Recent topics in fibroblast activation protein inhibitor-PET/CT: clinical and pharmacological aspects

Recently, positron emission tomography (PET) with fibroblast activation protein inhibitor (FAPI) has gained significant attention as an advanced tumor diagnostic imaging tool. FAPI PET has a promising potential owing to its ability to accurately depict most malignant tumors. It has an accuracy that is comparable to or surpassing the diagnostic accuracy of PET using 18F-fluorodeoxyglucose (FDG). Moreover, FAPI PET can identify malignant lesions that may be inconclusive on FDG PET. Beyond its application in neoplastic disorders, there have been encouraging reports suggesting the utility of FAPI PET in non-neoplastic conditions such as respiratory or cardiac diseases. This article aimed to provide a comprehensive overview of the recently published articles investigating FAPI and discuss its clinical utility with an emphasis on its application in tumor diagnostics. Numerous radiopharmaceutical FAPIs, including 18F- and 68Ga-labeled compounds, have been developed, and they offer various advantages and applications. With the progress in the FAPI PET synthesis to enhance accumulation and retention in pathological lesions, future studies are expected to provide valuable data on its therapeutic efficacy.

Technical Note: Novel imaging method to obtain gray matter-attenuated inversion recovery image using low-field magnetic resonance imaging systems

INTRODUCTION

The double inversion recovery (DIR) technique suppresses two types of tissue signals with different T1 values by applying two inversion recovery (IR) pulses with different inversion times (TI). In contrast, the double tissue suppression with multi-echo acquisition and single TI combining HIRE (DOMUST-HIRE) method, is a technique enabling the white-matter-attenuated inversion recovery (WAIR) images by setting one inversion time (TI) in a sequence based on the multi-echo method and subtracting the second echo image from the first echo image. Here, we propose a new sequence that can provide the gray-matter-attenuated inversion recovery image based on the DOMUST-HIRE method.

METHODS

In this small clinical study, we performed determination of optimal TI and physical evaluation by imaging a subject's head with T1WI and our proposed method for GAIR images.

RESULTS

Our proposed method could increase the contrast ratio and the contrast-to-noise ratio between white matter (WM) and gray matter (GM), whereas the signal-to-noise ratio WM and GM decreased than with T1WI method.

CONCLUSIONS

Our proposed method can be used to suppress GM and CSF signals.

IMPLICATIONS FOR PRACTICE

The use of our proposed method in low-field MRI systems could provide GAIR image.

Efficacy of Dynamic Chest Radiography for Chronic Thromboembolic Pulmonary Hypertension

Background While current guidelines require lung ventilation-perfusion (V/Q) scanning as the first step to diagnose chronic pulmonary embolism in pulmonary hypertension (PH), its use may be limited by low availability and/or exposure to ionizing radiation. Purpose To compare the performance of dynamic chest radiography (DCR) and lung V/Q scanning for detection of chronic thromboembolic PH (CTEPH). Materials and Methods Patients with PH who underwent DCR and V/Q scanning in the supine position from December 2019 to July 2021 were retrospectively screened. The diagnosis of CTEPH was confirmed with right heart catheterization and invasive pulmonary angiography. Observer tests were conducted to evaluate the diagnostic accuracy of DCR and V/Q scanning. The lungs were divided into six areas (upper, middle, and lower for both) in the anteroposterior image, and the number of lung areas with thromboembolic perfusion defects was scored. Diagnostic performance was compared between DCR and V/Q scanning using the area under the receiver operating characteristic curve. Agreement between the interpretation of DCR and that of V/Q scanning was assessed using the Cohen kappa coefficient and percent agreement. Results A total of 50 patients with PH were analyzed: 29 with CTEPH (mean age, 64 years ± 15 [SD]; 19 women) and 21 without CTEPH (mean age, 61 years ± 22; 14 women). The sensitivity, specificity, and accuracy of DCR were 97%, 86%, and 92%, respectively, and those of V/Q scanning were 100%, 86%, and 94%, respectively. Areas under the receiver operating characteristic curve for DCR and V/Q scanning were 0.92 (95% CI: 0.79, 0.97) and 0.93 (95% CI: 0.78, 0.98). Agreement between the consensus interpretation of DCR and that of V/Q scanning was substantial (κ = 0.79 [95% CI: 0.61, 0.96], percent agreement = 0.9 [95% CI: 0.79, 0.95]). Conclusion Dynamic chest radiography had similar efficacy to ventilation-perfusion scanning in the detection of chronic thromboembolic pulmonary hypertension. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Wandtke and Koproth-Joslin in this issue.

Utility of FDG PET at the Initial Radioiodine Therapy in Differentiated Thyroid Cancer

BACKGROUND/AIM

Differentiated thyroid cancer (DTC) has a good prognosis, except in the case of patients with radioiodine therapy (RIT)-refractory cancer. However, since DTC is essentially a slowly progressing cancer, it is usually judged to be a DTC with a poor prognosis after multiple RITs and yearly follow-up with echo, computed tomography (CT), and serum thyroglobulin values. This study investigated whether fluorodeoxyglucose-positron emission tomography/CT (FDG PET/CT) combined with initial RIT could identify early-stage patients with poor prognosis.

PATIENTS AND METHODS

We evaluated 100 patients with high-risk DTC who underwent total thyroidectomy and received RIT at our institution. We analyzed the clinical outcomes of patients and ¹⁸F-FDG accumulation using univariate and multivariate Cox proportional hazards regression models.

RESULTS

The 10-year overall survival (OS) was 87.9%, with no significant difference in OS between ¹⁸F-FDG accumulation at pre-total or near-total thyroidectomy (NTT) (p=0.180) and ¹³¹I accumulation at initial RIT (p=0.577). However, ¹⁸F-FDG positive patients had a significantly worse prognosis than negative patients (p=0.005) at initial RIT.

CONCLUSION

¹⁸F-FDG PET/CT plays an important role in both the diagnosis and prognostic prediction of RIT refractory disease in DTC patients. ¹⁸F-FDG PET/CT can be a useful tool particularly at the time of initial RIT since the ¹⁸F-FDG accumulation enables the screening of high-risk DTC with poor prognosis at a very early time stage.

A review of harmonization strategies for quantitative PET

PET can reveal in vivo biological processes at the molecular level. PET-derived quantitative values have been used as a surrogate marker for clinical decision-making in numerous clinical studies and trials. However, quantitative values in PET are variable depending on technical, biological, and physical factors. The variability may have a significant impact on a study outcome. Appropriate scanner calibration and quality control, standardization of imaging protocols, and any necessary harmonization strategies are essential to make use of PET as a biomarker with low bias and variability. This review summarizes benefits, limitations, and remaining challenges for harmonization of quantitative PET, including whole-body PET in oncology, brain PET in neurology, PET/MR, and non-¹⁸F PET imaging. This review is expected to facilitate harmonization of quantitative PET and to promote the contribution of PET-derived biomarkers to research and development in medicine.

A deep learning model based on fusion images of chest radiography and X-ray sponge images supports human visual characteristics of retained surgical items detection

PURPOSE

Although a novel deep learning software was proposed using post-processed images obtained by the fusion between X-ray images of normal post-operative radiography and surgical sponge, the association of the retained surgical item detectability with human visual evaluation has not been sufficiently examined. In this study, we investigated the association of retained surgical item detectability between deep learning and human subjective evaluation.

METHODS

A deep learning model was constructed from 2987 training images and 1298 validation images, which were obtained from post-processing of the image fusion between X-ray images of normal post-operative radiography and surgical sponge. Then, another 800 images were used, i.e., 400 with and 400 without surgical sponge. The detection characteristics of retained sponges between the model and a general observer with 10-year clinical experience were analyzed using the receiver operator characteristics.

RESULTS

The following values from the deep learning model and observer were, respectively, derived: Cutoff values of probability were 0.37 and 0.45; areas under the curves were 0.87 and 0.76; sensitivity values were 85% and 61%; and specificity values were 73% and 92%.

CONCLUSION

For the detection of surgical sponges, we concluded that the deep learning model has higher sensitivity, while the human observer has higher specificity. These characteristics indicate that the deep learning system that is complementary to humans could support the clinical workflow in operation rooms for prevention of retained surgical items.

Clinical significance of the combination of preoperative SUVmax and CEA in patients with clinical stage IA lung adenocarcinoma

BACKGROUND

Preoperative maximum standardized uptake value (SUVmax) of 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography and serum carcinoembryonic antigen (CEA) have been reported as prognostic factors for lung adenocarcinoma. However, the significance of combined SUVmax and CEA in early-stage lung adenocarcinoma is not well known.

METHODS

We retrospectively evaluated the relationship between the combination of SUVmax and CEA and the prognosis of 410 patients with clinical stage IA lung adenocarcinoma who underwent resection. The cutoff values for SUVmax and CEA were determined by receiver operating characteristic curve analysis, and patients were categorized into high SC (SUVmax and CEA) group (SUVmax ≥2.96 and CEA ≥5.3), moderate SC group (either SUVmax <2.96 and CEA ≥5.3 or SUVmax ≥2.96 and CEA <5.3) and low SC group (SUVmax <2.96 and CEA <5.3).

RESULTS

Kaplan-Meier curve analysis showed that patients with clinical stage IA lung adenocarcinoma in the high SC group had significantly shorter overall survival (OS) and recurrence-free survival (RFS) than the other groups (p = 0.011 and p < 0.0001, respectively). Multivariate analysis showed that high SC was an independent prognostic factor of OS (p = 0.029) and RFS (p < 0.0001).

CONCLUSIONS

High values of SUVmax and CEA were associated with poor OS and RFS in patients with stage IA lung adenocarcinoma. Simultaneous evaluation of SUVmax and CEA may be an effective prognostic marker to determine the optimal treatment strategy of early-stage lung adenocarcinoma.

Prognostic value of pre-transplantation total metabolic tumor volume on 18fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography in relapsed and refractory aggressive lymphoma

Relapsed and refractory aggressive lymphoma have a poor prognosis. High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) is effective in chemosensitive patients. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is among the few options for non-chemosensitive patients. ¹⁸Fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (¹⁸FDG-PET/CT) is the standard tool for evaluating response to chemotherapy and residual tumor volume. However, accurate assessment of residual tumor volume is not currently being achieved in clinical practice, and its value in prognostic and therapeutic stratification remains unclear. To answer this question, we investigated the efficacy of quantitative indicators, including total metabolic tumor volume (TMTV), in predicting prognosis after auto-HSCT and allo-HSCT. We retrospectively analyzed 39 patients who received auto-HSCT and 28 who received allo-HSCT. In the auto-HSCT group, patients with a higher TMTV had a poor prognosis due to greater risk of relapse. In the allo-HSCT group, patients with a higher TMTV had a lower progression-free survival rate and a significantly higher relapse rate. Neither Deauville score nor other clinical parameters were associated with prognosis in either group. Therefore, pre-transplant TMTV on PET is effective for prognostic prediction and therapeutic decision-making for relapsed or refractory aggressive lymphoma.

Prediction of pathological response to preoperative chemotherapy for pancreatic ductal adenocarcinoma using 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography

AIM

To determine whether the pathological response to preoperative chemotherapy for pancreatic ductal adenocarcinoma (PDAC) can be predicted using 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography (F-18 FDG-PET).

MATERIALS AND METHODS

Twenty-eight patients with PDAC who underwent only neoadjuvant chemotherapy (NAC) before surgery were enrolled in the study. All patients had F-18 FDG-PET examinations before NAC. The resected specimen was pathologically evaluated according to the Classification of Pancreatic Carcinoma (7th edn). Patients were categorised into a non-response group and a response group based on the pathological findings. The non-response group (Grades 1a and 1b) showed ≤50% necrosis in the specimen, while the specimens of the response group (Grades 2-3) showed >50% necrosis. The maximum standardised uptake values (SUVmax) of the tumours on F-18 FDG-PET were measured. The mean values of SUVmax were compared between the two groups. The diagnostic performance of SUVmax in distinguishing the two groups was also evaluated using receiver operating characteristic analysis.

RESULTS

The mean SUVmax of the response group was higher than that of the non-response group (9.00 ± 1.78 versus 4.26 ± 2.35; p<0.001). The optimal cut-off value of SUVmax was 9.28 for distinguishing the two groups. The sensitivity, specificity, and accuracy for the prediction in the response group were 80%, 95.7%, and 92.9%, respectively.

CONCLUSIONS

SUVmax on F-18 FDG-PET may be useful as a biomarker to predict the pathological response to NAC in patients with PDAC.

Continuous bed motion in a silicon photomultiplier-based scanner provides equivalent spatial resolution and image quality in whole body PET images at similar acquisition times using the step-and-shoot method

This study investigated the spatial resolution and image quality of the continuous bed motion (CBM) method in a sensitive silicon photomultiplier (SiPM)-based positron emission tomography (PET)/computed tomography (CT) system compared with the traditional step-and-shoot (SS) method. Methods: Siemens Biograph Vision was used in this study. Data acquisition using the SS method was performed for 3 min per bed. In the CBM method, the bed speed ranged from 0.5 to 3.3 mm/s. The acquisition time equivalent to the SS method was 1.1 mm/s for 2-bed ranges and 0.8 mm/s for seven-bed ranges. The spatial resolution was investigated using 18F point sources and evaluated using the full width at half maximum. Image quality was investigated using a National Electrical Manufacturers Association International Electrotechnical Commission body phantom with six spheres 10-, 13-, 17-, 22-, 28-, and 37-mm inner diameters. The radioactivity concentration ratio of the 18F solution in all spheres and the background was approximately 4:1. The detectability of each sphere was visually evaluated on a five-step score. Image quality was physically evaluated using the noise equivalent count rate (NECphantom), contrast percentage of the 10-mm hot sphere (QH,10mm), background variability percentage (N10mm), and contrast-noise ratio (QH,10mm/N10mm). Results: The spatial resolution was not affected by the difference of acquisition methods and bed speeds. The detectability of the 10-mm sphere with a bed speed of 2.2 mm/s or faster was significantly inferior to that of the SS 2-bed method. In evaluating image quality, no significant difference in the contrast percentage was observed among the acquisition methods and speeds in the CBM method. However, the increasing bed speed in the CBM method increased the N10mm and decreased the NECphantom. When comparing the SS 2-bed method with the CBM method at 0.8 mm/s, no significant differences in all parameters were observed. Conclusion: In a SiPM-based PET/CT scanner, the CBM method provides equivalent spatial resolution and image quality in whole body PET images with same acquisition time using the SS method.

Usefulness of semi-quantitative analysis in 123I metaiodobenzylguanidine SPECT/CT for the differentiation of pheochromocytoma and cortical adenoma

OBJECTIVE

¹²³I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of pheochromocytomas (PHEOs), but some PHEOs are difficult to differentiate from cortical adenoma (CA) or normal adrenal uptake by visual evaluation alone. A new semi-quantitative analysis using ¹²³I MIBG SPECT/CT is thus expected. Herein, we introduce the tumor-to-liver count ratio (T/L) and the tumor-to-muscle count ratio (T/M).

METHODS

We examined the cases of 21 patients with PHEOs (10 males, 11 females; age 24-80, median 61 years) and 23 patients with CA (15 males and 8 females, age 30-78, median 58 years). The visual scoring based on ¹²³I MIBG planar images (planar score) and SPECT images (SPECT score) was used as the conventional evaluation. Using ¹²³I MIBG SPECT/CT findings, we calculated the semi-quantitative values of the count ratio using the maximum or mean count of the tumor and the liver or muscle as the reference organ (T/L_max, T/L_mean, T/M_max and T/M_mean). Each evaluation of the PHEOs and CAs was compared, and the diagnosing performance was evaluated based on an ROC analysis.

RESULTS

The area under curve (AUC) values were as follows: the planar score, 0.833; SPECT score, 0.813; T/L_max, 0.986; T/L_mean, 0.975; T/M_max, 0.955; and T/M_mean, 0.933. The AUC for T/M_max was significantly higher than those of the planar score, and SPECT score by ROC analysis (p < 0.01 each).

CONCLUSION

The semi-quantitative value of ¹²³I MIBG SPECT/CT is more useful than the conventional visual evaluation for differentiating PHEOs from CAs.

Impact of Nuclear Factor Erythroid 2-Related Factor 2 in Hepatocellular Carcinoma: Cancer Metabolism and Immune Status

We examined phosphorylated nuclear factor erythroid 2–related factor 2 (P‐NRF2) expression in surgically resected primary hepatocellular carcinoma (HCC) and investigated the association of P‐NRF2 expression with clinicopathological features and patient outcome. We also evaluated the relationship among NRF2, cancer metabolism, and programmed death ligand 1 (PD‐L1) expression. In this retrospective study, immunohistochemical staining of P‐NRF2 was performed on the samples of 335 patients who underwent hepatic resection for HCC. Tomography/computed tomography using fluorine‐18 fluorodeoxyglucose was performed, and HCC cell lines after NRF2 knockdown were analyzed by array. We also analyzed the expression of PD‐L1 after hypoxia inducible factor 1α (HIF1A) knockdown in NRF2‐overexpressing HCC cell lines. Samples from 121 patients (36.1%) were positive for P‐NRF2. Positive P‐NRF2 expression was significantly associated with high alpha‐fetoprotein (AFP) expression, a high rate of poor differentiation, and microscopic intrahepatic metastasis. In addition, positive P‐NRF2 expression was an independent predictor for recurrence‐free survival and overall survival. NRF2 regulated glucose transporter 1, hexokinase 2, pyruvate kinase isoenzymes L/R, and phosphoglycerate kinase 1 expression and was related to the maximum standardized uptake value. PD‐L1 protein expression levels were increased through hypoxia‐inducible factor 1α after NRF2 overexpression in HCC cells. Conclusions: Our large cohort study revealed that P‐NRF2 expression in cancer cells was associated with clinical outcome in HCC. Additionally, we found that NRF2 was located upstream of cancer metabolism and tumor immunity.

Alveolar soft part sarcoma of the orbit: A case report

Alveolar soft part sarcoma is a rare soft tissue neoplasm that accounts for approximately 1% of all sarcomas and is usually identified in the extremities in adults. The occurrence of alveolar soft part sarcoma in the orbit is extremely rare, estimated at approximately 5% – 15% among all cases of alveolar soft part sarcoma . Here, we present a case of 29-year-old woman with orbital alveolar soft part sarcoma. We describe the magnetic resonance and F-18 2-fluoro-2-deoxy-D-glucose-position emission tomography/computed tomography findings of this case. This young woman had a spindle-shaped mass. A higher signal compared to the extraocular muscle on T1-weighted images, numerous flow voids on T2-weighted images, and intense enhancement could be key findings of this disease.

Functional expression of equilibrative and concentrative nucleoside transporters in alveolar epithelial cells

Equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs) mediate the cellular uptake of nucleosides and nucleobases across the plasma membrane and play important roles in the salvage pathways of nucleotide synthesis. However, information about nucleoside transport systems in the lung alveolar epithelial cells is limited. Therefore, in the present study, we examined the function and expression of nucleoside transporters using primary cultured alveolar type II cells and transdifferentiated type I-like cells. The uptake of uridine, a substrate for ENTs and CNTs, in type II and type I-like cells was time, temperature, and concentration dependent, and was inhibited by other nucleoside transporter substrates such as adenosine. Uridine uptake in both cells was insensitive to nanomolar concentrations of NBMPR, a potent ENT1 inhibitor, while it was inhibited by higher concentrations of NBMPR, suggesting that ENT2, but not ENT1, is involved in uridine uptake in these cells. Additionally, uridine uptake was higher in the presence of Na⁺ than in the absence of Na + and was partially inhibited by a CNT inhibitor phloridzin in these cells, suggesting that CNT is also involved in uridine uptake. In both cells, the mRNA expression of ENT1, ENT2, CNT2, and CNT3 was observed. Finally, the activity of uridine uptake was considerably higher in type II cells than in type I-like cells. In addition, the mRNA expression of ENT2, CNT2, and CNT3, but not ENT1, was lower in type I-like cells than in type II cells. These findings would help understand the functional roles of equilibrative and concentrative nucleoside transporters in alveolar epithelial cells.

Impact of Metabolic Activity in Hepatocellular Carcinoma: Association With Immune Status and Vascular Formation

We evaluated the prognostic value of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in hepatocellular carcinoma (HCC). Their association with programmed death ligand 1 (PD-L1) expression and vascular formation was further investigated. In this retrospective study, using a database of 418 patients who had undergone ¹⁸F-FDG PET/CT before hepatic resection for HCC, immunohistochemical staining of PD-L1, clusters of differentiation (CD) 8, CD68, and CD34 was performed. Patients with a high maximum standardized uptake value (SUVmax) on ¹⁸F-FDG PET/CT showed a significantly worse recurrence-free survival (RFS) (hazard ratio [HR]: 1.500; 95% confidence interval [CI]: 1.088-2.069; P = 0.0133) and overall survival (OS) (HR: 2.259; 95% CI: 1.276-4.000; P = 0.0052) than patients with a low SUVmax. Logistic regression analysis showed that a high SUVmax in HCC was significantly associated with PD-L1-positive expression (odds ratio: 4.407; 95% CI: 2.265-8.575; P < 0.0001). SUVmax values of HCC were associated with intratumoral CD8-positive T-cell counts (P = 0.0044) and CD68-positive macrophage counts (P = 0.0061). Stratification based on SUVmax, PD-L1 expression, and the vessels that encapsulate tumor clusters (VETC) status was also significantly associated with RFS and OS. SUVmax, VETC, and PDL1 expression were independently predictive of survival on multivariable analysis. Conclusion: Our large cohort study showed that a high SUVmax on ¹⁸F-FDG PET/CT is associated with a poor clinical outcome and PD-L1 expression in patients with HCC. Additionally, stratification of patients based on the combination of SUVmax, PD-L1 expression, and the VETC status predicts poor clinical outcome.

Monte Carlo simulation of the acquisition conditions for 177Lu molecular imaging of hepatic tumors

OBJECTIVE

To examine the impact of acquisition time on Lutetium-177 (¹⁷⁷Lu) single-photon emission computed tomography (SPECT) images using Monte Carlo simulation.

METHODS

A gamma camera simulation based on the Monte Carlo method was performed to produce SPECT images. The phantom was modeled on a NEMA IEC BODY phantom including six spheres as tumors. After the administration of 7.4 GBq of ¹⁷⁷Lu, radioactivity concentrations of the tumor/liver at 6, 24, and 72 h after administration were set to 1.85/0.201, 2.12/0.156, and 1.95/0.117 MBq/mL, respectively. In addition, the radioactivity concentrations of the tumor at 72 h after administration varied by 1/2, 1/4, and 1/8 when comparison was made. Acquisition times examined were 1.2, 1.5, 2, 3, 6, and 12 min. To assess the impact of collimators, SPECT data acquired at 72 h after the administration using six collimators of low-energy high-resolution (LEHR), extended low-energy general-purpose (ELEGP), medium-energy, and general-purpose (MEGP-1, MEGP-2, and MEGP-3) and high-energy general-purpose (HEGP) were examined. After prefiltering using a Butterworth filter, projection images were reconstructed using ordered subset expectation maximization. The detected photons were classified into direct rays, scattered rays, penetrating rays, and characteristic X-rays from lead. The image quality was evaluated through visual assessment, and physical assessment of contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR). In this study, the CNR threshold for detectability was assumed to be 5.0.

RESULTS

To compare collimators, the highest sensitivity was observed with ELEGP, followed by LEHR and MEGP-1. The highest ratio of direct ray was also observed in ELEGP followed by MEGP-1. In comparison of the radioactivity concentration ratios of tumor/liver, CRC and CNR were significantly decreased with smaller radioactivity concentration ratios. This effect was greater with larger spheres. According to the visual assessment, the acquisition time of 6, 6, and 3 min or longer was required using ELEGP collimator at 6, 24, and 72 h after administration, respectively. Physical assessment based on CNR and CRC also suggested that 6, 6, and 3 min or longer acquisition time was necessary at 6, 24, and 72 h after administration.

CONCLUSION

¹⁷⁷Lu-SPECT images generated via the Monte Carlo simulation suggested that the recommended acquisition time was 6 min or longer at 6 and 24 h and 3 min or longer at 72 h after administration.

Types of Acid and Drying Method Differently Affect the Chemical Profile of Sodium Caseinate

Background: Sodium caseinate is a rich source of protein and minerals originating from animals. Numerous food and non-food products are made from sodium caseinate. The present study investigated the chemical components (moisture, crude protein, ash, and soluble crude protein) of sodium caseinate prepared by different acids and drying techniques. Methods: A completely randomized factorial design was used by different acids including hydrochloric acid (HCl) and acetic acid, and also drying methods including oven (50 °C for 48 h) and freeze drying (-40 °C for 48 h). In each experimental group, sodium caseinate was obtained for determination of moisture, crude protein, ash, and soluble crude protein. Data were statistically evaluated using an ANOVA in SPSS 18.0. Results: The interaction of both acids and drying methods significantly (p<0.01) affected moisture, crud protein, and ash content. HCl treatment coupled with freeze drying was the best combination, resulting in an appreciably higher content of crude protein (52.90%), moisture (5.38%), and soluble protein (0.85%). Conclusion: The kinds of acid and drying method altered the chemically profile of sodium caseinate. The combination of HCl and freeze drying could be the considered as the best approach, resulting in good chemical characteristics of sodium caseinate.

123I metaiodobenzylguanidine (MIBG) uptake predicts early relapse of neuroblastoma using semi-quantitative SPECT/CT analysis

Objective

¹²³I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of neuroblastoma (NB). MIBG uptake is correlated with norepinephrine transporter expression; hence, it is expected that high-MIBG tumors would be more highly differentiated and have a better prognosis than those with lower expression. We have introduced a method of assessing MIBG accumulation semi-quantitatively using SPECT/CT fusion images. The purpose of this study was to evaluate the relationship of ¹²³I MIBG uptake measured by semi-quantitative values of SPECT/CT and early relapse of NB.

Methods

We studied the cases of 11 patients (5 males and 6 females, age 5–65 months, median age 20 months) with histopathologically proven NB between April 2010 and March 2015. The early-relapse group was defined as patients who had relapsed within 3 years after the first ¹²³I MIBG SPECT/CT exam. Other patients were classified as the delay-relapse group. Uptake of MIBG was evaluated using the count ratio of tumor and muscles. T/Mmax and T/Mmean were defined as follows: T/Mmax = max count of tumor/max count of muscle, T/Mmean = mean count of tumor/mean count of muscle.

Results

The average T/Mmean values of the early-relapse group and delay-relapse group were 2.65 ± 0.58 and 7.66 ± 2.68, respectively. The T/Mmean values of the early-relapse group were significantly lower than those of delay-relapse group (p < 0.05). The average T/Mmax of the early-relapse group and delay-relapse group were 8.86 ± 3.22 and 16.20 ± 1.97, respectively. There was no significant difference in T/Mmax values between the two groups.

Conclusions

Low ¹²³I MIBG uptake using semi-quantitative SPECT/CT analysis was correlated with early relapse of NB.

Muse cells, endogenous reparative pluripotent stem cells, are mobilized into the peripheral blood after percutaneous coronary intervention in patients with coronary artery disease

Background

Multilineage-differentiating stress enduring (Muse) cells, endogenous reparative pluripotent stem cells, are defined as stage-specific embryonic antigen 3+ (SSEA3+) and CD105+ double-positive cells. We previously reported that intravenously injected Muse cells home to the damaged heart and differentiate into cardiomyocytes and vessels, and reduce the infarct size and improve cardiac function in a rabbit model of acute myocardial infarction (AMI) (Circ Res 2018), and that endogenous Muse cells are mobilized into the peripheral blood in the acute phase of patients with AMI, which improve left ventricular (LV) function and attenuate LV remodeling in the chronic phase at 6 months (Circ J 2018). However, whether Muse cells are mobilized into the peripheral blood after percutaneous coronary intervention (PCI) in patients with coronary artery disease.

Methods

Muse cells in the peripheral blood was measured by fluorescence-activated cell sorting (FACS) as SSEA3+ and CD105+ double-positive cells in patients with coronary artery disease with 75% coronary stenosis who underwent PCI (n=18) with a mean age of 73.0±7.2 (14 male and 4 female). Blood samples were collected from the antecubital vein in patients with coronary artery disease before, and 1 and 24 h after PCI. Since the majority of Muse cells were detected in the monocyte area and few Muse cells if any were detected in the lymphocyte area, we counted the Muse cells in the monocyte area by FACS. The number of Muse cells was expressed as cells per 100 μL of blood, as follows: absolute number of Muse cells (/100 μL) = white blood cells (/100 μL) × monocytes (%) × SSEA3+/CD105+ double-positive cells (%).

Results

Typical case of SSEA3+/CD105+ double-positive Muse cells measured by FACS shows that majority of Muse cells exist in the monocyte area (Fig, 1-A). The number of Muse cells in the peripheral blood was significantly greater (p&lt;0.05) at 1 h (58.6±23.8 /100 μL) or 24 h after PCI (69.7±43.1/100 μL) as compared with that before PCI (46.3±19.0/100 μL) (Fig. 1-B).

Conclusion

Muse cells, endogenous pluripotent stem cells, are mobilized into the peripheral circulating blood 1 h and 24 h after PCI in patients with coronary artery disease. Mobilized Muse cells after PCI might be contributing to repair the damaged coronary artery.

Figure 1

Funding Acknowledgement

Type of funding source: None

Diagnostic accuracy for the epileptogenic zone detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT

OBJECTIVES

To examine the utility of FDG-PET/MRI in patients with epilepsy by comparing the diagnostic accuracy of PET/MRI and PET/CT in epileptogenic zone (EZ) detection.

METHODS

This prospective study included 31 patients (17 males, 14 females) who underwent surgical resection for EZ. All patients were first scanned using FDG-PET/CT followed immediately with FDG-PET/MRI. Two series of PET plus standalone MR images were interpreted independently by five board-certified radiologists. A 4-point visual score was used to assess image quality. Sensitivities and visual scores from both PETs and standalone MRI were compared using the McNemar test with Bonferroni correction and Dunn's multiple comparisons test.

RESULTS

The EZs were confirmed histopathologically via resection as hippocampal sclerosis (n = 11, 35.5%), gliosis (n = 8, 25.8%), focal cortical dysplasia (n = 6, 19.4%), and brain tumours (n = 6, 19.4%) including cavernous haemangioma (n = 3), dysembryoplastic neuroepithelial tumour (n = 1), ganglioglioma (n = 1), and polymorphous low-grade neuroepithelial tumour of the young (n = 1). The sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). The visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT, as well as standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3).

CONCLUSIONS

The diagnostic accuracy for the EZ detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT.

KEY POINTS

• Sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). • Visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT and standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). • Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3).

Comparison of 18F-FDG PET/CT and 67Ga-SPECT for the diagnosis of fever of unknown origin: a multicenter prospective study in Japan

OBJECTIVE

The aim of this multicenter prospective study was to compare the sensitivity of ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) with that of ⁶⁷Ga single photon emission computed tomography (SPECT) for the identification of the site of greatest importance for the final diagnosis of the cause of fever of unknown origin (FUO).

METHODS

The study participants consisted of patients with an axillary temperature ≥ 38.0 °C on ≥ 2 occasions within 1 week, with repeated episodes for ≥ 2 weeks prior to providing consent, and whose final diagnosis after undergoing specific examinations, including a chest-to-abdomen CT scan, was uncertain. All the patients underwent FDG-PET/CT imaging first, followed by ⁶⁷Ga-SPECT imaging within 3 days. The results of the FDG-PET/CT and ⁶⁷Ga-SPECT examinations were reviewed by the central image interpretation committee (CIIC), which was blinded to all other clinical information. The sensitivities of FDG-PET/CT and ⁶⁷Ga-SPECT were then evaluated with regard to identifying the site of greatest importance for a final diagnosis of the cause of the fever as decided by the patient's attending physician. The clinical impacts (four grades) of FDG-PET/CT and ⁶⁷Ga-SPECT on the final diagnosis were evaluated.

RESULTS

A total of 149 subjects were enrolled in this study between October 2014 and September 2017. No adverse events were identified among the enrolled subjects. Twenty-one subjects were excluded from the study because of deviations from the study protocol. Among the 128 remaining subjects, a final diagnosis of the disease leading to the appearance of FUO was made for 92 (71.9%) subjects. The final diagnoses in these 92 cases were classified into four groups: noninfectious inflammatory disease (52 cases); infectious disease (31 cases), malignancy (six cases); and other (three cases). These 92 subjects were eligible for inclusion in the study's analysis, but one case did not meet the PET/CT image acquisition criteria; thus, PET/CT results were analyzed for 91 cases. According to the patient-based assessments, the sensitivity of FDG-PET/CT (45%, 95% CI 33.1-58.2%) was significantly higher than that for ⁶⁷Ga-SPECT (25%, 95% CI 15.5-37.5%) (P = 0.0029). The clinical impact of FDG-PET/CT (91%) was also significantly higher than that for ⁶⁷Ga-SPECT (57%, P < 0.001).

CONCLUSIONS

FDG-PET/CT showed a superior sensitivity to ⁶⁷Ga-SPECT for the identification of the site of greatest importance for the final diagnosis of the cause of FUO.

Evaluating and comparing the image quality and quantification accuracy of SiPM-PET/CT and PMT-PET/CT

OBJECTIVE

The aim of this study was to evaluate the image quality and the quantification accuracy of Biograph Vision PET/CT scanner as a SiPM-PET in comparison to the conventional PMT-PET, Biograph mCT PET/CT scanner.

METHODS

This study consisted of a phantom study and a retrospective clinical analysis where patients underwent ¹⁸F-FDG PET/CT in both PET systems. The body phantom of the NEMA IEC with 10-37 mm diameter spheres were filled with an ¹⁸F-FDG solution. The root mean square error (RMSE) of SUV, the detectability of 10-mm sphere, NEC_phantom, the background variability (N_10mm) and the contrast-noise-ratio (Q_H,10 mm/N_10mm) were calculated based on the phantom analysis. We also examined the quality of the acquired clinical images using the NEC_patient, NEC_density, SNR_liver, SUV_liver and SUV_lesion.

RESULTS

In the phantom study on Vision scanner, RMSE was relatively lower when the iteration number was 2, 3 or 4. To satisfy a visual score of 1.5 and the reference range of Q_H,10 mm/N_10mm, a 60-s or longer acquisition was required. Our clinical findings show that NEC_patient averaged 17.4 ± 1.72 Mcounts/m in mCT and 29.1 ± 2.83 Mcounts/m in Vision. Furthermore, NEC_density averaged 0.29 ± 0.05 kcounts/cm³ in mCT and 0.53 ± 0.09 kcounts/cm³ in Vision, respectively, whereas SNR_liver averaged 14.6 ± 3.77% in mCT and 21.3 ± 1.69% in Vision (P = 0.0156), respectively. Finally, SUV_liver averaged 2.82 ± 0.28 and 2.55 ± 0.30, SUV_lesion ranged 1.6-17.6 and 1.9-22.9 in mCT and Vision, respectively.

CONCLUSION

SiPM-PET/CT provides superior image quality and quantification accuracy compared to PMT-PET/CT.

Transport of ribavirin in human myelogenous leukemia cell line K562

The anticancer effect of ribavirin, a purine nucleoside analogue, has been studied using cultured cancer cells such as the human myelogenous leukemia cell line K562. In order to exert its pharmacological effect, ribavirin has to enter cancer cells. However, there is little information concerning the transport mechanism of ribavirin into K562 cells. In this study, therefore, we examined the uptake mechanism of ribavirin in K562 cells. The uptake of ribavirin in K562 cells was time- and temperature-dependent, and was saturable with a Km value of 1.5 mM. Ribavirin uptake was inhibited by nucleosides such as adenosine and uridine, and by inhibitors of equilibrative nucleoside transporter 1 (ENT1) such as S-(4-nitrobenzyl)-6-thioinosine and dipyridamole in a concentration-dependent manner. In addition, the expression of ENT1 mRNA in K562 cells was confirmed by real-time PCR. On the other hand, Na⁺-dependence of ribavirin uptake was not observed, suggesting the involvement of ENT1, but not Na⁺-dependent concentrative nucleoside transporters, in ribavirin uptake in K562 cells. Treatment of K562 cells with sodium butyrate induced erythroid differentiation, but ribavirin uptake activity and sensitivity of the uptake to various inhibitors were not different between native and differentiated K562 cells. These results suggest that ribavirin uptake into K562 cells is mainly mediated by ENT1, which may have a pivotal role in anticancer effect of ribavirin.

Nuclear medicine practice in Japan: a report of the eighth nationwide survey in 2017

OBJECTIVE

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years.

METHODS

The subcommittee sent questionnaires, including the number and category of examinations as well as the kind and dose of the radiopharmaceuticals during the 30 days of June 2017, to all nuclear medicine institutes. The total numbers for the year 2017 were then estimated.

RESULTS

A total of 1132 institutes responded to the survey, including 351 PET centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1332 in total, with 7.0% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 88.2 and 23.6%, respectively. The number of single-photon tracer studies in 2017 was 1.08 million which means a decrease in 5.7% in 5 years and 23.6% in 10 years. All but neurotransmitter system, sentinel lymph node, and liver scintigraphy decreased. Bone scintigraphy was a leading examination (32.3%), followed by myocardial scintigraphy (24.1%) and cerebral perfusion study (18.0%) in order. SPECT studies showed an increase from 47.2% to 63.5%. PET centers have also increased from 295 to 389, as compared to the last survey. The 112 PET centers have installed one or two in-house cyclotrons. PET studies showed 24.5% increase in 5 years, with oncology accounting for 88.9%. ¹⁸F-FDG accounted for 98.2% (630,570 examinations). PET examinations using ¹¹C-methionine have decreased, with 2440 examinations in 2017. PET examinations using ¹³N-NH₃ have been increasing, with 2363 examinations in 2017. The number of PET studies using ¹¹C-PIB was 904. ¹³¹I-radioiodine targeted therapies showed an increase in 5 years (23.1%), including 4487 patients for thyroid cancer. Out-patient thyroid bed ablation therapy with 1,110 MBq of ¹³¹I accounted for 36.6% of cancer patients. The number of admission rooms increased from 135 to 157 in 5 years. The number of ²²³Ra targeted therapies for castration-resistant metastatic prostate cancer was 1194 patients.

CONCLUSIONS

Single-photon examinations showed a continuous tendency toward a decline in the survey. In contrast, the number of hybrid SPECT/CT scanner examinations has increased. PET/CT study and radionuclide targeted therapy have steadily increased.

The severity of obstructive sleep apnea syndrome cannot predict the accumulation of brain amyloid by imaging with [11C]-Pittsburgh compound B PET computed tomography in patients with a normal cognitive function

OBJECTIVE

Disturbed sleep due to obstructive sleep apnea syndrome (OSAS) might accelerate amyloidβ (Aβ) deposition, which can be a crucial factor in Alzheimer's disease. We studied Aβ deposition in untreated OSAS patients with normal cognition.

METHOD

We performed polysomnography (PSG) and Aβ imaging with [¹¹C]-Pittsburgh compound B PET computed tomography (¹¹C-PiB PET CT) in 14 untreated OSAS patients (apnea-hypopnea index: 43.8 ± 26.3/h).

RESULTS

The abnormal accumulation of enhanced ¹¹C-PiB PET was observed only one patient with severe, but not the most severe.

CONCLUSIONS

The OSAS severity alone may not predict Aβ deposition in OSAS patients with normal cognition.

Craniofacial penetration by a wooden stick

INTRODUCTION

Penetrating craniofacial injuries caused by stick-like foreign bodies occur as a result of accidents particularly in children, and often lead to significant morbidity.

CASE SUMMARY

We describe a 5-year-old boy who sustained facial trauma after falling on a wooden stick which penetrated his left cheek. At the initial visit, his vital and neurological signs were normal. However, the stick had penetrated the frontal lobe to a depth of 3cm via the orbital cavity and the anterior skull base. The stick was successfully removed while visualizing the anterior skull base in an endoscopic transethmoidal approach. A follow-up examination one year after the accident demonstrated normal visual acuity and ocular motility, with no diplopia, tearing or pain.

DISCUSSION

Penetrating facial injuries caused by stick-like objects carry a significantly higher risk of serious neurological involvement. Even if penetrating facial injuries sometimes appear trivial, the external injury site is often insufficient to determine the position of the object within the head. Although the cheek is a rare entry site for intracranial injuries, the extent of damage should be assessed fully before attempting removal.

Abstract P2-13-02: Patient-reported outcomes with trastuzumab monotherapy versus trastuzumab plus standard chemotherapy as a postoperative adjuvant therapy in HER2-positive elderly breast cancer patients (RESPECT): A randomized, open-label, phase 3 clinical trial

OBJECTIVE: The RESPECT trial compared 1-year trastuzumab monotherapy with trastuzumab plus standard chemotherapy as a postoperative adjuvant therapy in HER2-positive elderly breast cancer patients. Primary objective of this study was to verify the noninferiority of 1-year trastuzumab monotherapy to trastuzumab plus chemotherapy in terms of disease free survival, and the planned analysis showed that the difference of restricted mean survival time between two groups at 3 years was 0.45 months (reported by Sawaki at ASCO2018). This report assesses the patients-reported outcomes and health-related quality of life (HRQoL).

PATIENTS AND METHODS: The study was done at 99 hospitals in Japan. Elderly women (70 to 80 years old) with HER2-positive, stageI-IIIA invasive breast cancer treated by surgery with clear resection margins were randomly assigned to receive either 1-year trastuzumab or 1-year trastuzumab plus standard chemotherapy, stratified by age, hormone-receptor status, pathological lymph node metastasis and institution. Patients completed questionnaires at baseline, 2 months, 1year, and 3 years after protocol treatment started. The primary outcome was global HRQoL assessed using Functional Assessment of Cancer Therapy-General (FACT-G) total score, and secondary outcomes were chemotherapy-induced peripheral neuropathy (CIPN), instrumental activities of daily living (IADL), anxiety, depression, and subjective happiness. We did the analyses by intention to treat, including patients who completed questionnaires at baseline before start of protocol treatment, and 5point or more change is meaningful in FACT-G total score. This study is registered with ClinicalTrials.gov, NCT01104935.

RESULTS: Between Oct 2009 and Oct 2014, 275 patients were enrolled in the study, of whom 9 patients were excluded: 135 assigned to trastuzumab monotherapy and 131 assigned to trastuzumab plus chemotherapy. We detected significant difference between treatment groups for: clinically meaningful HRQoL deterioration rate at 2 months (31% for trastuzumab monotherapy vs 48% for trastuzumab plus chemotherapy; p=0.016) and at 1year (19% vs 38%; p=0.009), clinically meaningful HRQoL improvement rate at 2 months (38% for trastuzumab monotherapy vs 15% for trastuzumab plus chemotherapy; p&lt;0.01) and at 1year (43% vs 25%; p=0.021), severe sensory CIPN rate at 2months (1.9% for trastuzumab monotherapy vs 14.4% for trastuzumab plus chemotherapy; p=0.001), IADL score at 1year (11.97 for trastuzumab monotherapy vs 11.54 for trastuzumab plus chemotherapy; p&lt;0.042), Hospital Anxiety and Depression Scale score at 2months (8.92 for trastuzumab monotherapy vs 10.79 for trastuzumab plus chemotherapy; p&lt;0.003), and subjective happiness score at 1year (12.8 for trastuzumab monotherapy vs 11.8 for trastuzumab plus chemotherapy; p&lt;0.024).

CONCLUSION: Given the small advantage of adjuvant trastuzumab plus chemotherapy compared to trastuzumab monotherapy for elderly HER-2 positive breast cancer women, decisions about treatment should be informed by the risk for adverse health effects associated with chemotherapy.

Citation Format: Kobayashi K, Taira N, Sawaki M, Sagawa N, Baba S, Saito T, Kawahara T, Hagiwara Y, Uemura Y, Shimozuma K, Ohashi Y, Mukai H. Patient-reported outcomes with trastuzumab monotherapy versus trastuzumab plus standard chemotherapy as a postoperative adjuvant therapy in HER2-positive elderly breast cancer patients (RESPECT): A randomized, open-label, phase 3 clinical trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-13-02.

Abstract P1-11-21: Analysis of cognitive function in elderly HER2-positive breast cancer patients receiving either trastuzumab monotherapy or trastuzumab plus chemotherapy as a postoperative adjuvant treatment: A cognitive function sub-study of a randomized, open-label, phase 3 clinical trial (RESPECT trial)

OBJECTIVE: The effect of trastuzumab(Tmab) or chemotherapy on cognitive function has not been fully understood, especially in elderly breast cancer patients. The RESPECT trial compared 1-year(yr) Tmab monotherapy with Tmab plus standard chemotherapy as adjuvant therapy in elderly patients with HER2-positive breast cancer. The primary objective was to verify the noninferiority of 1-yr Tmab monotherapy compared to Tmab plus chemotherapy in terms of disease-free survival, and the planned analysis showed that the difference of restricted mean survival time between two groups at 3 yrs was 0.45 months (Sawaki at ASCO2018). The goal of this report was to assess the impact of the treatment groups on longitudinal cognitive function.

PATIENTS AND METHODS: The study was performed with patients from 99 hospitals in Japan. Elderly women with HER2-positive, stage I-IIIA invasive breast cancer surgery treated with clear resection margins were randomly assigned to either receive 1-yr Tmab or 1-yr Tmab plus standard chemotherapy. 15 institutions participated in the cognitive sub-study. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) at baseline and at 1 and 3 yrs after treatment. The primary outcome was the amount of change in the MMSE score from the baseline. A linear mixed-effects model was used for comparisons of change in the MMSE score between groups, controlling for time and baseline score. Secondary outcomes were the proportion of both suspected mild dementia (MMSE≤27) and dementia (MMSE≤23) at each time point.

RESULTS: Between October 2009 and October 2014, 275 patients were enrolled in the RESPECT trial, and 57 patients were enrolled in the cognitive function sub-study with 2 patients subsequently excluded. The 55-patient sub-study comprised 29 patients assigned to the Tmab monotherapy group and 26 patients assigned to the Tmab plus chemotherapy group. Primary analysis revealed that change in the MMSE score was not significantly different between the two groups (difference −0.6 at 1 yr and −0.9 at 3 yrs; p=0.136), whereas the baseline score was the only significant factor that had an effect on the amount of change in the MMSE score (p&lt;0.001). The proportions of suspected mild dementia at baseline, and at 1 yr and 3 yrs were 15.4, 32.0, and 41.7% in the Tmab monotherapy group, and 45.8, 17.6, and 28.6% in the Tmab plus chemotherapy group. The proportions of suspected mild dementia at baseline were significantly higher in the Tmab plus chemotherapy group (p=0.04). The proportions of suspected dementia at baseline, and at 1 yr and 3 yrs were 0%, 0%, and 4.2% in the Tmab monotherapy group, and 4.2%, 0%, and 4.8% in the Tmab plus chemotherapy group. There were no significant differences in the proportions of suspected dementia between the treatment groups at each time point.

CONCLUSION: Postoperative chemotherapy for elderly breast cancer patients was considered to have little effect on the onset of dementia during the follow-up period of 3 yrs. Further long-term observation is necessary to obtain a significant conclusion.

Citation Format: Takahashi M, Sawaki M, Hagiwara Y, Uemura Y, Kawahara T, Shimozuma K, Ohashi Y, Saito T, Baba S, Kobayashi K, Mukai H, Taira N. Analysis of cognitive function in elderly HER2-positive breast cancer patients receiving either trastuzumab monotherapy or trastuzumab plus chemotherapy as a postoperative adjuvant treatment: A cognitive function sub-study of a randomized, open-label, phase 3 clinical trial (RESPECT trial) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-11-21.

Abstract P3-06-04: Clonal evolution of non-malignant proliferative lesions into breast cancers

[Introduction] Non-malignant proliferative lesions in the breast have been implicated in the development of invasive breast cancer. Previous studies showed that adjacent atypical proliferative lesions and breast cancers shared common genetic alterations, suggesting that these evolved from the same ancestral cell. However, the clonal structure of atypical proliferative lesions and their clonal dynamics during progression to cancer are poorly understood. In this study, we compared genetic profiles (with and without pathogenic germline mutations) of normal mammary ducts, non-malignant proliferative lesions, and cancer tissues from the same patients to illustrate the clonal evolution of cancer from a non-malignant epithelial cell.

[Methods] Multiple samples were collected from different proliferative lesions within the cancer-borne breast, including invasive cancers, using micro-dissection from formalin-fixed, paraffin-embedded surgical specimens. Somatic mutations and copy number alterations (CNAs) were then evaluated by whole exome sequencing.

[Results] We analyzed a total of 34 samples from 5 premenopausal females carrying estrogen receptor-positive cancers, where the samples were obtained from normal ducts (N = 6), non-atypical (N = 1) and atypical (N = 8) proliferative lesions, and non-invasive (N = 16) and invasive (N = 3) cancers. The number of somatic mutations per sample ranged from 1 to 276 and increased with disease progression, regardless of the germline mutation status. Two cases with bilateral cancers had a pathogenic germline mutation of either BRCA2 or TP53, where no somatic mutations or CNAs were shared by individual proliferative lesions, suggesting multifocal independent cancerous evolutions. By contrast, in the remaining three unilateral cases, no pathogenic germline mutations were detected, but all proliferative lesions, which were separated by a distance of 7-25 mm, shared one or more driver alterations, such as an AKT1 mutation (UID: KU01), concurrent 1q gain and 16q loss (der(1;16)) (UID: KU02), and a GATA3 mutation and der(1;16) (UID: KU03), while harboring private mutations and/or CNAs of their own. The phylogenetic analysis based on the number of shared mutations predicted an early origin of these founder mutations, which frequently predated decades before the onset of cancer.

[Conclusions] Our results suggest that early breast cancer development is shaped by the evolution of multiple precancerous clones. These clones are originated from a common ancestor that acquired a founder mutation long before the onset of cancer, followed by branching evolution of multiple clones that acquired additional driver mutations of their own, from which an invasive cancer ultimately develops. In hereditary cases, this process is thought to be substantially promoted multi-focally from within the entire breasts by a germline mutation shared by all mammary cells, frequently resulting in bilateral and/or multifocal breast cancers. Our findings provide unique insight into the early development of breast cancer.

Citation Format: Nishimura T, Yoshida K, Kawata Y, Takeuchi Y, Kakiuchi N, Shiozawa Y, Aoki K, Hirata M, Kataoka TR, Sakurai T, Baba S, Shiraishi Y, Chiba K, Takeuchi K, Haga H, Miyano S, Toi M, Ogawa S. Clonal evolution of non-malignant proliferative lesions into breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-04.

Prognostic outcome and complications of sentinel lymph node navigation surgery for early-stage cervical cancer

BACKGROUND

To evaluate the prognostic outcome and surgical complications in patients with early-stage cervical cancer who underwent sentinel node navigation surgery (SNNS) for hysterectomy or trachelectomy.

METHODS

A total of 139 patients who underwent SNNS using ^99mTc phytate between 2009 and 2015 were evaluated. No further lymph node dissection was performed when intraoperative analysis of the sentinel lymph nodes (SLNs) was negative for metastasis. We compared the surgical complications between the SNNS group and 67 matched patients who underwent pelvic lymph node dissection (PLND) after SLN mapping between 2003 and 2008. We also examined the clinical outcomes in the SNNS group.

RESULTS

The mean number of detected SLNs was 2.5 per patient. Fourteen of the 139 patients in the SNNS group underwent PLND based on the intraoperative SLN results. The amount of blood loss, the operative time, and the number of perioperative complications were significantly less in the SNNS group than in the matched PLND group. There was no recurrence during a follow-up period ranging from 2 to 88 months (median 40 months) in the SNNS group.

CONCLUSIONS

Using SNNS for early-stage cervical cancer is safe and effective and does not increase the recurrence rate. A future multicenter trial is warranted.

Assessment of collimators in radium-223 imaging with channelized Hotelling observer: a simulation study

OBJECTIVE

Radium-223 (²²³Ra) is used in unsealed radionuclide therapy for metastatic bone tumors. The aim of this study is to apply a computational model observer to ²²³Ra planar images, and to assess the performance of collimators in ²²³Ra imaging.

METHODS

The ²²³Ra planar images were created via an in-house Monte Carlo simulation code using HEXAGON and NAI modules. The phantom was a National Electrical Manufacturers Association body phantom with a hot sphere. The concentration of the background was 55 Bq/mL, and the sphere was approximately 1.5-20 times that of the background concentration. The acquisition time was 10 min. The photopeaks (and the energy window) were 84 (full width of energy window: 20%), 154 (15%), and 270 keV (10%). Each 40 images, with and without hot concentration, were applied to a three-channel difference-of-Gaussian channelized Hotelling observer (CHO), and the signal-to-noise ratio (SNR) of the hot region was calculated. The images were examined using five different collimators: two low-energy general-purpose (LEGP), two medium-energy general-purpose (MEGP), and one high-energy general-purpose (HEGP) collimators.

RESULTS

The SNR value was linearly proportional to the contrast of the hot region for all collimators and energy windows. The images of the 84-keV energy window with the MEGP collimator that have thicker septa and larger holes produced the highest SNR value. The SNR values of two LEGP collimators were approximately half of the MEGP collimators. The HEGP collimator was halfway between the MEGP and LEGP. Similar characteristics were observed for other energy windows (154, 270 keV). The SNR value of images captured via the 270-keV energy window was larger than 154-keV, although the sensitivity of the 270-keV energy window is lower than 154-keV. The results suggested a positive correlation between the SNR value and the fraction of unscattered photons.

CONCLUSIONS

The SNR value of CHO reflected the performance of collimators and was available to assess and quantitatively evaluate the collimator performance in ²²³Ra imaging. The SNR value depends on the magnitudes of unscattered photon count and the fraction of unscattered photon count. Consequently, in this study, MEGP collimators performed better than LEGP and HEGP collimators for ²²³Ra imaging.

High incidence of autoimmune gastritis in patients misdiagnosed with two or more failures of H. pylori eradication

BACKGROUND

Although autoimmune gastritis (AIG) is generally considered relatively rare, we frequently encounter AIG among patients at to our hospital who have experienced at least two episodes of Helicobacter pylori eradication failure.

AIMS

We investigated the incidence of AIG in consecutive patients who consulted our department for H. pylori eradication with reference to eradication history.

METHODS

A total of 404 consecutive patients who visited the H. pylori-specific out-patient unit of our hospital from June 2015 to June 2017 were enrolled. Of these, 137 were treatment-naive, 47 had failed treatment once (single failure), and 220 had failed treatment twice or more (multiple failures) by ¹³ C-UBT. Gastroscopy was performed in all patients. Culture tests of gastric mucosal samples were performed for H. pylori and other bacteria positive for urease activity. Anti-parietal cell antibody (APCA) was measured. Patients with severe atrophy in the gastric corpus and positivity for APCA were diagnosed as having AIG.

RESULTS

A total of 43 patients were diagnosed as having AIG, of whom two were treatment-naive (1.5%, 2/137), 1 failed eradication once (2.1% 1/47), and 40 failed treatment at least twice (18.2%, 40/220). The incidence of AIG was significantly higher in the multiple failure group than in the single failure or treatment-naive groups. Urease-positive bacteria, such as Klebsiella pneumoniae and alpha-streptococcus, were identified in 33 of the 35 AIG patients who underwent culture testing.

CONCLUSION

AIG patients were often misdiagnosed as refractory to eradication therapy, probably because achlorhydria in AIG might allow urease-positive bacteria other than H. pylori to colonise the stomach, causing positive ¹³ C-UBT results.

The Effect of Interim FDG-PET-guided Response-Adapted Therapy in Pediatric Patients with Hodgkin's Lymphoma (HL-14) : Protocol for a Phase II Study

This trial enrolls patients with untreated Hodgkin's lymphoma aged<20 years at diagnosis and examines the effects of omitting radiation therapy if the FDG-positron emission tomography (PET) findings after two completed cycles of combination chemotherapy are negative. It thereby aims to determine whether patients who truly require radiation therapy can be identified by FDG-PET. If so, this modality could be used to omit radiation therapy for all other patients, decreasing the risk of serious long-term complications without affecting survival rates. The outcomes of patients for whom FDG-PET is used to assess early treatment response will also be determined.

Time-of-Flight Information Improved the Detectability of Subcentimeter Spheres Using a Clinical PET/CT Scanner

Recent advancements in clinical PET/CT scanners have improved the detectability of small lesions. However, the ideal reconstruction parameters for detecting small lesions have not yet been sufficiently clarified. The purpose of this study was to investigate the detectability of subcentimeter spheres using a clinical PET/CT scanner. Methods: We used a clinical PET/CT scanner to obtain the data of a National Electrical Manufacturers Association body phantom consisting of 6 small spheres (inner diameters, 4.0, 5.0, 6.2, 7.9, 10, and 37 mm) containing ¹⁸F solution. The background activity was 2.65 kBq/mL, and the sphere-to-background ratio was 8. The PET data obtained for 2 and 120 min were reconstructed using ordered-subsets expectation maximization (OSEM), OSEM + point-spread function (PSF), and OSEM + time-of-flight (TOF) with voxel sizes of 2.04 × 2.04 × 2.00 mm (2-mm voxels) and 4.07 × 4.07 × 3.99 mm (4-mm voxels). A gaussian filter was not used. The image quality was evaluated by visual assessment, as well as by physical assessment of the detectability index and recovery coefficients. Results: According to the visual assessment, the detectability of the spheres improved using TOF and a longer acquisition. Using the OSEM+TOF model, the smallest visually detected spheres were 5 mm in diameter with a 120-min acquisition and 6 mm in diameter with a 2-min acquisition. According to physical assessment, the detectability of spheres 10 mm or smaller using the OSEM+TOF image was superior to that using the OSEM image. In addition, the detectability of each hot sphere and recovery coefficient with 2-mm voxels was superior to that with 4-mm voxels. Although OSEM+PSF images showed less background noise, detectability and the recovery coefficient were not improved for spheres 8 mm or smaller. Conclusion: The TOF model with 2-mm voxels improved the detectability of subcentimeter hot spheres on a clinical PET/CT scanner.

Characteristics of Smoothing Filters to Achieve the Guideline Recommended Positron Emission Tomography Image without Harmonization

Objectives

The aim of this study is to examine the effect of different smoothing filters on the image quality and SUV_max to achieve the guideline recommended positron emission tomography (PET) image without harmonization.

Methods

We used a Biograph mCT PET scanner. A National Electrical Manufacturers Association (NEMA) the International Electrotechnical Commission (IEC) body phantom was filled with ¹⁸F solution with a background activity of 2.65 kBq/mL and a sphere-to-background ratio of 4. PET images obtained with the Biograph mCT PET scanner were reconstructed using the ordered subsets-expectation maximization (OSEM) algorithm with time-of-flight (TOF) models (iteration, 2; subset, 21); smoothing filters including the Gaussian, Butterworth, Hamming, Hann, Parzen, and Shepp-Logan filters with various full width at half maximum (FWHM) values (1-15 mm) were applied. The image quality was physically assessed according to the percent contrast (Q_H,10), background variability (N₁₀), standardized uptake value (SUV), and recovery coefficient (RC). The results were compared with the guideline recommended range proposed by the Japanese Society of Nuclear Medicine and the Japanese Society of Nuclear Medicine Technology. The PET digital phantom was developed from the digital reference object (DRO) of the NEMA IEC body phantom smoothed using a Gaussian filter with a 10-mm FWHM and defined as the reference image. The difference in the SUV between the PET image and the reference image was evaluated according to the root mean squared error (RMSE).

Results

The FWHMs of the Gaussian, Butterworth, Hamming, Hann, Parzen, and Shepp-Logan filters that satisfied the image quality of the FDG-PET/CT standardization guideline criteria were 8-12 mm, 9-11 mm, 9-13 mm, 10-13 mm, 9-11 mm, and 12-15 mm, respectively. The FWHMs of the Gaussian, Butterworth, Hamming, Hann, Parzen, and Shepp-Logan filters that provided the smallest RMSE between the PET images and the 3D digital phantom were 7 mm, 8 mm, 8 mm, 8 mm, 7 mm, and 11 mm, respectively.

Conclusion

The suitable FWHM for image quality or SUV_max depends on the type of smoothing filter that is applied.

Evaluation of the Reconstruction Parameters of Brain Dopamine Transporter SPECT images Obtained by a Fan Beam Collimator: A Comparison with Parallel-hole Collimators

OBJECTIVES

The purpose of this study was to examine the optimal reconstruction parameters for brain dopamine transporter SPECT images obtained with a fan beam collimator and compare the results with those obtained by using parallel-hole collimators.

METHODS

Data acquisition was performed using two SPECT/CT devices, namely a Symbia T6 and an Infinia Hawkeye 4 (device A and B) equipped with fan-beam (camera A-1 and B-1), low- and medium-energy general-purpose (camera A-2 and B-2), and low-energy high-resolution (camera A-3 and B-3) collimators. The SPECT images were reconstructed using filtered back projection (FBP) with Chang's attenuation correction. However, the scatter correction was not performed. A pool phantom and a three-dimensional (3D) brain phantom were filled with ¹²³I solution to examine the reconstruction parameters. The optimal attenuation coefficient was based on the visual assessment of the profile curve, coefficient of variation (CV) [%], and summed difference from the reference activity of the pool phantom. The optimal Butterworth filter for the 3D-brain phantom was also determined based on a visual assessment. The anthropomorphic striatal phantom was filled with ¹²³I solution at striatum-to-background radioactivity ratios of 8, 6, 4, and 3. The specific binding ratio (SBR) of the striatum (calculated by the CT method) was used to compare the results with those of the parallel-hole collimators.

RESULTS

The optimal attenuation coefficients were 0.09, 0.11, 0.05, 0.05, 0.11, and, 0.10 cm^-1 for cameras A-1, A-2, A-3, B-1, B-2, and B-3, respectively. The cutoff frequencies of the Butterworth filter were 0.32, 0.40, and 0.36 cycles/cm for camera A, and 0.46, 0.44, and 0.44 cycles/cm for camera B, respectively. The recovery rates of the SBR_mean with camera A were 51.2%, 49.4%, and 45.6%, respectively. The difference was not statistically significant. The recovery rates of the SBR with camera B were 59.2%, 50.7%, and 50.8%, respectively. Camera B-1 showed significantly high SBR values.

CONCLUSION

As the findings indicated, the optimal reconstruction parameters differed according to the devices and collimators. The fan beam collimator was found to provide promising results with each device.

Value of Intraoperative Cytological and Pathological Sentinel Lymph Node Diagnosis in Fertility-Sparing Trachelectomy for Early-Stage Cervical Cancer

BACKGROUND AND OBJECTIVES

Trachelectomy, a fertility-sparing surgery for early-stage cervical cancer, can be performed only when there is no extrauterine extension present. Therefore, identifying the sentinel lymph nodes (SLNs) and using them to obtain an intraoperative pathologic diagnosis can provide information on the feasibility and safety of trachelectomy. Our aim was to assess the value of an intraoperative SLN diagnosis.

METHODS

We retrospectively analyzed the accuracy of intraoperative imprint cytology and frozen-section examination in 201 patients at our institution in whom trachelectomy was planned.

RESULTS

All patients could be evaluated for SLNs; a total of 610 SLNs were analyzed. Although the specificity of both imprint cytology and frozen-section examination was 100.0%, the sensitivity was only 58.6 and 65.5%, respectively. The diagnostic sensitivity was higher in 2-mm slices along the short axis than on bisection along the longitudinal axis. Imprint cytology correctly diagnosed 2 patients who had false-negative results on frozen section. The nature of the metastatic foci that caused an intraoperative false-negative diagnosis was either micrometastasis or isolated tumor cells.

CONCLUSIONS

The accuracy of intraoperative SLN diagnosis requires improvement, especially when small metastatic foci are present.

Metabolic characteristics of programmed cell death-ligand 1-expressing lung cancer on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography

Programmed cell death‐1 (PD‐1) and programmed cell death‐ligand 1 (PD‐L1) have been identified as novel targets of immunotherapy of lung cancer. In present study, we evaluated the metabolic characteristics of lung cancer by using ¹⁸F‐fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F‐FDG PET/CT) with regard to PD‐L1 protein expression. PD‐L1 protein expression was evaluated by immunohistochemistry with the antibody clone SP142 in 579 surgically resected primary lung cancer patients. Cases with less than 5% tumor membrane staining were considered negative. We examined the association between the frequency of PD‐L1 protein expression and the maximum standardized uptake value (SUVmax) in preoperative ¹⁸F‐FDG PET/CT. The cut‐off values for SUVmax were determined by receiver operating characteristic curve analyses. The SUVmax was significantly higher in nonsmall cell lung cancer (NSCLC) patients with PD‐L1 protein expression compared with those without PD‐L1 protein expression (P < 0.0001). However, there was no correlation between SUVmax and PD‐L1 protein expression in patients with neuroendocrine tumors (P = 0.6545). Multivariate analysis revealed that smoking, the presence of pleural invasion, and high SUVmax were independent predictors of PD‐L1 positivity. PD‐L1‐expressing NSCLC had a high glucose metabolism. The SUVmax in preoperative ¹⁸F‐FDG PET/CT was a predictor of PD‐L1 protein expression in patients with NSCLC.

Reliability of the SF-36 in Japanese patients with systemic lupus erythematosus and its associations with disease activity and damage: a two-consecutive year prospective study

We aimed to validate the reliability of the Medical Outcomes Study Short Form-36 (SF-36) among Japanese patients with systemic lupus erythematosus (SLE). Japanese patients with SLE ( n = 233) completed the SF-36 and other related demographic questionnaires, and physicians simultaneously completed the SLE Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus International Collaborating Clinics Damage Index (SDI). Patients were prospectively followed for a repeat assessment the following year. The SF-36 subscales demonstrated acceptable internal consistency (Cronbach’s α of 0.85–0.89), and an overall good test–retest reliability (intraclass correlation coefficient >0.70). The average baseline SF-36 subscale/summary scores except for “bodily pain” were significantly lower than those of the Japanese general population ( p < 0.05). The SDI showed an inverse correlation with the SF-36 subscale/summary scores except for “vitality” and “mental component summary” at baseline, whereas the SLEDAI-2K did not. In the second year, “social functioning” and “mental component summary” of the SF-36 deteriorated among patients whose SDI or SLEDAI-2K score increased (effect sizes < −0.20). In conclusion, the SF-36 demonstrated acceptable reliability among Japanese patients with SLE. Health-related quality of life measured by the SF-36 was reduced in Japanese patients with SLE and associated with disease damage, rather than disease activity.

Metabolic Tumor Volume by 18F-FDG PET/CT Can Predict the Clinical Outcome of Primary Malignant Spine/Spinal Tumors

BACKGROUND AND PURPOSE

Primary malignant spine/spinal tumors (PMSTs) are rare and life-threatening diseases. In this study, we demonstrated the advantage of volume-based 18F-FDG PET/CT metabolic parameter, metabolic tumor volume (MTV), for assessing the aggressiveness of PMSTs.

MATERIALS AND METHODS

We retrospectively reviewed 27 patients with PMSTs and calculated SUVmax, MTV, and total lesion glycolysis (TLG) to compare their accuracy in predicting progression-free survival (PFS) and overall survival (OS) by receiver operating characteristic (ROC) curve analysis. Univariate and multivariate analyses were used to compare the reliability of the metabolic parameters and various clinical factors.

RESULTS

MTV exhibited greater accuracy than SUVmax or TLG. The cut-off values for PFS and OS derived from the AUC data were MTV 45 ml and 83 ml and TLG 250 SUV⁎ml and 257 SUV⁎ml, respectively. MTV above cut-off value, but not TLG, was identified as significant prognostic factor for PFS by log-lank test (p = 0.04). In addition, MTV was the only significant predictive factors for PFS and OS in the multivariate analysis.

CONCLUSIONS

MTV was a more accurate predictor of PFS and OS in PMSTs compared to TLG or SUVmax and helped decision-making for guiding rational treatment options.

A Functional Scoring System Based on Salivary Gland Scintigraphy for Evaluating Salivary Gland Dysfunction Secondary to 131I therapy in Patients with Differentiated Thyroid Carcinoma

INTRODUCTION

Radioiodine therapy with ¹³¹I (¹³¹I therapy) after total or near-total thyroidectomy has been established as an effective treatment for Differentiated Thyroid Carcinoma (DTC), but can induce dry mouth symptoms by salivary gland damage and impair the patients' quality of life.

AIM

To propose a functional scoring system based on Salivary Gland Scintigraphy (SGS) findings that evaluates development of salivary gland dysfunction secondary to ¹³¹I therapy in patients with DTC.

MATERIALS AND METHODS

This retrospective study evaluated the records of 279 DTC patients who underwent SGS after one or more round(s) of ¹³¹I therapy, using 370 MBqof ^99mTc-pertechnetate. The SGS results were assessed using a novel functional scoring system in the Parotid Glands (PGs) and Submandibular Glands (SMGs) according to visual evaluations based on a three-point uptake score, Washout Rate (%WR) score after lemon-juice stimulation, and functional score. The scores were compared among pre treatment, low-dose (<10 GBq), and high-dose (>10 GBq) groups and among pre treatment, symptom-positive, and symptom-negative groups. Risk factors for dry mouth were analyzed by univariate and multivariate logistic regression analyses.

RESULTS

Dry mouth symptoms developed in 15.4% of the DTC patients after ¹³¹I therapy. The three-point uptake, %WR, and functional scores in both the PG and SMG were statistically significant between low-dose and high-dose groups, and between symptom-positive and symptom-negative groups. The PG/SMG functional scores were independent risk factors for dry mouth (odds ratio, 0.03 and 0.0007 respectively).

CONCLUSION

SGS-based PG and SMG functional scores were effective biomarkers to objectively evaluate salivary gland dysfunction, with the high strength of association with dry mouth symptoms.

Detection of bone defects around zirconium component after total knee arthroplasty

BACKGROUND

It is difficult to detect bone defects caused by loosening or osteolysis around the femoral component after total knee arthroplasty (TKA) because the thick metal hinders visualization of bone defects. Previous reports have shown that tomosynthesis, a novel tomographic technique, is advantageous over fluoroscopically guided plain radiography, computed tomography (CT) and magnetic resonance imaging (MRI) for the early detection of bone defects around a conventional cobalt-chromium alloy component. However, there have been no reports on a zirconium component. The purpose of this study was to examine the sensitivity and specificity of the detection of bone defects around a zirconium component using fluoroscopically guided plain radiography, tomosynthesis, CT and MRI.

METHODS

Six zirconium femoral components were implanted in pig knees. Two were cemented without any bone defects. Two were cemented with cystic defects. Two were cemented with four-millimeter-thick defects between the bone cement and the bone. Defects were filled with agarose gel. Eight orthopedic surgeons examined the fluoroscopically guided plain radiography, tomosynthesis, CT and MRI images. Sensitivity and specificity of each method were analyzed.

RESULTS

No bone defects were detected with plain radiography. The sensitivity and specificity of tomosynthesis were 21.9% and 36.8%, respectively. The sensitivity and specificity of CT were 15.1% and 33.0%, respectively. The sensitivity and specificity of MRI were 84.4% and 86.6%, respectively.

CONCLUSIONS

For the detection of bone defects around a zirconium component after TKA, MRI is advantageous over fluoroscopically guided plain radiography, tomography and CT, in terms of sensitivity and specificity.