Preliminary clinical assessment of dynamic 18F-fluorodeoxyglucose positron-emission tomography/computed tomography for evaluating the clinicopathological grade in patients with non-Hodgkin's lymphoma: a prospective study.

OBJECTIVE: We prospectively assessed the diagnostic capacity of dynamic and dual-time-point F-fluorodeoxyglucose PET/computed tomography and explored the most appropriate scan timing for clinicopathological discrimination of non-Hodgkin's lymphoma. METHODS: Thirteen patients underwent dynamic scans dynamic scans (5-15, 15-25, and 25-35 minute postinjection) and consecutive dual-time-point scans (1- and 2-hour postinjection). For five indolent and 16 aggressive lymphomas, we statistically compared the maximum standardized uptake value (SUVmax) and the retention index of the SUVmax (RI-SUVmax) for each scan and explored the diagnostic capacities using receiver operating characteristic (ROC) curve analyses. RESULTS: SUVmax increased progressively over time in all lymphomas and was significantly higher for aggressive lymphoma than for indolent lymphoma in each timephase. RI-SUVmax of dynamic scans (RI-SUV-dynamic) was significantly higher in aggressive than in indolent lymphoma. The cutoff values obtained a sensitivity of 94%, positive-predictive value of 94%, and accuracy of 91% for SUVmax analyses of the dynamic second and third phases, 1-hour early phase, and 2-hour delayed phase, and a sensitivity of 88%, positive-predictive value of 93%, and accuracy of 86% for RI-SUV-dynamic. In contrast, for the dynamic first phase, the cutoff value of SUVmax yielded moderate sensitivity of 69%, a positive-predictive value of 92%, and an accuracy of 71%. The area under the ROC curve (AUC) of the RI-SUV-dynamic had the highest value (0.938), whereas the AUCs of the other ROC analyses were not significantly different. CONCLUSION: The dynamic second and third phase could potentially provide good predictors of clinicopathological discrimination, as can the early and delayed phases.

A reduced liver 18F-FDG uptake may be related to hypoalbuminemia in patients with malnutrition.

OBJECTIVE: 18F-FDG PET/CT is a hybrid imaging method widely used as a useful, noninvasive imaging modality for evaluating various neoplastic diseases. When assessing the tumor uptake, the liver and the mediastinal blood pool are often used as a reference region. In daily clinical practice, the 18F-FDG uptake in the liver sometimes appears to decrease on PET images of patients with malnutrition. The purpose of this study was to investigate whether or not the liver 18F-FDG uptake is decreased in patients with malnutrition. METHODS: We retrospectively analyzed 246 patients who underwent 18F-FDG PET/CT from January 2018 to June 2018 and whose blood serum albumin was measured within 1 month of PET/CT. We compared the liver uptake and mediastinal blood uptake of patients with low serum albumin level (< 4.0 g/dl) and hypoalbuminemia (< 3.5 g/dl) with those with a normal serum albumin level (≥ 4.0 g/dl). Correlations between the liver and mediastinal blood uptake and the serum albumin level were also calculated. RESULTS: The maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean) of the liver in 117 patients with low serum albumin were 3.1 ± 0.5 and 2.3 ± 0.3, respectively, while they were 2.9 ± 0.4, 2.0 ± 0.3 in 29 patients with hypoalbuminemia; these values were all significantly lower than the respective ones (3.4 ± 0.5, 2.5 ± 0.4) in 129 patients with normal serum albumin (all p < 0.001). The SUVmean of the mediastinal blood uptake in patients with hypoalbuminemia and normal serum albumin were 1.6 ± 0.2 and 1.7 ± 0.3, respectively (p = 0.053). The serum albumin level demonstrated a significantly positive, moderate correlation with the liver SUVmean, showing a regression line of y = 0.31x + 1.1 (r = 0.41, p < 0.001). CONCLUSION: The liver 18F-FDG uptake tended to decrease in patients with hypoalbuminemia. In the patients with malnutrition, the mediastinal blood pool may be a more stable reference than the liver for evaluating the tumor activity because hypoalbuminemia is considered to less strongly influence the mediastinal blood pool than that in the liver.

Preliminary clinical assessment of dynamic 18F-fluorodeoxyglucose positron emission tomography/computed tomography for evaluating lymph node metastasis in patients with lung cancer: a prospective study.

OBJECTIVE: We assessed the diagnostic capacity of dynamic fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and dual-time-point (DTP) PET/CT to explore the optimal scan timing for nodal staging in lung cancer. METHODS: Thirty-four patients with lung cancer underwent dynamic and consecutive DTP PET/CT scans. Two readers visually evaluated FDG uptake within each lymph node (LN) and pulmonary artery (metastatic LN: n = 10; nonmetastatic LN: n = 121). For each dynamic and DTP scan, we compared the maximum standardized uptake value (SUVmax) and the retention index of the SUVmax (RI-SUVmax) between metastatic and nonmetastatic LNs. We compared the diagnostic capacity of the dynamic and DTP scans using receiver operating characteristic (ROC) analyses. RESULTS: In the visual analyses of LN metastases, a sensitivity of 20.0-60.0% and specificity of 97.5-100.0% were identified for the first to third dynamic scans. The sensitivity of the 1-h early and 2-h delayed scans was 80.0% and 90.0%, respectively, whereas the specificity was 66.9% and 47.9%, respectively. The visual analysis of the dynamic second phase had the highest accuracy. Semiquantitative analyses revealed that the SUVmax was significantly higher for metastatic LNs than for nonmetastatic LNs in the dynamic second and third phases and the 1-h early and 2-h delayed phases (p < 0.05 for all). The RI-SUVmax was higher in metastatic LNs than in nonmetastatic LNs for the dynamic scan (p = 0.004) and the DTP scan (p = 0.002). The ROC analyses showed that SUV2 and SUV3 had higher performances with high specificity, high negative predictive value, and high accuracy than the other parameters. The area under the ROC curve of the RI-SUV-dual-time-point had the highest value (0.794) without any significant differences between the area under the ROC curves for all parameters (p > 0.05 for all). CONCLUSIONS: Based on the visual and semiquantitative analyses, 18F-FDG dynamic PET/CT exhibited excellent performance with extremely high specificity in the dynamic second phase.

Increased (18)F-fluorodeoxyglucose accumulation in bilateral adrenal glands of the patients suffering from vasovagal reaction due to blood vessel puncture.

OBJECTIVE: The purpose of the study was to evaluate the hypothesis that patients having a vasovagal reaction (VVR) after blood vessel puncture show increased FDG accumulation in bilateral adrenal glands. METHODS: Over the past 8 years, 26 patients experienced a VVR after blood vessel puncture following intra-venous injection of FDG at our institution. Of the 26 patients, 16 underwent multiple-occasion FDG-PET/CT scans while suffering a VVR at only one examination. All 16 patients had no morphological abnormality in the adrenal glands on FDG-PET/CT and follow-up examination. For the 16, we retrospectively reviewed the FDG-PET/CT scan with respect to the adrenal glands and compared the result to that for the FDG-PET/CT scan of the same patient when there was no VVR event. We used both visual analysis and semi-quantitative analysis employing either maximum standardized uptake value (SUVmax) or adrenal-to-liver (A/L) SUVmax ratio. RESULTS: On visual analysis of the FDG-PET/CT with VVR, accumulations in both of the adrenal glands was judged positive, defined as higher than the hepatic accumulation, in 84 % of the cases. The SUVmax in the right adrenal gland was 2.79 ± 0.69 with VVR and 1.92 ± 0.33 without VVR; this value in the left adrenal gland was 3.07 ± 0.71 with VVR and 2.05 ± 0.39 without. Mean SUVmax of both adrenal glands was 2.93 ± 0.66 with VVR and 1.98 ± 0.35 without. The A/L SUVmax ratio in the right adrenal gland was 1.02 ± 0.26 with VVR and 0.69 ± 0.11 without; this value in the left was 1.11 ± 0.23 with VVR and 0.74 ± 0.15 without. The mean A/L SUVmax ratio of both adrenal glands was 1.06 ± 0.24 with VVR and 0.72 ± 0.13 without. Each parameter with VVR was significantly higher than that without. For the two adrenal glands, the mean SUVmax with VVR was 48 % higher than that without VVR. CONCLUSIONS: We confirmed the hypothesis that patients having a VVR after blood vessel puncture show increased FDG accumulation in their bilateral adrenal glands. This may reflect hyper-metabolism of the adrenal glands in synthesizing and secreting catecholamine.

The physiological uptake pattern of (18)F-FDG in the left ventricular myocardium of patients without heart disease.

PURPOSE: The purpose of this study was to evaluate the physiological uptake pattern of (18)F-FDG in the left ventricular myocardium of patients under preparation for tumor FDG-PET. PATIENTS AND METHODS: We enrolled 188 patients without cardiac disease. The accumulation patterns were classified as either 'none', 'diffuse', 'focal' or 'focal on diffuse'. When a focal uptake was only observed on the basal wall, then the patterns were classified as having either a 'ring', 'over half' or 'spot' uptake. RESULTS: The frequencies of the myocardial FDG uptake patterns were as follows: none, n=52 (27.7%); diffuse, n=63 (33.5%); focal on diffuse, n=40 (21.3%) and focal, n=33 (17.6%). The age, blood glucose level, weight and dose of FDG did not differ significantly for each pattern. The focal and focal on diffuse patterns were seen in 73 patients, and 65 patients had a focal uptake only on the basal wall; ring uptake in 29 patients, over half in 20 and spot uptake in 16 patients. CONCLUSIONS: The physiological myocardial uptake showed several patterns. Focal uptake was often seen in patients with cardiac disease, but it did not always indicate an abnormal finding when the accumulation was only on the basal wall.

Comparing the performance of visual estimation and standard uptake value of F-18 fluorodeoxyglucose positron emission tomography/computed tomography for detecting malignancy in pancreatic tumors other than invasive ductal carcinoma.

INTRODUCTION: The utility of FDG PET/CT for the detection and evaluation of invasive ductal carcinoma has been widely reported, but a few studies have assessed the utility of FDG PET/CT to detect malignancy in a variety of pancreatic lesions other than invasive ductal carcinoma. PURPOSE: To compare the diagnostic performance of visual estimation with the semi-quantitative scores of FDG PET/CT for detecting malignancy in a variety of pancreatic lesions other than invasive ductal carcinoma. MATERIAL AND METHODS: Images of pathologically proven pancreatic lesions from 32 patients were retrospectively evaluated: 14 benign lesions, 7 borderline (low malignant) lesions, and 11 malignant lesions. The average scores from visual estimation by the two observers were compared to two semi-quantitative analyses of FDG uptake in the lesions, namely the maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean). RESULTS: Visual analysis value, SUVmax and SUVmean were 0.33 ± 0.21, 1.8 ± 0.7 and 1.5 ± 0.7 for the benign lesions, 0.70 ± 0.28, 5.0 ± 2.6 and 3.1±1.7 for the borderline lesions, and 0.73 ± 0.18, 4.7 ± 2.5 and 3.2 ± 1.6 for the malignant lesions, respectively. Receiver operating characteristic analysis revealed the areas under the curves for detecting non-benign (malignant or borderline) lesions through visual analysis, SUVmax, and SUVmean were 0.914, 0.954, and 0.875, respectively. CONCLUSION: For a variety of pancreatic lesions other than invasive ductal carcinoma, visual analysis and semi-quantitative analyses all showed strong diagnostic performance. However, semi-quantitative analysis with SUVmax proved to be the most effective method for detecting non-benign pancreatic lesions.

Correlations between F-18 FDG PET/CT and pathological findings in soft tissue lesions.

OBJECTIVE: To evaluate the correlations between F-18 FDG uptake imaged with PET/CT and pathological findings in soft tissue lesions. METHODS: Fifty-four soft tissue lesions in 47 patients were evaluated. The correlations between the degree of FDG uptake, pathological type and grade, and MRI signal intensity and/or enhancement pattern were evaluated. Tumor FDG uptake was quantified by the maximum standardized uptake value (SUVmax). RESULTS: Thirty-one lesions were malignant and twenty-three lesions were benign. The difference between SUVmax in the malignant and benign groups was statistically significant (p<0.001). Malignant myxoid lesions and well differentiated liposarcoma showed low FDG uptake. Benign neurogenic lesions showed low FDG uptake while malignant neurogenic tumors showed high FDG uptake, and the difference between SUVmax in the benign and malignant lesions was statistically significant (p<0.001). In a neurofibromatosis type-1 patient who had multiple neurogenic tumors, FDG-PET/CT could distinguish malignant peripheral nerve sheath tumors from other benign lesions with similar MRI findings. CONCLUSIONS: FDG-PET/CT is useful for differentiating malignant from benign soft tissue lesions, but malignant soft tissue lesions may show various patterns on FDG-PET, and MRI may be helpful for a differential diagnosis.

(18)F-2-fluoro-2-deoxyglucose uptake in or adjacent to blood vessel walls.

Incidental (18)F-2-fluoro-2-deoxyglucose (FDG) uptake in blood vessel walls is sometimes demonstrated during routine oncologic imaging with positron emission tomography/computed tomography (PET/CT). FDG uptake in vessel walls can also be seen under some non-physiological conditions such as vasculitis and arteriosclerosis. Radiologists need to be aware of the diseases which can exhibit FDG uptake in the vessel wall for proper interpretation.

Visual and semi-quantitative assessment of brain tumors using (201)Tl-SPECT.

OBJECTIVE: To evaluate the usefulness of (201)Tl-SPECT in differentiating benign from malignant brain tumors. METHODS AND MATERIALS: Eighty-eight patients (44 males and 44 females) with 58 high-grade (WHO grade III-IV) and 30 low-grade (WHO grade I-II) tumors were evaluated with (201)Tl-SPECT. (1) Visual assessment was performed by board-certificated radiologists using (201)Tl-SPECT. Tumors were classified in two groups (Tl-positive and Tl-negative) and scored using the five grade evaluation system. Receiver operating characteristic (ROC) analysis was performed in the Tl-positive group. (2) Semi-quantitative assessment involved measurement of early and delayed (201)Tl uptake, and the retention index (RI) was applied as follows: RI=delayed uptake ratio/early uptake ratio. Three combinations of RI using mean and maximum values of the region of interest were calculated. RESULTS: (1) Seventy-four Tl-positive and 14 Tl-negative tumors. The area under the ROC curve (AUC) estimated by three radiologists exceeded a value of 0.7. The value was greater when estimated by the more experienced radiologist. (2) In all RIs, the difference of RI between high-grade tumors and low-grade tumors was statistically significant. CONCLUSION: A visual and semi-quantitative assessment using (201)Tl-SPECT was found to be useful for differentiating benign from malignant brain tumors.

Relationship between FDG uptake and the pathological risk category in gastrointestinal stromal tumors.

PURPOSE: To evaluate (18)F-fluorodeoxyglucose (FDG) uptake and the pathological risk category of gastrointestinal stromal tumors (GISTs), and to investigate the possibility of determining the pathological risk category by positron emission tomography/computed tomography (PET/CT). PATIENTS AND METHODS: We undertook 29 PET/CT studies in 20 patients with GISTs. Eleven of the 20 patients underwent PET/CT prior to therapy, with three of these also undergoing follow-up PET/CT after operation or imatinib therapy. RESULTS: All eleven lesions imaged before treatment were FDG-positive on PET/CT. Seven of these eleven primary lesions were categorized as high risk and the other four primary lesions were categorized as low or intermediate risk. There was a significant difference between the maximum standardized uptake value (SUVmax) of the primary lesions categorized as high risk (11.8±3.15) and that of the primary lesions categorized as low and intermediate risk (2.88±0.47) (p<0.001). Recurrent tumors were also shown as FDG-positive. CONCLUSION: Primary GISTs and recurrent tumors can be detected by PET/CT. Our study suggests that the degree of FDG uptake is a useful indicator of risk category. In addition, PET/CT is probably useful for follow-up examinations of GIST after operation or imatinib therapy. J. Med. Invest. 57: 270-274, August, 2010.

How to manage RI venography in pre-orthopedic surgery patients.

OBJECTIVE: The preoperative evaluation of venous thromboembolism (VTE) is important to avoid complications, because VTE is often induced by orthopedic surgery. We focused on radioisotope venography (RIV) using 99mTc-macroaggregated human serum albumin, examining orthopedic patients. METHODS: We conducted 34 examinations in 33 patients who were referred for RIV and lung perfusion scintigraphy for the pre-orthopedic operative evaluation of VTE. Two board-certified (one nuclear medicine board-certified) radiologists interpreted the images based on the following: (1) flow defect of the lower extremities; (2) interruption of flow; (3) irregular or asymmetric filling of the deep vein (low flow); (4) presence of collateral vessels; and (5) abnormal RI retention on delayed-phase images. Scoring was based on a 5-point scale, and more than 2 points was considered VTE positive. RESULTS: Abnormal findings were noted in 27 of the 34 examinations performed in the 33 patients and normal findings in the other 7 examinations. According to the RI score, 21 patients were classified into the VTE-positive group and 12 into the VTE-negative group. Surgery was canceled because of advanced age and respiratory dysfunction in 2 of the 21 patients in the VTE-positive group. Of the 19 patients who underwent surgery, an IVH filter was placed before surgery in 2 and anticoagulant treatment with heparin and warfarin was initiated on the day of surgery in 12 to prevent postoperative VTE, and only one of the patients receiving anticoagulant treatment developed PTE after surgery. Surgery was canceled due to advanced age and at patient's request in 2 of 12 patients in the VTE-negative group. Anticoagulant treatment with heparin/ warfarin was performed to prevent postoperative VTE in only 3 patients: one with a past medical history of pulmonary infarction, one with atrial fibrillation, and one suspected of having antiphospholipid antibody syndrome. No patient in the VTE-negative group developed VTE after surgery. CONCLUSION: The preoperative identification of patients with VTE by RIV might be useful for perioperative management and the evaluation of preventive measures against postoperative VTE.

Thallium-201 chloride scintigraphy in soft tissue tumors.

OBJECTIVE: We report the findings of Thallium-201 chloride ((201)TlCl) scintigraphy and consider how to use this technique to evaluate the character of soft tissue lesions. PATIENTS AND METHODS: We enrolled 91 consecutive patients (45 males and 46 females, age range 8-91-years-old). Nineteen patients were malignant and 72 were benign. Patients were scanned 15 minutes (early phase) and 3 hours (delayed phase) after (201)TlCl injection. More intense uptake in the lesion compared to the normal side was considered as 'high', the same degree of uptake was considered 'iso', and decreased uptake was 'low'. The retention index (RI) was calculated in 9 patients in the malignant group and in 16 patients in the benign group. RESULTS: In malignant tumors, 15 of 19 patients showed high uptake in both the early and delayed phases. One malignant fibrous histiocytoma patient was high only in the delayed phase and 1 liposarcoma patient was high only in the early phase. Two liposarcoma patients showed an iso uptake in both phases. One of these patients was pathologically diagnosed as a myxoid type. In benign lesions, no lipoma showed increased uptake. All neurogenic tumors except for 2 demonstrated high uptake. All 3 ganglions of the lower extremities showed iso uptake. Most inflammatory diseases showed increased uptake. Clinically-considered benign patients consisted of tumorous lesions or inflammatory disease. Only 2 patients were considered 'low', and these were diagnosed as intramuscular hematoma and cyst. RI was variable in both malignant and benign lesions and no statistically significant difference was seen between malignant and benign lesions by t-test (p=0.72). CONCLUSIONS: A high (201)TlCl uptake lesion is more frequently seen in malignant tumors, but regardless of whether the tumor is benign or malignant, according to the histopathological variety, the (201)TlCl uptake pattern can not be the only indicator to differentiate malignant from benign tumors. We ultimately need to evaluate the nature of tumors by a combination of several imaging techniques.

Is FDG-PET/CT useful for managing malignant pleural mesothelioma?

OBJECTIVE: Imaging techniques such as CT, MRI and PET/CT have essential pre- and post-treatment roles in detecting tumors and evaluating the extension of malignant pleural mesothelioma (MPM). We sough to evaluate the advantages and limitations on FDG-PET/CT findings. PATIENTS AND METHODS: We performed 13 FDG-PET/CT studies in 9 patients with MPM (8 males, 1 female, aged 51 to 84 years, 9 at the initial diagnosis, 4 follow up studies). We reviewed FDG-PET/CT findings of primary tumors, recurrent tumors, lymph nodes, metastasis. RESULTS: All primary and recurrent tumors were FDG positive. The uptake patterns at initial diagnosis were; diffuse+multi-nodular uptake pattern in 5, diffuse irregular thickened uptake pattern in 2, some focal thickened pattern in one, and a slight diffuse uptake pattern in one. Two of the 3 patients diagnosed as N0 by PET and operated on had negative lymph nodes confirmed pathologically. The other patient diagnosed as N0 by PET, who had one month of time lag between PET/CT examination and surgery, was confirmed as N2 by extrapleural pneumonectomy. In 3 patients, hilar or mediastinal lymph nodes were difficult to distinguish from irregular pleural thickening. One patient had a FDG positive lymph node in the ipsilateral supraclavicular region confirmed as metastasis (N3). One patient had a FDG positive lymph node in the para-aortic region. Lung metastasis was seen in one patient (M1). In another patient, two focal nodular uptakes in the colon were detected and confirmed as colon polyps (pathologically Group 3-4). At restaging, 3 of 4 patients showed diffuse+multi-nodular uptake and one patient showed multi-nodular uptake. CONCLUSIONS: The utility of FDG-PET/CT is limited for evaluation of primary tumor extension and nodal status. FDG-PET/CT is useful for detecting distant metastasis and for evaluating activity in supraclavicular or abdominal lymph nodes. It is also useful for identifying unsuspected diseases.

Clear-cell sarcoma of the small intestine detected by FDG-PET/CT during comprehensive examination of an inflammatory reaction.

Clear-cell sarcoma (CCS) is a rare, malignant, soft-tissue tumor, which involves the extremities, particularly the foot and foot joint tendons and aponeuroses. It is morphologically similar to but histochemically distinct from malignant melanoma. CCS arising in the gastrointestinal tract has rarely been reported. The prognosis of CCS is reportedly poor because of the high incidence of metastases at the time of initial diagnosis and the high frequency of recurrence. We report a case of early-stage CCS of the small intestine detected by (18)F-fluoro-2-deoxy D-glucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT) during the comprehensive examination of an inflammatory reaction. In this case, FDG-PET/CT clearly visualized the lesion, which was difficult to detect by contrast CT.

A case of von Recklinghausen's disease with coincident malignant peripheral nerve sheath tumor and gastrointestinal stromal tumor.

(18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET/CT) was performed to evaluate a left femoral subcutaneous mass in a patient with von Recklinghausen's disease (vRd) that gradually enlarged, causing pain and numbness. The left femoral mass showed intense FDG uptake with the maximum standardized uptake value (SUVmax) of 9.0. Other subcutaneous masses considered benign and neurogenic in nature also showed FDG uptake (SUVmax around 3 or less), but the degree of FDG uptake differed considerably from the left femoral mass. This observation suggested that the degree of FDG uptake may be a useful indicator of malignant transformation. Incidentally, PET/CT also showed an asymptomatic large abdominal mass with intense FDG uptake (SUVmax 8.8). The abdominal mass was resected and confirmed as gastrointestinal stromal tumor (GIST) of the small intestine. Three months later, the left femoral mass was operated on and pathologically diagnosed as a malignant peripheral nerve sheath tumor (MPNST). Various malignant diseases are known to occur with high frequency in vRd. Therefore, vRd patients need to have periodical examinations including PET/CT. We present a rare case of a patient with vRd with a MPNST of the left femur and coincidental GIST of the small intestine. February, 2009.