Quantitative Evaluation of 18F-Flutemetamol PET in Patients With Cognitive Impairment and Suspected Alzheimer's Disease: A Multicenter Study

Background: In clinical practice, equivocal findings are inevitable in visual interpretation of whether amyloid positron emission tomography (PET) is positive or negative. It is therefore necessary to establish a more objective quantitative evaluation method for determining the indication for disease-modifying drugs currently under development.

Aims: We aimed to determine cutoffs for positivity in quantitative analysis of ¹⁸F-flutemetamol PET in patients with cognitive impairment and suspected Alzheimer's disease (AD). We also evaluated the clinical efficacy of amyloid PET in the diagnosis of AD. This study was registered in the Japan Registry of Clinical Trials (jRCTs, 031180321).

Methods: Ninety-three patients suspected of having AD underwent ¹⁸F-flutemetamol PET in seven institutions. A PET image for each patient was visually assessed and dichotomously rated as either amyloid-positive or amyloid-negative by two board-certified nuclear medicine physicians. If the two readers obtained different interpretations, the visual rating was rerun until they reached consensus. The PET images were quantitatively analyzed using the standardized uptake value ratio (SUVR) and standardized Centiloid (CL) scale with the whole cerebellum as a reference area.

Results: Visual interpretation obtained 61 positive and 32 negative PET scans. Receiver operating characteristic analysis determined the best agreement of quantitative assessments and visual interpretation of PET scans to have an area under curve of 0.982 at an SUVR of 1.13 and a CL of 16. Using these cutoff values, there was high agreement between the two approaches (kappa = 0.88). Five discordant cases had SUVR and CL values ranging from 1.00 to 1.22 and from 1 to 26, respectively. In these discordant cases, either diffuse or mildly focal elevation of cortical activity confused visual interpretation. The amyloid PET outcome significantly altered the diagnosis of AD (χ² = 51.3, p < 0.0001). PET imaging elevated the proportions of the very high likelihood category from 20.4 to 46.2% and the very low likelihood category from 0 to 22.6%.

Conclusion: Quantitative analysis of amyloid PET using ¹⁸F-flutemetamol can objectively evaluate amyloid positivity using the determined cutoffs for SUVR and CL. Moreover, amyloid PET may have added value over the standard diagnostic workup in dementia patients with cognitive impairment and suspected AD.

Chemical interactions between Saturn’s atmosphere and its rings

The Pioneer and Voyager spacecraft made close-up measurements of Saturn’s ionosphere and upper atmosphere in the 1970s and 1980s that suggested a chemical interaction between the rings and atmosphere. Exploring this interaction provides information on ring composition and the influence on Saturn’s atmosphere from infalling material. The Cassini Ion Neutral Mass Spectrometer sampled in situ the region between the D ring and Saturn during the spacecraft’s Grand Finale phase. We used these measurements to characterize the atmospheric structure and material influx from the rings. The atmospheric He/H2 ratio is 10 to 16%. Volatile compounds from the rings (methane; carbon monoxide and/or molecular nitrogen), as well as larger organic-bearing grains, are flowing inward at a rate of 4800 to 45,000 kilograms per second.

The low-frequency source of Saturn’s kilometric radiation

Understanding how auroral radio emissions are produced by magnetized bodies requires in situ measurements within their source region. Saturn’s kilometric radiation (SKR) has been widely used as a remote proxy of Saturn’s magnetosphere. We present wave and plasma measurements from the Cassini spacecraft during its ring-grazing high-inclination orbits, which passed three times through the high-altitude SKR emission region. Northern dawn-side, narrow-banded radio sources were encountered at frequencies of 10 to 20 kilohertz, within regions of upward currents mapping to the ultraviolet auroral oval. The kilometric waves were produced on the extraordinary mode by the cyclotron maser instability from 6– to 12–kilo–electron volt electron beams and radiated quasi-perpendicularly to the auroral magnetic field lines. The SKR low-frequency sources appear to be strongly controlled by time-variable magnetospheric electron densities.

Titan's ionosphere: A survey of solar EUV influences

Effects of solar EUV on positive ions and heavy negative charge carriers (molecular ions, aerosol, and/or dust) in Titan's ionosphere are studied over the course of almost 12 years, including 78 flybys below 1400 km altitude between TA (October 2004) and T120 (June 2016). The Radio and Plasma Wave Science/Langmuir Probe-measured ion charge densities (normalized by the solar zenith angle) show statistically significant variations with respect to the solar EUV flux. Dayside charge densities increase by a factor of ≈2 from solar minimum to maximum, while nightside charge densities are found to anticorrelate with the EUV flux and decrease by a factor of ≈3-4. The overall EUV dependence of the ion charge densities suggest inapplicability of the idealized Chapman theory below 1200 km in Titan's ionosphere. Nightside charge densities are also found to vary along Titan's orbit, with higher values in the sunward magnetosphere of Saturn compared to the magnetotail.

Ion Trapping by Dust Grains: Simulation Applications to the Enceladus Plume

Using a particle-in-cell electrostatic simulation, we examine the conditions that allow low energy ions, like those produced in the Enceladus plume, to be attracted and trapped within the sheaths of negatively-charged dust grains. The conventional wisdom is that all new ions produced in the Enceladus plume are free to get picked up (i.e., accelerated by the local E-field to then undergo vB acceleration). However, we suggest herein that the presence of submicron charged dust in the plume impedes this pickup process since the local grain electric field greatly exceeds the co-rotation E-fields. The simulations demonstrate that cold ions will tend to accelerate toward the negatively charged grains and become part of the ion plasma sheath. These trapped ions will move with the grains, exiting the plume region at the dust speed. We suggest that Cassini's Langmuir probe is measuring the entire ion population (free and trapped ions), while the Cassini magnetometer detects the magnetic perturbations associated with pickup currents from the smaller population of free ions, with this distinction possibly reconciling the ongoing debate in the literature on the ion density in the plume.

Evaluation of a new motion correction algorithm in PET/CT: combining the entire acquired PET data to create a single three-dimensional motion-corrected PET/CT image

PURPOSE

This study evaluated the potential of Q.Freeze algorithm for reducing motion artifacts, in comparison with ungated imaging (UG) and respiratory-gated imaging (RG).

PATIENTS AND METHODS

Twenty-nine patients with 53 lesions who had undergone RG F-FDG PET/CT were included in this study. Using PET list mode data, five series of PET images [UG, RG, and QF images with an acquisition duration of 3 min (QF3), 5 min (QF5), and 10 min (QF10)] were reconstructed retrospectively. The image quality was evaluated first. Next, quantitative metrics [maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), SD, metabolic tumor volume, signal to noise ratio, or lesion to background ratio] were calculated for the liver, background, and each lesion, and the results were compared across the series.

RESULTS

QF10 and QF5 showed better image quality compared with all other images. SUVmax in the liver, background, and lesions was lower with QF10 and QF5 than with the others, but there were no statistically significant differences in SUVmean and the lesion to background ratios. The SD with UG and RG was significantly higher than that with QF5 and QF10. The metabolic tumor volume in QF3 and QF5 was significantly lower than that in UG.

CONCLUSION

The Q.Freeze algorithm can improve the quality of PET imaging compared with RG and UG.

Beneficial effects through aggressive coronary screening for type 2 diabetes patients with advanced vascular complications

Glycemic control alone does not reduce cardiovascular events in patients with type 2 diabetes (T2D), and routine screening of all T2D patients for asymptomatic coronary artery disease (CAD) is not effective for preventing acute cardiac events. We examined the effectiveness of an aggressive screening protocol for asymptomatic CAD in T2D patients with advanced vascular complications.We designed a 3-year cohort study investigating the effectiveness of the aggressive coronary screening for T2D patients with advanced vascular complications and no known coronary events using propensity score adjusted analysis at a national center in Japan. Eligibility criteria included T2D without known coronary events and with any 1 of the following 4 complications: advanced diabetic retinopathy, advanced chronic kidney disease, peripheral artery disease, or cerebrovascular disease. In the aggressive screening group (n = 122), all patients received stress single photon emission computed tomography and those exhibiting myocardial perfusion abnormalities underwent coronary angiography. In the conventional screening group (n = 108), patients were examined for CAD at the discretion of their medical providers. Primary endpoint was composite outcome of cardiovascular death and nonfatal cardiovascular events.Asymptomatic CAD with ≥70% stenosis was detected in 39.3% of patients completing aggressive screening. The proportions achieving revascularization and receiving intensive medical therapy within 90 days after the screening were significantly higher in the aggressive screening group than in the conventional screening group [19.7% vs 0% (P < 0.001) and 48.4% vs 9.3% (P < 0.001), respectively]. The cumulative rate of primary composite outcome was significantly lower in the aggressive screening group according to a propensity score adjusted Cox proportional hazards model (hazard ratio, 0.35; 95% confidence interval, 0.12-0.96; P = 0.04).Aggressive coronary screening for T2D patients with advanced vascular complications reduced cardiovascular death and nonfatal cardiovascular events.

MAVEN observations of the response of Mars to an interplanetary coronal mass ejection

Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability

The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.

Lesion-based analysis of (18)F-FDG uptake and (111)In-Pentetreotide uptake by neuroendocrine tumors

PURPOSE

To characterize the heterogeneity of metastatic neuroendocrine tumor (NET) lesions, we compared the [(18)F]-fluorodeoxyglucose (FDG) uptake and the (111)In-pentetreotide (SRS) uptake for somatostatin receptor scintigraphy using the CT-based fusion imaging techniques of PET/CT and SPECT/CT.

METHODS

Fifteen consecutive patients with NET lesions were examined using both FDG-PET/CT and SRS SPECT/CT prospectively. A total of 45 metastatic NET lesions were evaluated for FDG uptake according to the standardized uptake value (SUV) and for SRS uptake according to the tumor-to-muscle count ratio (T/M ratio); these values were then compared according to the grade of NET (G), also compared to the tumor volume.

RESULTS

Both the SRS uptake and FDG uptake showed no significant correlation to the tumor volume, and suggested no significant artifacts in these data. The T/M ratio for the SRS uptake ranged from 192.7 to 1.9 and exhibited very wide range of distribution. The SUV for the FDG uptake ranged from 13.8 to 0.77 and exhibited narrow range of distribution. The uptake of the two tracers in individual lesions showed an inverse correlation. The G1 + 2 lesions had a higher SRS uptake than the G3 lesions, but the difference was not significant because of the large variation (40.65 ± 48.03, n = 39 vs. 8.66 ± 13.13, n = 6). However, the G1 + 2 lesions had a significantly lower FDG uptake than the G3 lesions (3.52 ± 1.84, n = 39 vs. 10.82 ± 4.50, n = 6). The tracer uptakes varied largely not only in an inter-subject manner, but also in an intra-subject manner.

CONCLUSION

An inverse correlation between SRS uptake and FDG uptake in the metastatic NET lesions observed in this study may be consistent with the opposing ideas of differentiation and proliferation in oncology. The large variations in SRS and FDG uptake by metastatic NET lesions suggest the biological heterogeneity of advanced NET. These results support the idea that combination therapy targeting both receptor-positive cells and proliferating cells may be beneficial from a functional imaging perspective.

18F-FDG PET/CT findings preceded elevation of serum proteinase 3 antineutrophil cytoplasmic antibodies in Wegener granulomatosis

A 67-year-old woman underwent F-FDG PET/CT after developing a fever of unknown origin. PET/CT revealed intensive FDG uptake at the nasal and lung lesions. On the laboratory data, serum myeloperoxidase antineutrophil cytoplasmic antibodies (ANCA) titer was elevated, although serum directed against proteinase 3 (PR3) ANCA titer was within normal limits. One month after treatment, follow-up PET/CT revealed decreased FDG uptake at the lesions. One year later, serum PR3-ANCA titer elevated, which finally led to a diagnosis of Wegener granulomatosis (WG). WG lesions may be detected earlier by FDG PET/CT than by serum PR3-ANCA titers.

Prognostic value of post-treatment (18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy

OBJECTIVE

To clarify the prognostic value of post-treatment (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with advanced head and neck squamous cell carcinoma (HNSCC) after combined intra-arterial chemotherapy and radiotherapy (IACR).

METHODS

Thirty-six patients with HNSCC who underwent IACR were recruited. The period from the end of IACR to the last post-treatment (18)F-FDG PET/CT examination was 8-12 weeks. Both patient-based and lesion-based analyses were used to evaluate the PET/CT images. For lesion-based analysis, 36 regions (12 lesions of recurrences and 24 scars at primary sites) were selected. The Kaplan-Meier method was used to assess the overall survival (OS) stratified by (18)F-FDG uptake or visual interpretation results.

RESULTS

Twelve patients with recurrence were identified by six months after IACR. The sensitivity and specificity in the patient-based analysis were 67% (8/12) and 88% (21/24), respectively. The mean OS was estimated to be 12.1 months (95% CI, 6.3-18.0 months) for the higher maximum standardized uptake value (SUVmax) group (n=7) and 44.6 months (95% CI, 39.9-49.3 months) for the lower SUVmax group (n=29). OS in the higher SUVmax group (cut-off point, 6.1) or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group (P<0.001 and P<0.05, respectively).

CONCLUSIONS

The SUVmax and visual interpretation of HNSCC on post-IACR (18)F-FDG PET/CT can provide prognostic survival estimates.

A pilot study of 4'-[methyl-11C]-thiothymidine PET/CT for detection of regional lymph node metastasis in non-small cell lung cancer

Background

4′-[methyl-¹¹C]-thiothymidine (4DST) is a novel positron emission tomography (PET) tracer to assess proliferation of malignancy. The diagnostic abilities of 4DST and 2-deoxy-2-¹⁸ F-fluoro-d-glucose (FDG) for detecting regional lymph node (LN) metastases of non-small cell lung cancer (NSCLC) were prospectively compared. In addition, the relationship between the PET result and the patient's prognosis was evaluated.

Methods

A total of 31 patients with NSCLC underwent 4DST PET/computed tomography (CT) and FDG PET/CT. The PET/CT images were evaluated qualitatively and quantitatively for focal uptake of each PET tracer, according to the staging system of the American Joint Committee on Cancer. Surgical and histological results provided the reference standards. Patients were followed for up to two years to assess disease-free survival.

Results

On a per-lesion basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for LN staging were 82%, 72%, 32%, 96%, and 73%, respectively, for 4DST, and 29%, 86%, 25%, 88%, and 78%, respectively, for FDG. The sensitivity of 4DST was significantly higher than that of FDG (P < 0.001). The disease-free survival rate with positive 4DST uptake in nodal lesions was 0.35, which was considerably lower than the rate of 0.83 with negative findings (P = 0.04). Among the factors tested, nodal staging by 4DST was the most influential prognostic factor (P = 0.05) in predicting the presence of a previously existing spread lesion or of a recurrence over the course of 2 years.

Conclusion

4DST PET/CT is sensitive for detecting mediastinal lymph node metastasis in NSCLC, but its low specificity is a limitation. However, it may be helpful in predicting the prognosis of NSCLC.

The utility of FDG-PET/CT and other imaging techniques in the evaluation of IgG4-related disease

OBJECTIVES

This study aimed to evaluate the utility of imaging techniques, including 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), in immunoglobulin (IgG)4-related disease (IgG4-RD).

METHODS

We reviewed eight IgG4-RD patients who were referred to our hospital between August 2006 and April 2012. All cases underwent FDG-PET/CT and brain magnetic resonance imaging (MRI) and endobronchial ultrasonography (EBUS) were also performed in five cases and one case, respectively.

RESULTS

Although nearly all patients with IgG4-RD in this study were negative for CRP (mean 0.22 mg/dL), various organ involvement sites were detected by FDG-PET/CT. In the active phase in two autoimmune pancreatitis (AIP) cases, FDG-PET/CT showed longitudinal and heterogeneous FDG accumulation in the pancreas with FDG uptake in the hilar or mediastinal lymph nodes. Follow-up FDG-PET/CT after therapy in one case revealed that the abnormal FDG uptake in all affected lesions had completely disappeared. In two cases, brain MRI revealed asymptomatic hypertrophic pachymeningitis. In one case, EBUS imaging of mediastinal lymph node swelling was consistent with tortuous vessels with high Doppler signals and hyperechoic strands between lymph nodes.

CONCLUSIONS

When FDG-PET/CT shows FDG accumulation, characteristic of IgG4-RD in organs, without evidence of an associated inflammatory reaction, a diagnosis of IgG4-RD can be made. Treatment effects can be assessed by the disappearance of FDG uptake. A routine brain MRI is useful for detecting asymptomatic hypertrophic pachymeningitis. EBUS may also be useful for differentiating among the etiologies of lymphadenopathy with characteristic sonographic imaging findings.

Long fasting is effective in inhibiting physiological myocardial 18F-FDG uptake and for evaluating active lesions of cardiac sarcoidosis

BACKGROUND

F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a promising modality for detecting active lesions of cardiac sarcoidosis (CS). However, determining whether 18F-FDG uptake in the myocardium is physiological is challenging due to metabolic shift in myocardial cells. Although methods for inhibiting physiological myocardial 18F-FDG uptake have been proposed, no standard methods exist. This study therefore aimed to compare the effect of an 18-h fast (long fasting (LF)) with heparin loading plus a 12-h fast (HEP) before 18F-FDG PET scan.

METHODS

We analyzed the effects of LF and HEP on the inhibition of physiological myocardial 18F-FDG uptake in healthy subjects (18 in HEP and 19 in LF) and in patients with known or suspected CS (96 in HEP and 69 in LF). In CS, the lower uptake of 18F-FDG in the myocardium was evaluated. A visual four-point scale was used to assess myocardial 18F-FDG uptake in comparison with hepatic uptake (1 lower, 2 similar, 3 somewhat higher, 4 noticeably higher).

RESULTS

Myocardial 18F-FDG uptake was 1.68 ± 1.06 in LF and 3.17 ± 1.16 in HEP in healthy subjects (p < 0.0001), whereas it was 1.48 ± 0.99 in LF and 2.48 ± 1.33 in HEP in CS patients (p < 0.0001). Logistic regression and regression trees revealed the LF was the most effective in inhibiting myocardial 18F-FDG uptake. In addition, serum free fatty acid levels on intravenous 18F-FDG injection were a possible biomarker.

CONCLUSIONS

LF is effective in inhibiting myocardial 18F-FDG uptake, and consequently, it could be useful for evaluating active lesions of CS in 18F-FDG PET images.

Visual findings of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with cardiac sarcoidosis

OBJECTIVE

The purpose of this study was to evaluate the cardiac sarcoidosis (CS) activity according to the classified visual uptake pattern using (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and assess the uptake pattern based on the free fatty acid (FFA) levels.

METHODS

Nineteen CS subjects who underwent (18)F-FDG PET/CT examinations with heparin loading (HL) were recruited to evaluate their CS activity. The (18)F-FDG uptake in the heart was classified into five categories ("none," "diffuse" and "diffuse at base," regarded as stable CS, and "focal" and "focal on diffuse," regarded as de novo or worsening CS). The subject data were compared with the (18)F-FDG PET/CT findings in 13 healthy volunteers. The FFA serum levels were assessed in 10 patients with CS and all volunteers.

RESULTS

The sensitivity and specificity of (18)F-FDG PET/CT with HL were 75% (6/8) and 73% (8/11), respectively. The major pattern of cardiac (18)F-FDG uptake was "diffuse at base." Ten of the 32 subjects, including the control group, exhibited this pattern. The FFA serum levels before heparin administration were statistically significantly different between the patients with the "none" pattern and those with the "diffuse" and "diffuse at base" patterns. There were no significant correlations between the FFA serum levels after heparin administration and the (18)F-FDG uptake patterns.

CONCLUSION

"Diffuse at base" is the major (18)F-FDG uptake pattern associated with inadequate physiologic (18)F-FDG suppression. This pattern should be carefully interpreted when examining the (18)F-FDG PET/CT images of CS patients. Additionally, increased FFAs levels associated with HL may not completely suppress the physiologic myocardial FDG uptake.

Re-evaluating the potentials and limitations of (99m)Tc-aprotinin scintigraphy for amyloid imaging

The definitive diagnosis of amyloidosis is made histologically with Congo red stain. Noninvasive imaging techniques for amyloidosis are beneficial for early and definite diagnosis of amyloid deposition in the body. (99m)Tc-aprotinin has the benefit of detecting amyloid deposits mainly in the heart, but it can also detect a wide range of lesions in other locations. The usefulness and limitations of (99m)Tc-Aprotinin scintigraphy for amyloid imaging were re-evaluated based on results from 25 patients (15 men and 10 women; median age, 62.9 y; range, 34-83 y). In addition, other nuclear tracers for imaging amyloidosis are discussed. Of the 25 patients with suspected amyloidosis, 19 patients were proven to have amyloid deposits by histopathological diagnosis. Major (99m)Tc-aprotinin positive sites were confirmed in the myocardium, thyroid, large joints, vertebrae, colon, and lungs. If (99m)Tc-Aprotinin images showed positive findings, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of existing amyloid deposits were 94.7, 33.3, 81.8, and 66.7%, respectively. For analysis based on biopsy region, the sensitivity, specificity, PPV, and NPV of existing amyloid deposition were 30.6, 82.6, 73.3, and 43.2%, respectively. (99m)Tc-Aprotinin has a high potential for diagnosis of amyloid deposition in body; however, due to its physiological uptake, its potential is limited for detection of amyloid deposits in the liver, kidney, and spleen.

14C-Methionine uptake as a potential marker of inflammatory processes after myocardial ischemia and reperfusion

A relationship between l-[methyl-(11)C]methionine ((11)C-methionine) uptake and angiogenesis has been suggested in gliomas. However, methionine uptake in myocardial ischemia and reperfusion has received little attention. We investigated the serial changes and mechanisms of (14)C-methionine uptake in a rat model of myocardial ischemia and reperfusion.

METHODS

The left coronary artery was occluded for 30 min, followed by reperfusion for 1-28 d. At the time of the study, (14)C-methionine (0.74 MBq) and (201)Tl (14.8 MBq) were injected intravenously at 20 and 10 min before sacrifice, respectively. One minute before sacrifice, the left coronary artery was reoccluded, and (99m)Tc-hexakis-2-methoxyisobutylisonitrile (150-180 MBq) was injected to verify the area at risk. Histologic sections of the heart were immunohistochemically analyzed using anti-CD68, anti-smooth-muscle α-actin (SMA), and antitroponin I and compared with the autoradiography findings.

RESULTS

Both (14)C-methionine (uptake ratio, 0.71 ± 0.13) and (201)Tl uptake were reduced in the area at risk at 1 d after reperfusion. However, 3 d after reperfusion, an increased (14)C-methionine uptake (1.79 ± 0.23) was observed corresponding to the area of still-reduced (201)Tl uptake, and the (14)C-methionine uptake gradually declined until 28 d. The increased (14)C-methionine uptake area at 3 and 7 d corresponded well to the macrophage infiltrations demonstrated by positive CD68 staining. Anti-SMA staining appeared at 7 d, after which CD68 staining was gradually replaced by the SMA staining, suggesting that methionine uptake in the early phase after ischemia and reperfusion might reflect inflammatory activity.

CONCLUSION

(14)C-methionine accumulated in the infarcted area, and its uptake corresponded closely to macrophage infiltration at 3-7 d after reperfusion. Methionine imaging may be useful for inflammatory imaging early after myocardial infarction.

Evaluation of Wegener's granulomatosis using 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Objective

Wegener’s granulomatosis (WG) is a relatively rare disease characterized by granulomatous necrotizing vasculitis that primarily involves small- and medium-sized vessels. Systemic findings observed on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) have not been well reported. The purpose of this study was to evaluate the FDG PET/CT imaging in the diagnosis and follow-up of patients with WG.

Materials and methods

Thirteen FDG PET/CT images obtained for 8 patients (2 men and 6 women) with WG were retrospectively analyzed. Of these, 6 were performed for diagnosis, 2 for restaging and follow-up, and 5 for assessment of treatment efficacy. Maximum standardized uptake values (max SUVs) and visual analyses were used to interpret the FDG PET/CT images. In addition, nonenhanced CT findings obtained during FDG PET/CT were described.

Results

WG lesions of the upper respiratory tract and lung were more clearly detected by FDG PET/CT fusion imaging than by nonenhanced CT alone, and all of the active lesions showed decreased FDG uptake after treatment. In addition, FDG PET/CT can provide complementary information to indicate biopsy site based on FDG uptakes.

Conclusions

FDG PET/CT is a feasible modality for evaluating lesion activities, therapeutic monitoring, and follow-up of WG. Furthermore, biopsy sites of WG lesions may be determined by FDG PET/CT.

Similarities and differences in fluorodeoxyglucose positron emission tomography/computed tomography findings in spondyloarthropathy, polymyalgia rheumatica and rheumatoid arthritis

OBJECTIVES

We assessed fluorine-18 ((18)F)-labelled fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) findings in patients with seronegative spondyloarthritis (SpA), polymyalgia rheumatica (PMR), and rheumatoid arthritis (RA).

METHODS

We studied 53 patients with SpA (n=21), PMR (n=16), or RA (n=16) admitted to our hospital between 2006 and 2011. Disease activity in the ischial tuberosities, greater trochanters, spinous processes, vertebral bodies, and sacroiliac joints (SIJ) were evaluated by determining FDG accumulation using maximum standardized uptake values (SUV(max)) and FDG scores.

RESULTS

SUV(max) for ischial tuberosities was significantly higher in PMR than SpA or RA. SUV(max) for greater trochanters and spinous processes was significantly higher in PMR than RA (P<0.001) and significantly higher in SpA than in PMR or RA for SIJ (P=0.01). No significant difference in vertebral scores was observed among groups (P=0.488). FDG scores yielded similar results. X-ray findings were consistent with PET/CT findings in 3/15 (20%) patients with sacroiliitis, whereas magnetic resonance imaging findings were consistent with PET/CT findings in 4/7 (57.1%) patients.

CONCLUSIONS

PET/CT detection of inflammation in the ischial tuberosities, greater trochanters, and spinous processes discriminated between PMR and RA, but not between SpA and PMR. PET/CT findings can distinguish SpA from RA and PMR and are useful for the early diagnosis of sacroiliitis.

Lung amyloid nodule detected by 99mTc-aprotinin scintigraphy

We present a case in which an amyloid lung nodule was diagnosed preoperatively by amyloid scintigraphy (99m)Tc-aprotinin. A 65-year-old man complained of marked weight loss (9 kg) over a period of 6 months. An abnormal shadow in the middle field of the right lung was detected on chest X-ray, corresponding to a 16-mm nodule in the right middle lobe on thoracic computed tomography (CT). Total protein and immunoglobulin G levels were elevated to 8.3 and 2245 mg/dl, respectively, but other blood tests including several tumor marker levels and Cryptococcus antibodies were all within normal range. Fluorodeoxyglucose positron emission tomography showed no uptake by the lung nodule, so lung amyloidosis was considered as differential diagnosis. To avoid risk of bleeding on bronchoscopy, noninvasive amyloid scintigraphy using (99m)Tc-aprotinin was first performed. A nodular, abnormal accumulation was observed in the right middle lung lobe. Diagnostic imaging strongly suggested amyloidosis, so video-assisted thoracic surgery was performed rather than bronchoscopy. Pathological samples showed positive staining with Congo red, and A-λ amyloidosis was diagnosed on the basis of immunostaining. Scintigraphy using (99m)Tc-aprotinin offers a useful, noninvasive method for assessing lung amyloidosis.

4'-[Methyl-11C]-thiothymidine PET/CT for proliferation imaging in non-small cell lung cancer

A new tracer, 4'-[methyl-(11)C]-thiothymidine ((11)C-4DST), has been developed as an in vivo cell proliferation marker based on the DNA incorporation method. This study evaluated the potential of (11)C-4DST PET/CT for imaging proliferation in non-small cell lung cancer (NSCLC), compared with (18)F-FDG PET/CT.

METHODS

Eighteen patients with lung lesions were examined by PET/CT using (11)C-4DST and (18)F-FDG. We constructed decay-corrected time-activity curves of 9 major regions as the mean standardized uptake value. We then compared the maximum standardized uptake value (SUVmax) of lung tumors on both (11)C-4DST and (18)F-FDG PET/CT with the Ki-67 index of cellular proliferation and with CD31-positive vessels as a marker of angiogenesis in surgical pathology.

RESULTS

NSCLC was pathologically confirmed in 19 lesions of 18 patients. Physiologic accumulation of (11)C-4DST was high in liver, kidney, and bone marrow and low in aorta, brain, lung, and myocardium. Biodistribution of (11)C-4DST was almost stable by 20 min after injection of (11)C-4DST. Mean (11)C-4DST SUVmax for lung cancer was 2.9 ± 1.0 (range, 1.5-4.7), significantly different from mean (18)F-FDG SUVmax, which was 6.2 ± 4.5 (range, 0.9-17.3; P < 0.001). The correlation coefficient between SUVmax and Ki-67 index was higher with (11)C-4DST (r = 0.82) than with (18)F-FDG (r = 0.71). The correlation coefficient between SUVmax and CD31 was low with both (11)C-4DST (r = 0.21) and (18)F-FDG (r = 0.21), showing no significant difference between the tracers.

CONCLUSION

A higher correlation with proliferation of lung tumors was seen for (11)C-4DST than for (18)F-FDG. (11)C-4DST PET/CT may allow noninvasive imaging of DNA synthesis in NSCLC.

Asymptomatic coronary heart disease in patients with type 2 diabetes with vascular complications: a cross-sectional study

BACKGROUND

Recent studies have suggested that microvascular and macrovascular diseases are associated with coronary events.

OBJECTIVE

To test the hypothesis that asymptomatic coronary heart disease (CHD) may be present in many patients with diabetes with vascular complications.

DESIGN

From April 2009 to August 2010, the authors conducted a cross-sectional study to assess the prevalence of asymptomatic CHD among patients with type 2 diabetes with vascular complications at a national diabetes centre in Japan. Eligibility criteria included patients with type 2 diabetes with no known CHD and one or more of the following four criteria: (1) proliferative diabetic retinopathy or after photocoagulation; (2) estimated glomerular filtration rate <30 ml/min/1.73 m² or an estimated glomerular filtration rate <45 ml/min/1.73 m² plus albuminuria; (3) peripheral arterial disease; and (4) cerebrovascular disease. Each patient underwent a stress single-photon emission computed tomography; patients with myocardial perfusion abnormalities then underwent coronary angiography.

RESULTS

A total of 1008 patients with type 2 diabetes were screened, and 122 eligible patients consented to participate. Stress single-photon emission computed tomography revealed myocardial perfusion abnormalities in 96 (79%) patients. Of the 112 patients who completed the study protocol, 59 (53%) had asymptomatic CHD with ≥50% diameter stenosis. Additionally, 35 (31%) patients had multivessel disease or left main disease, and 42 (38%) had a coronary artery with ≥75% diameter stenosis. In the multivariate logistic-regression analysis to identify coronary risk factors associated with asymptomatic CHD, the only significant predictor was male sex (OR 6.18; 95% CI 2.30 to 16.64; p<0.001).

CONCLUSIONS

Asymptomatic CHD with ≥50% diameter stenosis and myocardial perfusion abnormalities was detected in more than half of the patients with type 2 diabetes with vascular complications.

Effects of blood glucose level on FDG uptake by liver: a FDG-PET/CT study

In FDG-PET for abdominal malignancy, the liver may be assumed as an internal standard for grading abnormal FDG uptake both in early images and in delayed images. However, physiological variables of FDG uptake by the liver, especially the effects of blood glucose level, have not yet been elucidated.

METHODS

FDG-PET studies of 70 patients examined at 50 to 70 min after injection (60 ± 10 min: early images) and of 68 patients examined at 80 to 100 min after injection (90 ± 10 min: delayed images) were analyzed for liver FDG uptake. Patients having lesions in the liver, spleen and pancreas; patients having bulk tumor in other areas; and patients early after chemotherapy or radiotherapy were excluded; also, patients with blood glucose level over 125 mg/dl were excluded.

RESULTS

Mean standardized uptake value (SUV) of the liver, blood glucose level and sex showed no significant differences between early images and delayed images. However, liver SUV in the delayed image showed a larger variation than that in the early image and showed significant correlation to blood glucose level. The partial correlation coefficient between liver SUV and blood glucose level in the delayed image with adjustment for sex and age was 0.73 (P < .0001). Multivariate regression coefficient (95% confidence interval) of blood glucose was 0.017 (0.013-0.021).

CONCLUSION

Blood glucose level is an important factor affecting the normal liver FDG uptake in nondiabetic patients. In the case of higher glucose level, liver FDG uptake is elevated especially in the delayed image. This may be due to the fact that the liver is the key organ responsible for glucose metabolism through gluconeogenesis and glycogen storage.

Swelling of the prostate gland by permanent brachytherapy may affect seed migration

OBJECTIVE

The purpose was to monitor implanted seeds and to determine factors contributing to seed migration after permanent prostate brachytherapy.

METHODS

Sixty-two consecutive patients with Stage 1 prostate cancer who underwent brachytherapy with (125)I seeds between February 2008 and May 2009 were studied prospectively. On post-operative days 1, 7 and 30, scintigraphy was added to conventional radiography to monitor the migration of the implanted seeds. The prostate volume was measured during the pre-planning stage using ultrasound and during the post-planning stage using computed tomography on post-operative days 0 and 30. Magnetic resonance imaging was performed on day 30.

RESULTS

Of the 4843 seeds implanted in the prostates of 62 patients, 108 seeds (2.2%) in 43 patients (69.4%) exhibited seed migration. Thirty-five seeds could not be identified using any of the imaging modalities and were likely passed during urination (0.7% of the total number of seeds). The maximum number of migrated seeds in one patient was 10 of the 85 implanted seeds. The fraction of patients with seed migration or loss increased from 27.4% on day 1 to 69.4% on day 30. The number of seeds that had migrated from the prostate increased from 48 (0.1% of the total number of seeds) on 1 day to 78 (1.0%) on day 7 and 108 (2.2%) on day 30. Of the seeds lost from the prostate, 38.9% embolized to the lungs. The seed loss during the first post-operative month was closely correlated with the swelling of the prostate gland between the pre-planning measurement and the post-planning measurement performed on day 0 (P < 0.0001).

CONCLUSIONS

Prostate swelling between the pre-planning and post-planning (day 0) measurements was significantly associated with seed migration, and adequate attention should be given to this issue.

18F-FDG PET/CT findings of pharyngeal tuberculosis

A 58-year-old woman with dysphagia and hoarseness underwent 18F-FDG PET/CT to detect the original lesion and disease spread. Bilateral cervical lymphadenopathy and abnormal FDG uptakes in the right tonsil and pharyngeal wall were demonstrated. CT and MRI confirmed the bilateral cervical lymphadenopathy and mucosal thickening in the pharyngeal wall. On the basis of these findings, biopsy sites were selected. Pharyngeal tuberculosis was diagnosed based on culture of the biopsy specimens. 18F-FDG PET/CT contributed to clinical management in this case by detecting tuberculous lesions and showing the extent of these lesions in one examination.

Whole-body FDG-PET/CT on rheumatoid arthritis of large joints

OBJECTIVE

Fluorodeoxyglucose (FDG) uptake in joint lesions in patients with rheumatoid arthritis (RA) reportedly represents the degree of synovial inflammation. Most previous studies have focused on small joints, and the application of whole-body positron emission tomography (PET) combined with computed tomography (CT) (PET/CT) for the evaluation of inflammatory activity in large joints has not been well studied.

METHODS

Eighteen patients with RA underwent FDG-PET/CT. FDG uptake in the knee, hip, carpal, wrist, elbow, shoulder, and atlanto-axial joint (total of 13 joints) and in the axillary lymph nodes was evaluated by calculating the maximum standardized uptake value (SUV(max)) and the visual uptake scores as follows: 0, no uptake; 1, slight uptake; 2, moderate uptake (same as in liver); 3, higher than in liver; 4, highest uptake. The number of painful/swollen joints, the white blood cell (WBC) count, and the C-reactive protein (CRP) level were also evaluated.

RESULTS

Whole-body FDG-PET/CT delineated large-joint lesions in patients with RA, and the metabolic activity of inflammation was accurately overlaid on the joint anatomy. The total FDG score for all 13 joints was significantly correlated with the CRP level (r = 0.653, p < 0.01, n = 18). The total SUV(max) and the CRP level were weakly, but not significantly, correlated (r = 0.377, p > 0.05). The WBC count was not correlated with any other parameter. The mean number of joints per patient with an FDG uptake score of 2 or more was significantly larger than the mean number of painful/swollen joints (6.2 +/- 3.3 vs. 3.1 +/- 2.7, n = 18, p < 0.01) and both parameters were strongly correlated (r = 0.588, p < 0.01, n = 18). Also, FDG uptake score and SUV of painful/swollen joints were significantly higher than these of not painful/swollen joints. FDG uptake was significantly different from patients of remission and patients of active arthritis. Uptake in the atlanto-axial joint was observed in five (mostly asymptomatic) patients (5/18, 28%), and the uptake score was significantly correlated with the total FDG score (r = 0.669, p < 0.01, n = 18). The axillary lymph nodes score was correlated with the arm joints score.

CONCLUSION

FDG-PET/CT represents the inflammatory activity in large joints in patients with RA accurately and sensitively and may be helpful for early evaluations of the extent of RA throughout the whole body including high risk lesion of atlanto-axial joint. Furthermore, the visual FDG uptake score may be useful for evaluating arthritis in large joints.

11C-methionine PET of acute myocardial infarction

Tissue uptake of l-[methyl-(11)C]-methionine ((11)C-methionine) has been used to monitor amino acid metabolism and protein synthesis. We examined whether (11)C-methionine was retained in areas of myocardial infarction after successful reperfusion.

METHODS

Nine patients with infarction in the left anterior descendent region underwent percutaneous transluminal coronary artery intervention within 24 h and (201)Tl SPECT, (18)F-FDG PET, and (11)C-methionine PET within 2 wk of infarction onset. The standardized uptake values of the infarcted area and of the normal area were measured.

RESULTS

The (11)C-methionine images showed increased uptake in the infarcted area, whereas the (201)Tl SPECT and (18)F-FDG PET images showed decreased uptake. The highest accumulation of (11)C-methionine in the infarcted area was observed during the early phase of AMI.

CONCLUSION

(11)C-methionine uptake is elevated in infarcted areas and may reflect the early acute phase of damage healing, that is, the initial process of remodeling.

[Epilepsy in patients with severe motor and intellectual disabilities: a long-term follow-up]

Long-term prognosis of epilepsy was investigated on 117 institutionalized patients with severe motor and intellectual disabilities, who were above 15 years of age in 1977, for a 20-year-period from 1977 to 1997. The incidence of epilepsy was 64.1% (75 patients), which was active in 28 patients (37.3%). The patients with the most severe psychomotor disabilities (bedridden and DQ < 20) showed the highest incidence of epilepsy (85.0%). Patients who died during the follow-up period showed higher incidence of active epilepsy (p < 0.01). During the follow-up of 94 surviving patients, persistence, relapse, and onset of seizures were frequent in patients with most severe intellectual disability, whereas those with less severe intellectual disability (20 < DQ < 35) were all seizure-free. Twenty-one patients had active epilepsy; symptomatic partial epilepsy in 17 (81.0%) and generalized epilepsy in 4 (19.0%). Notably, 5 of the 6 patients with persistent frequent seizures had age-dependent epileptic encephalopathy; persistent Lennox-Gastaut syndrome (LGS) (2 patients), severe epilepsy with multiple independent spike foci evolved from West syndrome (WS) and LGS (2 patients), and partial epilepsy with the history of LGS (1 patient).

Five cases of thrombocytopenia induced by primary human herpesvirus 6 infection

Five patients suffering from exanthem subitum with thrombocytopenia were confirmed as primary human herpesvirus 6 (HHV-6) infection by serological test. All cases had thrombocytopenia during the acute phase of exanthem subitum. The clinical features of these cases were benign, and all recovered without any specific treatment. Moreover, 4 of the 5 cases showed a mild elevation of hepatic transaminase during the same period, and other viral infections including cytomegalovirus, Epstein-Barr virus, and human herpesvirus 7 were ruled out in these patients. It was speculated that direct inhibition of platelet production by the virus or cytokine induced by the virus-infected cells was the mechanism of the thrombocytopenia induced by primary HHV-6 infection.

[T 0 N 2 M 0 small cell lung cancer in a patient with Lambert-Eaton myasthenic syndrome]

We report an unusual case of T 0 N 2 M 0 small cell lung cancer in a patient with Lambert-Eaton myasthenic syndrome (LEMS). A 52-year-old man began to notice muscle weakness in a left limb in January 1996, which was followed by muscle weakness in his left arm and fingers, appetite loss, and general fatigue. An electromyogram (EMG) showed the waxing phenomenon in response to high-frequency repetitive stimulation. Lambest-Eaton myasthenic syndrome was diagnosed, based on his symptoms and EMG findings. Chest computed tomography (CT) was done, and left paratracheal, tracheobronchial, subaortic, and hilar lymphadenopathy were found. No mass was seen in either lung field. Cytologic examination of the sputum and bronchial lavage fluid were done, but no malignant cells were found Small cell lung cancer was diagnosed after thoracoscopic resection of the subaortic lymph nodes. No metastases were detected by bone scintigraphy, abdominal CT, or magnetic resonance imaging of the brain. Complete response and resolution of symptoms were obtained by chemotherapy and irradiation.

[Interstitial pneumonia caused by manidipine HCl]

A 62-year-old woman was given a diagnosis of rheumatoid lung in 1993. She began receiving manidipine HCl (10 mg per day) on June 19, 1996 to treat hypertension. The next day fever, coughing and dyspnea developed. She was admitted to our hospital on June 28. A chest radiograph showed diffuse reticulo-nodular shadows in all lung fields and arterial blood gas analysis revealed severe hypoxemia. Administration of manidipine HCl was stopped and treatment with methylprednisolone was started. The symptoms and the radiographic evidence of infiltrates disappeared. A drug lymphocyte stimulation test for manidipine HCl was positive. We know of no previous report of pneumonia caused by manidipine HCl.

[Long-term follow-up study of children with minimal change nephrotic syndrome]

We conducted a long-term follow-up study of 37 children with biopsy-proved minimal change nephrotic syndrome during a period of over 6 years from onset to adulthood. These patients were classified into 4 groups of 13 infrequent relapsers, 17 frequent relapsers, 3 non-responders and 4 no-relapsers according to the International Study of Kidney Disease in Children (ISKDC). All patients were treated with conventional prednisolone therapy. Two cases of infrequent relapsers, 7 cases of frequent relapsers and 1 case of non responders relapsed in adult life. Two cases of infrequent relapsers and 1 case of frequent relapsers relapsed in adult life after remission for 5 or more years. We concluded that minimal change nephrotic syndromes in childhood should be followed up over a long duration in adult life, evenly in cases with good steroid responsiveness.

[Exercise-induced acute renal failure observed in a boy with idiopathic renal hypouricemia caused by postsecretary reabsorption defect of uric acid]

Acute renal failure without oliguria developed in an 11-year boy after running exercise. With improvement of his renal function, marked hypouricemia became apparent (0.8-0.9 mg/dl). Increased excretion of uric acid into the urine, increased clearance ratio of uric acid against creatinine (CUA/CCr), normal concentration of plasma xanthine and hypoxanthine, and suppression of CUA/CCr ratio by pyrazinamide loading but not by probenecid, were observed in the patient and his two siblings, suggesting that hereditary abnormalities of reabsorption of uric acid after secretion from the renal tubules resulted in the hypouricemia. The mechanism of acute renal failure in this disease remains unknown.