Masashi Nakadate

Is 18F-FDG PET/CT useful for distinguishing between primary thyroid lymphoma and chronic thyroiditis?

Purpose This study aims to investigate the usefulness of 18F-FDG PET/CT for distinguishing between primary thyroid lymphoma (PTL) and chronic thyroiditis. Methods We retrospectively reviewed the data of 196 patients with diffuse 18F-FDG uptake of the thyroid gland and enrolled patients who were diagnosed as having PTL or chronic thyroiditis based on the medical records, pathological findings, and laboratory data. The enrolled patients comprised 10 PTL patients (M/F = 4:6) and 51 chronic thyroiditis patients (M/F = 8:43). Images had been acquired on a PET/CT scanner at 100 minutes after intravenous injection of 18F-FDG. Results The PTL group consisted of 7 patients with diffuse large B-cell lymphoma (DLBCL) and 3 with mucosa-associated lymphoid tissue (MALT) lymphoma. The maximum standardized uptake value (SUVmax) was significantly higher in the PTL group than that in the chronic thyroiditis group (25.3 ± 8.0 and 7.4 ± 3.2, P < 0.001). On the other hand, the CT density (Hounsfield unit: HU) was significantly lower in the PTL group than that in the chronic thyroiditis group (46.1 ± 7.0 HU and 62.1 ± 6.9 HU, P < 0.001). Within the PTL group, the SUVmax was significantly higher in the cases of DLBCL than in those of MALT lymphoma (29.0 ± 6.4 and 16.7 ± 2.3, P = 0.017). Conclusions The SUVmax was significantly higher and the CT density was significantly lower in PTL as compared with those in chronic thyroiditis. Thus, 18F-FDG PET/CT may be useful for distinguishing between PTL and chronic thyroiditis.

Detection of unexpected emergency diseases using FDG-PET/CT in oncology patients

PurposeTo evaluate the frequency of emergency diseases that were detected unexpectedly using FDG-PET/CT.Materials and methodsInterpretation reports for 11,663 FDG-PET/CT studies in our hospital were retrospectively reviewed. Patients with major emergency diseases were extracted according to the following exclusion criteria: (1) relevant findings had been recognized prior to the PET/CT; (2) an intervention or operation that may have been relevant to the present findings was performed within 1 month prior to the PET/CT; and (3) the clinical course could not be investigated sufficiently (e.g., in cases where the patients were introduced from other hospitals).ResultsForty-one patients (0.35%) with unexpected emergency diseases were identified. The most frequent disease was pneumothorax (8 patients), followed by chronic subdural hematoma (CSH) (7 patients), ureteral stone (7 patients), and abdominal aortic aneurysm (AAA) with a dirty fat sign or a high-attenuation crescent sign visualized on CT (4 patients). Nine patients (2 pneumothorax, 3 CSH, 1 cerebral hemorrhage, 1 acute cholecystitis, 1 acute pancreatitis, and 1 acute appendicitis) were hospitalized and/or underwent therapeutic intervention within 1 week after the PET/CT.ConclusionAlthough rare, an unexpected emergency disease requiring urgent management can be detected using FDG-PET/CT in oncology patients.

Pathogenesis and FDG-PET/CT findings of Epstein–Barr virus-related lymphoid neoplasms

Epstein–Barr virus (EBV) is one of the most common viruses, infecting more than 90% of the adult population worldwide. EBV genome is detected in some lymphoid neoplasms. Not only their histopathological subtypes, but also their backgrounds and their clinical courses are variable. A number of B-cell lymphoproliferative disorders associated with the immunocompromised state are related to EBV infection. The incidences of these disorders have been increasing along with generalization of organ transplantations and use of immunosuppressive treatments. Furthermore, some EBV-positive lymphoma can also occur in immunocompetent patients. While evaluating patients with generalized lymphadenopathy of unknown cause by positron emission tomography/computed tomography with 2-deoxy-2-[18F]fluoro-d-glucose (FDG-PET/CT), the possibility of lymphoid neoplasms should be considered in some patients, and a careful review of the background and previous history of the patients is necessary. In this review article, we describe the pathogenesis of EBV-related lymphoid neoplasms and then present FDG-PET/CT images of representative diseases. In addition, we also present a review of other EBV-related diseases, such as infectious mononucleosis and nasopharyngeal carcinoma.

Breast Shape Change Associated with Aging: A Study Using Prone Breast Magnetic Resonance Imaging.

Background: Objective assessments of the shapes of various parts of the body can be made using images acquired with multidetector row computed tomography or magnetic resonance imaging. These images can be useful for understanding the changes in body shape that accompany aging. Methods: Data from our previous bilateral prone breast magnetic resonance imaging studies between March and August 2013 were analyzed. Breast size and volume were measured using these images. All the patients included in the study were divided into a younger group (54 years or younger) and an older group (55 years or older). The values were compared between the 2 groups using paired t tests. Regarding variables that were shown to have a significant difference between the 2 groups, the relationships between age and the values of the variables were evaluated using the Pearson correlation coefficient. Results: A total of 90 breasts, 45 breasts in the younger group and 45 breasts in the older group, were used for analysis. There was a significant correlation between age and craniocaudal nipple deviation (R = −0.38; P < 0.001) and between age and the measured breast volume (R = 0.26; P < 0.05). There was also a significant correlation between the measured breast volume and the craniocaudal nipple deviation (R = −0.48; P < 0.001). Conclusions: A caudal deviation of the nipple and an increase in volume were age-related changes in breast shape. These 2 variables were also correlated.

Optimization of left adrenal vein sampling in primary aldosteronism: Coping with asymmetrical cortisol secretion

We evaluated the influence of catheter sampling position and size on left adrenal venous sampling (AVS) in patients with primary aldosteronism (PA) and analyzed their relationship to cortisol secretion. This retrospective study included 111 patients with a diagnosis of primary aldosteronism who underwent tetracosactide-stimulated AVS. Left AVS was obtained from two catheter positions - the central adrenal vein (CAV) and the common trunk. For common trunk sampling, 5-French catheters were used in 51 patients, and microcatheters were used in 60 patients. Autonomous cortisol secretion was evaluated with a low-dose dexamethasone suppression test in 87 patients. The adrenal/inferior vena cava cortisol concentration ratio [selectivity index (SI)] was significantly lower in samples from the left common trunk than those of the left CAV and right adrenal veins, but this difference was reduced when a microcatheter was used for common trunk sampling. Sample dilution in the common trunk of the left adrenal vein can be decreased by limiting sampling speed with the use of a microcatheter. Meanwhile, there was no significant difference in SI between the left CAV and right adrenal veins. Laterality, determined according to aldosterone/cortisol ratio (A/C ratio) based criteria, showed good reproducibility regardless of sampling position, unlike the absolute aldosterone value based criteria. However, in 11 cases with autonomous cortisol co-secretion, the cortisol hypersecreting side tended to be underestimated when using A/C ratio based criteria. Left CAV sampling enables symmetrical sampling, and may be essential when using absolute aldosterone value based criteria in cases where symmetrical cortisol secretion is uncertain.

Embolosclerotherapy by the Transvenous Approach for Lower Extremity Arteriovenous Malformation in Cowden Syndrome: A Case Report

A 69-year-old female with Cowden syndrome presented with pain at rest in the right leg. Arteriovenous malformations (AVMs) of the right lower extremity were detected by computed tomography and magnetic resonance imaging. Angiography indicated arteriolovenous fistulae, which were initially treated using a transarterial approach with minimal therapeutic effect. In contrast, excellent outcomes were achieved with a transvenous approach using coil embolization and liquid sclerotherapy for the venous component of the nidus. At 15 months after embolosclerotherapy, no angiographic evidence of AVM recurrence was noted. Embolosclerotherapy by the transvenous approach for AVM in Cowden syndrome was a useful therapeutic strategy for arteriolovenous fistulae.

FDG-PET/CT findings of chronic active Epstein–Barr virus infection

Chronic active Epstein–Barr virus infection (CAEBV) is a disorder characterized by sustained or recurrent systemic inflammatory symptoms: fever, liver dysfunction, hepatosplenomegaly, lymphadenopat...

Seventy FDG-PET/CT cases in which nuclear medicine physicians suspected lymphoma: How reliable are we?

Objective(s): To validate the reliability of nuclear medicine physicians in diagnosing lymphoma using positron emission tomography/computed tomography using 2-deoxy-2-[18F]fluoro-D-glucose (FDG-PET/CT) and to determine findings that reliably suggest lymphoma. Methods: Seventy patients suspected of having lymphoma using FDG-PET/CT were enrolled in this retrospective study. Two nuclear medicine physicians read all the interpretation reports and graded the degree of suspicion by consensus (3: definitely suspicious, 2: probably suspicious, and 1: possibly suspicious). The following factors were also investigated for each patient: maximum standardized uptake value (SUVmax) of the lesions, serum level of soluble interleukin-2 receptor (sIL-2R), and the presence of splenic FDG uptake higher than that of the liver. Results: The study group consisted of 34 lymphomas, 18 other malignancies, and 18 benign lesions according to histopathological diagnosis. No patient with a Grade 1 degree of suspicion was diagnosed as lymphoma. SUVmax and the serum level of sIL-2R could not distinguish lymphoma from other diseases. Of the 11 patients who presented with elevated splenic FDG uptake, 10 were diagnosed as having lymphoma. Conclusion: When the degree of suspicion by nuclear medicine physicians is low, the possibility of lymphoma is also low. On the other hand, elevated splenic FDG uptake may suggest lymphoma.

Anterograde Degeneration of the Nigrostriatal Pathway Visualized by 123I-FP-CIT SPECT in a Patient With Artery of Percheron Infarction.

I-FP-CIT SPECT is widely used for diagnosis in patients with parkinsonism. Vascular parkinsonism usually has nonspecific findings from normal uptake to radiotracer decrease in the infarcted region. Infarction of the substantia nigra has been reported as a rare cause of vascular parkinsonism. We present a case of artery of Percheron infarction involving the substantia nigra unilaterally with ipsilateral reduction of striatal uptake on I-FP-CIT SPECT, suggesting anterograde degeneration of the nigrostriatal pathway. Infarction of the substantia nigra should be considered in cases of decreased striatal uptake with marked laterality on I-FP-CIT SPECT.