Computed tomography, magnetic resonance imaging and 11C-metomidate positron emission tomography for evaluation of adrenal incidentalomas

Background

Given the higher sensitivity of modern computed tomography (CT) scanners, adrenal incidentalomas are being discovered increasingly often. This implies a growing quantitative diagnostic and clinical problem. CT and/or magnetic resonance imaging (MRI) and usually thorough hormonal testing are routinely used to determine the origin of these lesions. Recently, positron emission tomography (PET) using the tracer ¹¹C-metomidate (MTO) has been established as an alternative diagnostic method with high sensitivity for identifying adrenocortical lesions. The aim of this study was to evaluate the clinical use and value of MTO-PET compared to CT and MRI in the characterisation and work-up of adrenal incidentalomas.

Methods

Initially, we retrospectively evaluated 20 adrenal incidentalomas in patients who had undergone CT, MRI and MTO-PET and from whom we had either histopathological diagnosis or clinical follow-up data. After this analysis we conducted a prospective study in order to compare the imaging modalities. In the latter study, 24 incidentalomas were imaged by CT, MRI and MTO-PET and the results were correlated to those from histopathology (n = 8) and clinical diagnosis after follow-up (n = 16).

Results

In the retrospective analysis, MRI and especially MTO-PET, correlated well to histopathology and clinical diagnosis after follow-up, whereas specificity with CT was low. This was possibly due to the presence of several haematomas/fibrosis which were misdiagnosed as adrenocortical adenomas. In the prospective cohort, sensitivity and specificity with CT were 0.71 and 1.0, respectively, and further characterisation by MRI increased these values to 0.86 and 1.0, whereas maximum sensitivity and specificity were reached when MTO-PET was added.

Conclusion

The diagnosis of an adrenocortical adenoma may be established by CT in most patients and by MRI in an additional number. For the few remaining patients needing further characterisation, MTO-PET is advantageous as an additional imaging modality.     

18F-fluorodeoxyglucose positron emission tomography in patients with recurrent ovarian cancer: in comparison with vascularity, Ki-67, p53, and histologic grade

The aim of this study was to assess the correlation between 18F-fluorodeoxyglucose positron emission tomography (FDG PET) positivity of tumor recurrence and vascularity, Ki-67, p53, and histologic grade in patients with ovarian cancer. Nineteen patients with recurrent ovarian cancer underwent FDG PET before second-look surgery. Archival paraffin-embedded tissue materials were used to assess histologic grade including architectural pattern, mitotic activity, and nuclear pleomorphism; intratumor microvessel density (MVD); Ki-67; and p53. Univariate analysis was used to evaluate the correlation between FDG PET positivity and each biomarker. Stepwise logistic regression analysis was used to determine the best parameter to explain FDG PET positivity. MVD revealed significant positive correlation with FDG PET positivity (p=0.0341). There was no significant correlation between FDG PET positivity and Ki-67 or p53 (p=0.4040, p=0.6027). Mitotic activity yielded statistically significant positive correlations with FDG PET positivity (p=0.0448) although histologic grade revealed no positive correlation (p=1). Stepwise logistic regression analysis revealed MVD to be the strongest parameter for FDG PET positivity (OR=0.696, 95% CI 0.487–0.993, p=0.0458). In conclusion, FDG PET positivity revealed positive correlation with MVD and mitotic activity. MVD was the strongest parameter in predicting positive tumor recurrence on FDG PET.     

Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography,magnetic resonance imaging,and positron emission tomography

We report a case of recurrent endodermal sinus tumor.of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed.     

Dynamic contrast-enhanced MRI of primary rectal cancer: quantitative correlation with positron emission tomography/computed tomography

Purpose

To assess the correlations between parameters measured on dynamic contrast‐enhanced magnetic resonance imaging and 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) in rectal cancer.

Materials and Methods

To assess the correlations between parameters measured on dynamic contrast‐enhanced MRI and FDG‐PET in rectal cancer.

Results

Significant correlations were only demonstrated between k_ep and SUVmax (r = 0.587, P = 0.001), and k_ep and SUVmean (r = 0.562, P = 0.002). No significant differences were found in imaging parameters between well, moderately and poorly differentiated adenocarcinoma groups. However, there was a trend that higher imaging values were found in poorly differentiated adenocarcinomas.

Conclusion

Positive correlations were found between k_ep and SUV values in primary rectal adenocarcinomas suggesting an association between angiogenesis and metabolic activity and further reflecting that angiogenic activity in washout phase is better associated with tumor metabolism than the uptake phase. J. Magn. Reson. Imaging 2011;33:340–347. © 2011 Wiley‐Liss, Inc.     

Advantages and pitfalls of 18F-fluoro-2-deoxy-D-glucose positron emission tomography in detecting locally residual or recurrent nasopharyngeal carcinoma: comparison with magnetic resonance imaging

Introduction This prospective study was designed to elucidate the advantages and pitfalls of ¹⁸F-FDG PET in detecting locally residual/recurrent nasopharyngeal carcinoma (NPC) in comparison with MRI. Methods We recruited NPC patients from two ongoing prospective trials. One is being performed to evaluate suspected local recurrence (group A) and the other to assess local treatment response 3 months after therapy (group B). Both groups received ¹⁸F-FDG PET and head and neck MRI. The gold standard was histopathology or clinical/imaging follow-up. An optimal cut-off standardised uptake value (SUV) was retrospectively determined. Results From January 2002 to August 2004, 146 patients were eligible. Thirty-four were from group A and 112 from group B. In all, 26 had locally recurrent/residual tumours. Differences in detection rate between ¹⁸F-FDG PET and MRI were not statistically significant in either group. However, ¹⁸F-FDG PET showed significantly higher specificity than MRI in detecting residual tumours among patients with initial T4 disease (p=0.04). In contrast, the specificity of ¹⁸F-FDG PET for patients with an initial T1–2 tumour treated with intracavitary brachytherapy (ICBT) was significantly lower than that for patients not treated by ICBT (72.2% vs 98.1%, p=0.003). At an SUV cut-off of 4.2, PET showed an equal and a higher accuracy compared with MRI in groups A and B, respectively. Conclusion ¹⁸F-FDG PET is superior to MRI in identifying locally residual NPC among patients with initial T4 disease but demonstrates limitations in assessing treatment response in patients with initial T1–2 disease after ICBT. A cut-off SUV is a useful index for aiding in the visual detection of locally residual/recurrent NPC.     

Ultrasonography, computed tomography and magnetic resonance imaging for diagnosis of ovarian carcinoma

Our objective was to compare US, CT, and MR imaging in differentiation of malignant from benign ovarian tumors. Through an electronic literature search and manual review of bibliographies (January 1990 to June 2006), relevant studies on the diagnostic performance of US, CT, and MR imaging in the differentiation between benign and malignant ovarian tumours were identified. Sixty-nine articles were included, yielding 143 studies. Data on the accuracy of the different imaging modalities were analyzed and compared by constructing summary receiver-operating characteristic (ROC) curves. Our results suggest that US techniques seems to be similar with CT and MRI in differentiation of malignant from benign ovarian tumors. The results also revealed that color Doppler flow imaging alone is significantly inferior to combined US techniques, morphologic assessment alone and contrast enhanced US in diagnosis of ovarian cancer. In conclusion, US morphologic assessment still is the most important and common modality in detect ovarian cancer.     

Computer tomography, magnetic resonance imaging, and positron emission tomography or positron emission tomography/computer tomography for detection of metastatic lymph nodes in patients with ovarian cancer: a meta-analysis

Objectives

To compare the diagnostic performances of computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET or PET/CT) for detection of metastatic lymph nodes in patients with ovarian cancer.

Methods

Relevant studies were identified with MEDLINE and EMBASE from January 1990 to July 2010. We estimated the weighted summary sensitivities, specificities, OR (odds ratio), and summary receiver operating characteristic (sROC) curves of each imaging technique and conducted pair-wise comparisons using the two-sample Z-test. Meta-regression, subgroup analysis, and funnel plots were also performed to explain the between-study heterogeneity.

Results

Eighteen eligible studies were included, with a total of 882 patients. PET or PET/CT was a more accurate modality (sensitivity, 73.2%; specificity, 96.7%; OR [odds ratio], 90.32). No significant difference was detected between CT (sensitivity, 42.6%; specificity, 95.0%; OR, 19.87) and MR imaging (sensitivity, 54.7%; specificity, 88.3%; OR, 12.38). Meta-regression analyses and subgroup analyses revealed no statistical difference. Funnel plots with marked asymmetry suggested a publication bias.

Conclusion

FDG-PET or FDG-PET/CT is more accurate than CT and MR imaging in the detection of lymph node metastasis in patients with ovarian cancer.     

Dual modality imaging of positron emission tomography-computed tomography (PET-CT) in evaluation of postoperative renal cancer patients

Objective

The aim of our study was to determine the role of PET-CT in detection of recurrence and metastasis of renal cell carcinoma.

Widespread metastases from sarcomatoid renal cell carcinoma detected by 18F-FDG positron emission tomography/computed tomography

We present a case of sarcomatoid renal cell carcinoma (RCC). Although preoperative computed tomography (CT) scans demonstrated small lung and pleural nodules and mediastinal lymphadenopathy, these findings were not conclusive for metastases. Whole-body fluorine-18 fluorodeoxyglucose positron emission tomography and CT (FDG-PET/CT) performed 15 days after right nephrectomy showed intense FDG uptake in the aforementioned lesions (lung and pleural nodules, mediastinal lymph nodes). Unexpectedly, focal increased FDG uptake was found in the right infraspinatus muscle. FDG-PET/CT was considered useful for evaluating distant metastases and thus portending the aggressive nature of sarcomatoid RCC.