies for evaluating focal liver lesions

The early detection of focal liver lesions, particularly those which are malignant, is of utmost importance. The resection of liver metastases of some malignancies (including colorectal cancer) has been shown to improve the survival of patients. Exact knowledge of the number, size, and regional distribution of liver metastases is essential to determine their resectability. Almost all focal liver lesions larger than 10 mm are demonstrated with current imaging techniques but the detection of smaller focal liver lesions is still relatively poor. One of the advantages of magnetic resonance imaging (MRI) of the liver is better soft tissue contrast (compared to other radiologic modalities), which allows better detection and characterization of the focal liver lesions in question. Developments in MRI hardware and software and the availability of novel MRI contrast agents have further improved the diagnostic yield of MRI in lesion detection and characterization. Although the primary modalities for liver imaging are ultrasound and computed tomography, recent studies have suggested that MRI is the most sensitive method for detecting small liver metastatic lesions, and MRI is now considered the pre-operative standard method for diagnosis. Two recent developments in MRI sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and keyhole-based dynamic contrast-enhanced (DCE) MRI (4D THRIVE). DWI allows improved detection (b = 10 s/mm(2)) of small (< 10 mm) focal liver lesions in particular, and is useful as a road map sequence. Also, using higher b-values, the calculation of the apparent diffusion coefficient value, true diffusion coefficient, D, and the perfusion fraction, f, has been used for the characterization of focal liver lesions. DCE 4D THRIVE enables MRI of the liver with high temporal and spatial resolution and full liver coverage. 4D THRIVE improves evaluation of focal liver lesions, providing multiple arterial and venous phases, and allows the calculation of perfusion parameters using pharmacokinetic models. 4D THRIVE has potential benefits in terms of detection, characterization and staging of focal liver lesions and in monitoring therapy.     

Prospective study of chemoembolization (CE) of liver metastases from endocrine tumors. A report of 15 cases

Fifteen patients with unresectable liver metastases of endocrine tumors (nine carcinoid tumors and six gastrinomas) were treated with an intraarterial emulsion of iodized oil and adriamycin followed by gelatin sponge particles. Therapeutic efficacy was evaluated in terms of hormone levels and tumor size as measured with computed tomography. Six patients showed a reduction in tumor size, and 4 a response in tumor marker levels. All these metastases were derived from primary carcinoid. All cancer-related syndromes disappeared. There were two major complications. The response in these 6 patients lasted from 2 to 39 months. Metastasis from primary gastrinomas did not respond to CE. These results indicate that chemoembolization is useful palliative therapy for patients with hormone-secreting tumors of the liver, particularly in carcinoids Correspondence to: P. Legmann     

Technetium-99m DISIDA hepatobiliary tract imaging in pseudotumors of the liver

Tc-99m sulfur colloid images of the liver are frequently falsely reported as tumor or metastases in certain space occupying lesions of the liver. Whether a primary malignancy is known or not, every suspicious space-occupying lesion of the liver should be given the benefit of alternate diagnostic studies before a firm diagnosis of neoplasia is made. This is critical when the decision regarding chemotherapy has to be made. Timely intervention by other diagnostic modalities may obviate the consideration of chemotherapy in cases where there are no liver metastases. The case presented below illustrates the value of hepatobiliary tract imaging in pseudotumors of the liver.     

Bildgebende Diagnostik der Leberzirrhose

For the diagnosis of liver cirrhosis ultrasound, computed tomography, magnetic resonance imaging, and angiography are recommended as imaging modalities. Ultrasound of the liver is used as a screening imaging tool in cases of patients suspicious for diffuse liver disease and is helpful in the term of follow-up examinations. Computed tomography is mainly performed to clarify the presence of liver disease detected by ultrasound. In this context, accurate examination of the vascular structures of the liver as well as extrahepatic situation, is of the essence. Diagnosis of diffuse liver disease and characterization of morphologic changes is improved using contrast-enhanced MR imaging with liver specific contrast media. Combined magnetic resonance imaging can provide comprehensive evaluation of cirrhosis. An improved detection rate and characterization of regenerating nodules can be achieved compared to imaging modalities such as ultrasound and computed tomography. MR imaging can be performed in a one-stop-technique using unenhanced and liver-specific-contrast-enhanced sequence protocols to evaluate the liver parenchyma itself, MR cholangiography to verify the bile duct system, and MR angiography to specify the vascular situation. This technique is the optimal protocol for diagnostic imaging in patients suffering from liver cirrhosis and the method of choice to reach the final diagnosis.     

Enhanced tumor detection in the presence of fatty liver disease: Cell-specific contrast agents

It is assumed that hepatobiliary, cell-specific contrast agents will be adversely affected by the presence of diffuse liver disease. The diagnostic efficacy for tumor detection in the presence of fatty liver disease was experimentally studied at contrast-enhanced magnetic resonance (MR) imaging with manganese-DPDP (N,N′-dipyridoxylethylenediamine-N,N′-diacetate 5,5′-bis[phosphate]) and gadobenate dimeglumine (Gd-BOPTA/dimeg) and compared with conventional and chemical shift imaging. Carcinosarcoma was implanted into the liver of rats, and fatty liver was induced with L-ethionine. Without contrast agents, the tumor-fatty liver contrast-to-noise ratio (C/N) was increased on T1-weighted and decreased on T2-weighted MR images relative to tumor-bearing control rats without fatty liver. Chemical shift imaging (phase-contrast method) increased the tumor—fatty liver C/N from 2.3 ± 1.0 to 6.1 ± 1.7 (P <.001). Mn-DPDP and Gd-BOPTA/dimeg increased the tumor—fatty liver C/N from -5.4 ± 1.6 to -11.0 ± 1.9 and ?9.8 ± 3.4, respectively (P <.001). The hepatobiliary, cell-specific contrast agents were equally effective in both fatty and nonfatty liver and outperformed both chemical shift and conventional MR imaging in detecting liver tumors.     

Enhancement characteristics of liver metastases, hepatocellular carcinomas, and hemangiomas with Gd-EOB-DTPA: preliminary results with dynamic MR imaging

Our objective was to study Gd-EOB-DTPA for the characterization of focal liver lesions by means of dynamic MR imaging. A double-blind and randomized dose-ranging phase-2 clinical trial was performed in 31 patients (liver metastases n = 23, hepatocellular carcinoma n = 4, and hemangioma n = 4) at a field strength of 1.0 Tesla. Gd-EOB-DTPA (Schering AG, Berlin, Germany) was administered as an IV bolus (12.5, 25, or 50 μmol/kg body weight) with dynamic T1-weighted MRI during the distribution and cellular uptake of the contrast agent at multiple time points up to 45 min post contrast. Dynamic changes in tumor signal intensity, tumor–liver contrast, enhancement patterns, side effects, and adverse events were evaluated. Monitoring of vital signs revealed no significant changes during bolus injection of Gd-EOB-DTPA. Liver metastases demonstrated an inhomogeneous uptake of Gd-EOB-DTPA during the distribution phase with a washout effect on delayed images > 3 min and highest tumor–liver contrast 20 and 45 min post contrast. Hepatocellular carcinomas showed prolonged enhancement as compared with metastases and hemangiomas. Hemangiomas exhibited an early peripheral–nodular enhancement with subsequent partial or complete filling, persisting enhancement < 10 min following injection of Gd-EOB-DTPA, and delayed washout as compared with liver metastases. Initial clinical experience suggests that Gd-EOB-DTPA as a bolus injectable hepatobiliary MR contrast agent may offer useful features for the characterization of focal liver lesions. Received 4 January 1996; Revision received 13 March 1996; Accepted 4 June 1996     

Screening for bone metastases: whole-body MRI using a 32-channel system versus dual-modality PET-CT

The diagnostic accuracy of screening for bone metastases was evaluated using whole-body magnetic resonance imaging (WB-MRI) compared with combined fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (FDG-PET-CT). In a prospective, blinded study, 30 consecutive patients (18 female, 12 male; 24–76 years) with different oncological diseases and suspected skeletal metastases underwent FDG-PET-CT as well as WB-MRI with the use of parallel imaging (PAT). With a 32-channel scanner, coronal imaging of the entire body and sagittal imaging of the complete spine was performed using T1-weighted and short tau inversion recovery (STIR) sequences in combination. PET-CT was conducted using a low-dose CT for attenuation correction, a PET-emission scan and diagnostic contrast-enhanced CT scan covering the thorax, abdomen and pelvis. Two radiologists read the MRI scans, another radiologist in combination with a nuclear medicine physician read the PET-CT scans, each in consensus. The standard of reference was constituted by radiological follow-up within at least 6 months. In 28 patients, 102 malignant and 25 benign bone lesions were detected and confirmed. WB-MRI showed a sensitivity of 94% (96/102), PET-CT exams achieved 78% (79/102; P<0.001). Specificities were 76% (19/25) for WB-MRI and 80% (20/25) for PET-CT (P>0.05). Diagnostic accuracy was 91% (115/127) and 78% (99/127; P<0.001), respectively. Cut-off size for the detection of malignant bone lesions was 2 mm for WB-MRI and 5 mm for PET-CT. WB-MRI revealed ten additional bone metastases due to the larger field of view. In conclusion, WB-MRI and FDG-PET-CT are robust imaging modalities for a systemic screening for metastatic bone disease. PAT allows WB-MRI bone marrow screening at high spatial resolution and with a diagnostic accuracy superior to PET-CT.     

Small colorectal liver metastases: Detection with SPIO-enhanced MRI in comparison with gadobenate dimeglumine-enhanced MRI and CT imaging

The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1 cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs seperately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1 cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.     

Congenital neuroblastoma: evaluation with multimodality imaging

The authors retrospectively evaluated 12 patients with congenital (neonatal) neuroblastoma to assess the utility of newer imaging modalities. Findings at prenatal ultrasound (US), performed in four patients, were nonspecific (hydramnios and hydrops fetalis) in two and consistent with a suprarenal mass (one solid, one cystic) in the other two. Postnatal US helped accurately detect adrenal tumors (solid or complex, with one exception) but was less accurate in the diagnosis of metastatic disease to the liver. Computed tomography accurately depicted all primary tumors and liver metastases. Magnetic resonance (MR) imaging helped establish the correct diagnosis in three patients. This study again confirmed the benign course of neonatal neuroblastoma, with 50% of the patients classified with stage IV-S disease and two deaths occurring in the series, both due to complications. Therefore, aggressive diagnostic imaging is less desirable, and US is therefore very useful, despite its limitations. The prenatal detection and solid appearance of a suprarenal mass makes the diagnosis of neuroblastoma very likely, as does the presence of liver lesions. In the absence of these characteristic findings, US should be repeated to exclude adrenal hemorrhage. MR imaging seems to be a good alternative in some instances.