F-18 FDG positron emission tomography in non-Hodgkin lymphoma of the breast

The breast is an uncommon site of development of extranodal non-Hodgkin lymphoma (NHL). Both primary and secondary involvement of the breast have been reported. A 36-year-old woman diagnosed with NHL underwent multimodality imaging for staging of the disease. CT of the chest revealed no significant abnormalities. Whole-body FDG PET imaging showed intense FDG uptake in the left breast. Cytologic examination confirmed breast involvement by diffuse large B-cell NHL. Although rare, breast involvement characterized by increased FDG uptake can occur in patients with lymphoma. This case highlights the role of FDG PET in patients with suspected lymphoma in dense breasts that can be missed by CT scan and mammogram.     

Follow-up FDG PET in the evaluation of unexplained focal activity in the abdomen

PURPOSE: This study assessed the value of a follow-up FDG PET scan when the initial PET demonstrated unexplained findings of focal FDG uptake in the abdomen. METHOD: The records of 3634 patients with PET scans were retrospectively reviewed. Those patients who had follow-up PET scans after the initial PET scan showed unexplained FDG activity in the abdomen were further analyzed. The results from the second PET scan were compared with the follow-up data, which included the findings from other imaging modalities, clinical course, and biopsy or surgical pathology interpretations. RESULTS: A total of 59 patients were included in the final analysis. The average time interval between the initial and the follow-up PET scans was 4.2 + 2.3 months. The follow-up PET provided a clear-cut diagnosis in 55 (93.2%) of these patients, whereas diagnoses in only 4 patients remained indeterminate. Follow-up PET scans were negative for abdominal malignancy in 38 patients. Thirty-five of these 38 patients with negative follow-up PET were proven to be without abdominal malignancy, with a negative predictive value of 92.1% (35 of 38). The follow-up PET was positive in 17 patients. Fifteen of these 17 patients with a positive follow-up PET scans were found to have malignancy in the abdomen with a positive predicative value of 88.2% (15 of 17). All 4 patients with indeterminate follow-up scans were proven not to have malignancy. CONCLUSION: Follow-up FDG PET scan provides an effective means for diagnosing unexplained findings in the abdomen that were previously detected on initial PET scan.     

Dual time point 18F-FDG PET imaging detects breast cancer with high sensitivity and correlates well with histologic subtypes.

This prospective study was designed to assess the utility of the dual time point imaging technique by (18)F-FDG PET in detecting primary breast cancer and to determine whether there is a relationship between (18)F-FDG uptake and its change over time and the histopathologic subtypes. METHODS: One hundred fifty-two patients with newly diagnosed breast cancer underwent 2 sequential PET scans (dual time point imaging) for preoperative staging. The maximum standardized uptake value (SUVmax) of (18)F-FDG was measured from both time points. The percent change in SUVmax (Delta%SUVmax) between time points 1 (SUVmax1) and 2 (SUVmax2) was calculated. Patients were divided into 2 groups according to histopathology as invasive and noninvasive. Invasive tumors were also divided into 2 groups (>10 mm and 4-10 mm). The tumor-to-contralateral normal breast (background) ratios of SUVmax at both time points for groups were measured and the Delta%SUVmax values were calculated. RESULTS: The mean +/- SD of the SUVmax1, the SUVmax2, and the Delta%SUVmax were 3.9 +/- 3.7, 4.3 +/- 4.0, and 8.3% +/- 11.5% for invasive; 2.0 +/- 0.6, 2.1 +/- 0.6, and 3.4% +/- 13.0% for noninvasive; and were 1.2 +/- 0.3, 1.1 +/- 0.2, and -10.0% +/- 10.8% for the contralateral normal breast groups, respectively. In the comparison of SUVmax1, Delta%SUVmax, and the tumor-to-background ratios among groups, all results were significant (P < 0.001). Visual assessment revealed that the sensitivity of dual time point imaging was 90.1% for invasive cancer >10 mm, 82.7% for invasive breast cancers 4-10 mm, and 76.9% for noninvasive breast cancers. CONCLUSION: Dual time point imaging is a simple and noninvasive method that may improve the sensitivity and accuracy of (18)F-FDG PET in assessing patients with primary breast cancer. The changes that are noted in SUVs in dual time point imaging vary depending on the histopathologic type of primary breast cancer.     

18F-FDG PET for evaluation of the treatment response in patients with gastrointestinal tract lymphomas.

(18)F-FDG PET is highly sensitive and specific for evaluation of the treatment response of nodal and extranodal diseases in patients with malignant lymphomas. However, no data are available in the literature with regard to (18)F-FDG PET for evaluation of the treatment response in patients with lymphomas with gastrointestinal tract (GIT) involvement. This study was undertaken to investigate the usefulness of (18)F-FDG PET in monitoring the response to the treatment of lymphomas in this setting. METHODS: We retrospectively analyzed 19 patients with different types of lymphomas (10 diffuse large B-cell lymphomas, 4 follicular lymphomas, 3 mantle cell lymphomas, and 2 Hodgkin's disease) involving GIT. Among 19 patients, 4 had gastric involvement, 13 had small bowel involvement, and 2 had small bowel plus colon involvement by lymphomas. All patients underwent (18)F-FDG PET before and after the completion of therapy. The results of (18)F-FDG PET were compared with the results of CT and clinical outcome; the presence of relapse was determined on the basis of positive biopsy results or clinical follow-up data. RESULTS: Of the 19 posttreatment PET scans, 13 showed no pathologic (18)F-FDG uptake, whereas 6 showed persistent (18)F-FDG uptake. Among the 13 patients who had negative PET scans, only 1 patient (7.7%) relapsed, whereas all 6 patients (100%) who had persistent abnormal (18)F-FDG uptake on posttherapy PET scans relapsed. Posttreatment CT scans were negative for 10 patients but showed persistent disease in the remaining 9 patients. Among the 10 patients who had negative CT scans, 9 remained in remission and 1 (10%) relapsed. Of the 9 patients who showed persistent disease, 6 (67%) relapsed and 3 (33%) remained in remission after the mean follow-up of 20 mo. The sensitivity, specificity, positive and negative predictive values, and accuracy of posttherapy (18)F-FDG PET were 86%, 100%, 100%, 92%, and 95%, respectively. The corresponding values for CT were 67%, 75%, 75%, 90%, and 79%, respectively. Patients with positive (18)F-FDG PET results had statistically significantly lower disease-free survival (DFS) (0%) than did those with positive CT results (33%) (P = 0.04). There was no statistically significant difference in DFS between patients with negative (18)F-FDG PET results and patients with negative CT results. CONCLUSION: A positive (18)F-FDG PET scan after the completion of chemotherapy in patients with lymphomas with GIT involvement is a strong predictor of relapse. (18)F-FDG PET has higher diagnostic accuracy than CT in the detection of residual disease after therapy. Despite the mild physiologic (18)F-FDG uptake in the GIT, (18)F-FDG PET has potential value in monitoring the response to treatment in patients with GIT lymphomas, particularly when pretreatment PET results are positive.     

Metachronous, multicentric giant cell tumor of the sphenoid bone with histologic, CT, MR imaging, and positron-emission tomography/CT correlation

Giant cell tumor (GCT) of the sphenoid bone is a relatively rare entity and metachronous multicentric GCT of the sphenoid is even rarer; we are aware of only 3 previous cases in the literature. We describe here a tumor of the sphenoid bone that was identified 15 years after multiple resections of a GCT of the left inferior pubic ramus. Correlation is made between the histopathologic findings, MR imaging of the brain, CT of the head, and fusion positron-emission tomography (PET)/CT scan performed with fluorine-18 fluoro-2-deoxy-D-glucose (18F-FDG). This report is the first to describe the appearance of a GCT of the sphenoid bone on a fusion PET/CT examination. High metabolic activity in the base of the skull adjacent to the middle cranial fossa was demonstrated in a fashion similar to that of the known pelvic lesion. This case also demonstrates that the increased metabolic activity seen in a GCT of the sphenoid bone may be partially obscured by the adjacent physiologic high metabolic activity of the brain.     

Potential of Dual Time Point FDG-PET Imaging in Differentiating Malignant from Benign Pleural Disease

Aim  The aim of this study was to assess the utility of dual time point ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) imaging in differentiating benign from malignant pleural disease. Methods  Fifty-five consecutive patients of suspected malignant pleural mesothelioma (MPM) and recurrence of MPM who were referred for the evaluation underwent two sequential ¹⁸F-FDG-PET scans (dual time point imaging). The average percent change in the maximum standardized uptake values (Δ%SUVmax) of the lesion/lesions between time point 1 (SUV_max1) and time point 2 (SUV_max2) was calculated. All PET results were correlated with the histopathological or cytopathology results. Patients were divided into three principal groups (A = newly diagnosed MPM, B = recurrent MPM, and C = benign pleural disease). The parameters of ¹⁸F-FDG uptake (SUV_max values and its changes over time) were compared among groups. Results  Among the 55 patients who had undergone dual time point ¹⁸F-FDG-PET studies, 44 were diagnosed with MPM (28 newly diagnosed and 16 had recurrence). The PET studies demonstrated 229 malignant pleural lesions in these patients. The remaining 11 patients were proven to have benign pleural disease. The mean ± SD of the SUV_max1, SUV_max2, and the Δ%SUV_max of the all lesions of each patient in groups A, B, and C were 5.0 ± 2.2%, 5.8 ± 2.8%, and 12.8 ± 8.4%; 4.6 ± 1.7%, 5.3 ± 2.0%, 13.8 ± 9.2%; and 1.6 ± 0.4%, 1.4 ± 0.3%, and–9.6 ± 19.1%, respectively. The mean ± SD of the SUV_max1, SUV_max2, and Δ%SUV_max in patients with both newly diagnosed and recurrent MPM were significantly higher than those of benign pleural disease group (p < 0.0001). For each patient, the most intense (hottest) lesion’s SUV_max1, SUV_max2, and Δ%SUV_max were also compared among the aforementioned groups, and these results again confirmed that MPM lesions had significantly higher values than those of benign pleural lesions (p < 0.0001). Conclusions  There is an increasing uptake of ¹⁸F-FDG over time in pleural malignancies, whereas the uptake in benign pleural disease generally stays stable or decreases over time. Therefore, dual time point imaging appears to be an effective approach in differentiating benign from malignant pleural disease, which increases the sensitivity and is also helpful in guiding the biopsy site for a successful diagnosis.     

Catheter-Directed Thrombolysis in the Setting of Massive Iliofemoral Deep Vein Thrombosis: Case Study and Review

Catheter-directed thrombolytic (CDT) therapy has steadily grown in popularity as the primary intervention for certain types of acute or subacute deep vein thrombosis. In such cases, nurses within the interventional radiology department must sustain patient care during all phases of the procedure while also monitoring progression of clot lysis and different CDT therapies used by the physician. This article describes the 3-day treatment and management of a patient presenting with extensive bilateral iliofemoral thrombosis. Relevant anatomy, indications for CDT therapy, and specific nursing considerations are reviewed.     

A recovery coefficient method for partial volume correction of PET images

Objectives  Correction of the “partial volume effect” has been an area of great interest in the recent times in quantitative PET imaging and has been mainly studied with count recovery models based upon phantoms that incorporate hot spheres in a cold background. The goal of this research study was to establish a similar model that is closer to a biological imaging environment, namely hot spheres/lesions in a warm background and to apply this model in a small cohort of patients. Methods  A NEMA phantom with six spheres (diameters 1–3.7 cm) was filled with ¹⁸FDG to give sphere:background activity ratios of 8:1, 6:1, and 4:1 for three different acquisitions on a Philips Allegro scanner. The hot sphere SUVmax and the background average SUV were measured for calculation of recovery coefficients (RCs). Using the RCs, the lesion diameters, and the lesion:background ratio, the SUVmax of 64 lesions from 17 patients with biopsy proven lung cancer were corrected. Results  The RCs versus sphere diameters produced characteristic logarithmic curves for each phantom (RCs ranged from 80% to 11%). From a cohort of 17 patients with biopsy proven lung cancer, 64 lesions combined had a mean SUVmax of 7.0 and size of 2.5 cm. After partial volume correction of the SUVmax of each lesion, the average SUVmax increased to 15.5. Conclusions  Hot spheres in a warm background more closely resemble the actual imaging situation in a living subject when compared to hot spheres in a cold background. This method could facilitate generation of equipment specific recovery coefficients for partial volume correction. The clinical implications for the increased accuracy in SUV determination are certainly of potential value in oncologic imaging.     

Intense esophageal FDG activity caused by Candida infection obscured the concurrent primary esophageal cancer on PET imaging

Esophageal cancer frequently causes a focal intense FDG uptake on positron emission tomography (PET) imaging while esophagitis often results in a mild to moderate degree of FDG activity in a diffuse pattern. However, detection of an esophageal cancer can become difficult in the presence of a diffuse esophageal activity because of esophagitis. We present such case in which esophageal cancer superimposed by Candidal esophagitis is difficult to recognize on FDG PET images.