PET/CT for the characterization of adrenal masses in patients with cancer: qualitative versus quantitative accuracy in 150 consecutive patients.

OBJECTIVE: The objective of our study was to evaluate a large cohort of patients with PET/CT to determine whether qualitative (visual) assessment, quantitative standardized uptake value (SUV), or standardized uptake ratio (SUR) techniques should be used when attempting to characterize adrenal masses in patients with cancer. MATERIALS AND METHODS: The study group was composed of 150 consecutive patients (78 men, 72 women; mean age, 60 years; range, 24-88 years) with documented adrenal lesions. All patients were known to have an underlying primary malignancy and were referred for PET/CT to evaluate the underlying primary and metastatic tumor burden. Definitive lesion characterization was determined by evaluating all histologic adrenal specimens and all relevant prior and follow-up CT scans, including unenhanced, contrast-enhanced, and delayed contrast-enhanced washout studies. RESULTS: Of the 139 benign lesions, 109 were considered benign by CT densitometry measurements and 135 by qualitative PET data. Qualitative PET characterized 28 of 30 benign lesions that were considered indeterminate by unenhanced CT. All 26 malignant lesions were characterized by PET: All showed qualitative and quantitative signal intensity greater than the liver. By combining unenhanced and qualitative CT data with the retrospective PET data, the analysis yielded a sensitivity of 100% for the detection of malignancy, a specificity of 99%, a positive predictive value (PPV) of 93%, a negative predictive value (NPV) of 100%, and an accuracy of 99% (Table 1). Conversely, for the detection of benignity, the sensitivity, specificity, PPV, NPV, and accuracy were 99%, 100%, 100%, 93%, and 99%, respectively. CONCLUSION: PET/CT is a highly accurate method for differentiating benign from malignant adrenal masses particularly when using qualitative, rather than quantitative, PET data. The routine use of quantitative mean or maximal SUV or SUR data may be unnecessary. Occasional benign lesions do show mild to moderate increased FDG uptake compared with that of the liver and may mimic some malignant lesions. Without evidence that these lesions are benign by unenhanced CT densitometry or adrenal mass stability or growth from previous CT scans, we recommend that these lesions be characterized using contrast-enhanced washout tests and that if those tests are inconclusive, using percutaneous biopsy if early lesion characterization is mandatory.

Lymph node staging in esophageal adenocarcinoma with PET-CT based on a visual analysis and based on metabolic parameters.

BACKGROUND: In order to investigate the value of FDG positron emission tomography-computed tomography (PET-CT), FDG PET (reviewed side-by-side with CT), and metabolic parameters in the assessment of lymph node status and prognosis. METHODS: Fifty-five subjects with lymph node positive (N1) and 26 subjects with lymph node negative (N0) disease were included. In the slice with the maximum FDG uptake of the tumor, the axial area of the primary tumor, the maximum diameter of the tumor, and the mean and maximum standardized uptake values were measured. RESULTS: Fused PET-CT correctly characterized 289 of 325 lymph node groups (accuracy 89%) compared to 273 of 325 with PET (accuracy 84%). In lymph node staging (N0 vs. N1), PET-CT (accuracy 83%) was more accurate than PET (accuracy 78%). Among the metabolic parameters, the tumor diameter measured on PET-CT was the best predictor of lymph node stage (N0 vs. N1: accuracy 86%; threshold 25.5 mm) and overall survival. However, the highest accuracy of lymph node staging (N0 vs. N1) was achieved with the synergistic combination of visual analysis and primary tumor diameter measurements (accuracy 95%). CONCLUSIONS: PET-CT increases accuracy of lymph node staging in esophageal adenocarcinoma compared to PET. The primary tumor diameter further improves accuracy in lymph node staging and was shown to be an independent predictor of overall survival.

Adenocarcinomas of the esophagus: response to chemoradiotherapy is associated with decrease of metabolic tumor volume as measured on PET-CT. Comparison to histopathologic and clinical response evaluation.

PURPOSE: We determined whether evaluation of treatment response is feasible by measuring metabolic tumor volume parameters on 18F-FDG (Fluorodeoxyglucose) PET-CT (Positron emission tomography-Computed tomography). We compared the response evaluation based on metabolic tumor volume parameters to a histopathologic and clinical response evaluation (clinical response criteria: RECIST criteria=Response evaluation criteria in solid tumors, and WHO criteria=World health organization). PATIENTS AND METHODS: A total of 51 study subjects with adenocarcinomas (Type I due to Siewert classification) of the esophagus underwent PET-CT scans before and after neoadjuvant chemoradiotherapy. Tumor volume, maximum and mean standardized uptake values (SUV) were assessed before and after chemoradiotherapy. Furthermore, the total lesion glycolysis (TLG) was calculated by multiplying the tumor volume by the mean SUV of the volume. Clinical response evaluation was performed with endoscopic ultrasound and CT using RECIST and WHO criteria. The reference standard for treatment response was the postsurgical histopathology. RESULTS: The decrease of tumor volume between the pre- and post-treatment PET-CT scans was a better predictor of histopathologic response and survival than the decrease of the SUV and of the clinical response evaluation based on RECIST and WHO criteria. The highest accuracy, however, was achieved when using the TLG for the identification of treatment responders. A decrease of the TLG by > 78% between pre- and post-therapy scans predicted histopathologic response with a sensitivity and specificity of 91% and 93%, respectively. CONCLUSIONS: Tumor volume and TLG can be used to assess treatment response and survival in patients with esophageal adenocarcinoma.

Diffusion MRI of uterine and ovarian masses: identifying the benign lesions.

PURPOSE: The purpose of the study was to assess the diagnostic performance of qualitative and quantitative diffusion-weighted imaging (DWI) in differentiating benign from malignant ovarian and uterine masses. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant retrospective study, with waiver of informed consent. DWI MRIs of 222 women acquired over 1.5 years were evaluated. Reference standard was pathology or follow-up imaging. For qualitative assessment, two radiologists independently reviewed DWI and apparent diffusion coefficient (ADC) images for diffusion restriction. Differences were resolved by consensus. For quantitative assessment, a single reader measured ADC values. Readers were blinded to the reference standard. RESULTS: 222 lesions, 121 ovarian (99 benign and 22 malignant) and 101 uterine (54 benign and 47 malignant), were included. Final diagnosis was established with pathology in 129 (58%) or with imaging follow-up in 93 (42%). Mean (range) follow-up interval was 27 (13-48) months. Qualitative assessment yielded sensitivity (ratio, 95% CI), specificity, PPV and NPV of 100% (22/22, 85-100), 68% (68/99, 58-76), 41% (22/54, 27-54), and 100% (68/68, 94-100) for ovarian and 94% (44/47, 83-98), 91% (49/54, 80-96), 90% (44/49, 78-95) and 94% (49/52, 84-98) for uterine malignancies. ADC (mean ± SD) between benign ovarian [(1.11 ± 0.76) × 10-3 mm2/s] vs. malignant [(0.71 ± 0.26) × 10-3 mm2/s] lesions was significantly different (p < 0.001). ADC cutoff value of 1.55 × 10-3 mm2/s for ovarian lesions resulted in 99.9% confidence for the absence of malignancy. ADC (mean ± SD) of benign uterine [(0.64 ± 0.38) × 10-3 mm2/s] vs. malignant [(0.68 ± 0.19) × 10-3 mm2/s] lesions was not significantly different (P < 0.54). CONCLUSION: Quantitative and qualitative DWI assessment can be used to confidently characterize a subset of ovarian lesions as benign. With uterine lesions, although DWI is useful in differentiating benign from malignant lesions, the technique does not allow for definitive quantitative characterization.

Imaging of acute mesenteric ischemia using multidetector CT and CT angiography in a porcine model.

Acute mesenteric ischemia, a frequently lethal disease, requires prompt diagnosis and intervention for favorable clinical outcomes. This goal remains elusive due, in part, to lack of a noninvasive and accurate imaging study. Traditional angiography is the diagnostic gold standard but is invasive and costly. Computed tomography (CT) is readily available and noninvasive but has shown variable success in diagnosing this disease. The faster scanning time of multidetector row CT (M.D.CT) greatly facilitates the use of CT angiography (CTA) in the clinical setting. We sought to determine whether M.D.CT-CTA could accurately demonstrate vascular anatomy and capture the earliest stages of mesenteric ischemia in a porcine model. Pigs underwent embolization of branches of the superior mesenteric artery, then imaging by M.D.CT-CTA with three-dimensional reconstruction protocols. After scanning, diseased bowel segments were surgically resected and pathologically examined. Multidetector row CT and CT angiography reliably defined normal and occluded mesenteric vessels in the pig. It detected early changes of ischemia including poor arterial enhancement and venous dilatation, which were seen in all ischemic animals. The radiographic findings--compared with pathologic diagnoses-- predicted ischemia, with a positive predictive value of 92%. These results indicate that M.D.CT-CTA holds great promise for the early detection necessary for successful treatment of acute mesenteric ischemia.

Early antiangiogenic activity of bevacizumab evaluated by computed tomography perfusion scan in patients with advanced hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is a highly vascularized tumor with a poor prognosis. In a phase II study that combined bevacizumab with gemcitabine and oxaliplatin in advanced HCC, we examined computed tomography perfusion (CTp) scan parameters as surrogate markers of angiogenesis after bevacizumab administration. METHODS: HCC patients received bevacizumab alone i.v. at 10 mg/kg on day 1 during cycle 1. CTp scanning was performed at baseline and days 10-12 to assess changes in tissue blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface area product (PS). RESULTS: Compared with baseline, a significant decrease in the estimated tumor perfusion parameters including BF, BV, and PS and an increase in MTT were seen on days 10-12 following bevacizumab administration alone. Patients with progressive disease had lower baseline MTT values and a higher percent increase following bevacizumab administration than those with stable disease or partial responses. CONCLUSIONS: Bevacizumab induced a significant decrease in tumor BF, BV, and PS and an increase in MTT by CTp scan in HCC. Baseline and percent change in MTT following bevacizumab administration correlated with clinical outcome, whereas BF, BV, and PS did not.