Oil blotting paper for formalin fixation increases endoscopic ultrasound-guided tissue acquisition-collected sample volumes on glass slides

OBJECTIVES

Endoscopic ultrasound-guided tissue acquisition (EUS-TA) is used for pathological diagnosis and obtaining samples for molecular testing, facilitating the initiation of targeted therapies in patients with pancreatic cancer. However, samples obtained via EUS-TA are often insufficient, requiring more efforts to improve sampling adequacy for molecular testing. Therefore, this study investigated the use of oil blotting paper for formalin fixation of samples obtained via EUS-TA.

METHODS

This prospective study enrolled 42 patients who underwent EUS-TA for pancreatic cancer between September 2020 and February 2022 at the Osaka International Cancer Institute. After a portion of each sample obtained via EUS-TA was separated for routine histological evaluation, the residual samples were divided into filter paper and oil blotting paper groups for analysis. Accordingly, filter paper and oil blotting paper were used for the formalin fixation process. The total tissue, nuclear, and cytoplasm areas of each sample were quantitatively evaluated using virtual slides, and the specimen volume and histological diagnosis of each sample were evaluated by an expert pathologist.

RESULTS

All cases were cytologically diagnosed as adenocarcinoma. The area ratios of the total tissue, nuclear, and cytoplasmic portions were significantly larger in the oil blotting paper group than in the filter paper group. The frequency of cases with large amount of tumor cells was significantly higher in the oil blotting paper group (33.3%) than in the filter paper group (11.9%) (p = 0.035).

CONCLUSIONS

Oil blotting paper can increase the sample volume obtained via EUS-TA on glass slides and improve sampling adequacy for molecular testing.

Immunoreactivity of TTF-1, GATA-3, CEA, and p16/Ki67 cocktail in Cellprep®-processed control samples: Comparison of long-term storage in vials and slides

INTRODUCTION

Cellprep® (CP) is a novel liquid-based cytology (LBC) system. This study aimed to assess the immunoreactivity of control samples stored long-term under two storage conditions using CP.

METHODS

The immunoreactivity in control samples was evaluated under two sample storage conditions: CP vial storage at room temperature (RT: 20-25°C) and CP slide storage in a refrigerator (2-6°C). Clinical samples as controls (total: positive/negative) were immunostained using thyroid transcription factor-1 (TTF-1) (20: 14/6), GATA binding protein 3 (GATA-3) (13: 10/3), carcinoembryonic antigen (CEA) (23: 15/8), and the p16/Ki67 cocktail (20: 12/8) markers. The first immunocytochemistry (ICC) was performed within 1 month using CP vials stored at RT. Samples stored in CP vials and on CP slides were used for the second (within 3-6 months) and third (within 6-11 months) ICCs. Compared with the first ICC, the concordance of immunoreactivity for the second and third ICCs was evaluated using the weighted kappa coefficient.

RESULTS

For TTF-1, CEA, and the p16/Ki67 cocktail markers, ICC controls had stable immunoreactivity for a minimum of 6 months when samples were stored in CP vials (kappa coefficients >0.8), whereas for GATA-3, they were for 3 months. On CP slides, only for the p16/Ki67 cocktail, ICC controls had stable immunoreactivity for at least 3 months (kappa coefficient >0.8).

CONCLUSION

Clinical samples as ICC controls revealed consistently more stable immunoreactivity in CP vials than on CP slides for TTF-1, GATA-3, CEA, and the p16/Ki67 cocktail markers.

Utility of needle biopsy in centrally located lung cancer for genome analysis: a retrospective cohort study

BACKGROUND

It is essential to collect a sufficient amount of tumor tissue for successful next-generation sequencing (NGS) analysis. In this study, we investigated the clinical risk factors for avoiding re-biopsy for NGS analysis (re-genome biopsy) in cases where a sufficient amount of tumor tissue could not be collected by bronchoscopy.

METHODS

We investigated the association between clinical factors and the risk of re-genome biopsy in patients who underwent transbronchial biopsy (TBB) or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) and required re-genome biopsy in cases enrolled in LC-SCRUM Asia, a prospective nationwide genome screening project in Japan. We also examined whether the frequency of re-genome biopsy decreased between the first and second halves of the enrolment period.

RESULTS

Of the 572 eligible patients, 236 underwent TBB, and 134 underwent EBUS-TBNA. Twenty-four TBBs required re-genome biopsy, and multivariate analysis showed that the risk of re-genome biopsy was significantly increased in lesions where the tumor lesion was centrally located. In these cases, EBUS-TBNA should be utilized even if the lesion is a pulmonary lesion. However, it should be noted that even with EBUS-TBNA, lung field lesions are at a higher risk of re-canalization than mediastinal lymph node lesions. It was also found that even when tumor cells were detected in rapid on-site evaluation, a sufficient amount of tumor tissue was not always collected.

CONCLUSIONS

For centrally located pulmonary mass lesions, EBUS-TBNA, rather than TBB, can be used to obtain tumor tissues that can be analyzed by NGS.

Sensitivity of cytology in liver tumor biopsy and its significance in the prompt clinical diagnosis of non-hepatocellular carcinoma

BACKGROUND

Cytology is a fast and simple modality for identifying malignancies and tumor histology. In this study, we analyzed the sensitivity of cytology for liver tumor biopsy and evaluated its potential for prompt clinical diagnosis.

METHODS

This retrospective study included patients who had concurrently undergone conventional cytology, on-site cytology, and histopathology for ultrasound-guided liver tumor biopsies. In the case of malignant tumors, malignancy was first diagnosed, then preliminary clinical diagnosis was established using histology based on cytology and clinical information, followed by histopathological diagnosis. Sensitivity of malignancy detection was evaluated by comparison with histopathological diagnosis.

RESULTS

Of the 191 tumors, 164 (85.9%) were malignant. The sensitivity of conventional cytology for malignancy detection was 97.6%. The sensitivity of non-hepatocellular carcinoma (non-HCC) (99.3%) detection was higher than that of the HCCs (87.5%; p = 0.001). The sensitivity of on-site cytology for malignancy detection was as high as that of conventional cytology. Similar to conventional cytology, the sensitivity of on-site cytology for non-HCC detection (99.3%) was higher than that for HCCs (79.2%; p < 0.001). In most cases of non-HCC tumors (126/140, 90.0%), accurate preliminary clinical diagnoses were obtained by combining on-site cytology with clinical information.

CONCLUSION

Cytology of liver tumor biopsy has high sensitivity for malignancy, especially in non-HCC tumors. On-site cytology can contribute to the prompt clinical diagnosis of non-HCC tumors when combined with clinical information. This approach may be a reassuring modality for patients with severely advanced cancers requiring prompt clinical diagnosis and quick initiation of treatment owing to their deteriorating health.

Usefulness of on-site cytology of liver tumor biopsy in specimen sampling for cancer genomic profiling test

AIM

Appropriate sample selection with a tumor fraction ≥20% without necrosis contamination is required for successful cancer genomic profiling (CGP). Rapid on-site evaluation (ROSE) is performed to assess adequate sampling.

METHOD

This retrospective study included 54 patients who underwent CGP using liver tumor biopsy specimen with ROSE.

RESULT

The sampling success rate (98.1%) was higher than the previously reported 77.5%-88.9%. ROSE was performed once in 51 patients and twice in three patients; for those undergoing ROSE twice, the first ROSE was negative for malignancy, or showed few tumor cells with necrotic cell contamination, while the second ROSE obtained from another location showed abundant malignant cells. In these patients, the CGP was successful using the second specimen, though the first sample did not meet the required criteria for CGP test.

CONCLUSION

Performing ROSE during liver tumor biopsy may be useful for CGP test sampling because ROSE prevents sampling errors and contributes to adequate sampling.

Boring biopsy with rapid on-site evaluation for gastric gastrointestinal stromal tumor: A pilot study

One of 4 patients (25%) and 2 of 3 patients (67%) were correctly diagnosed by conventional and hot boring biopsies, respectively. The median procedure time of conventional and hot boring biopsies was 21 (range, 13-33) and 17 (range, 16-23) min, respectively. Rapid on-site evaluation was performed totally 12 times in 7 patients. The positive and negative predictive values of rapid on-site evaluation for gastrointestinal stromal tumor were 0.5 (0.12-0.88) and 1.0 (0.42-1.00), respectively.

Utility of p16/Ki67 double immunocytochemistry for detection of cervical adenocarcinoma

BACKGROUND

Although the incidence of cervical adenocarcinoma has consistently increased, especially among young women, there is no established best means for screening. This study evaluated the screening efficacy of CINtec PLUS (CINtec; p16/Ki67 double immunocytochemistry) expression in cervical glandular cells.

METHODS

Cervical cytology was examined using abnormal glandular cells. The CINtec status of 100 samples with corresponding surgically resected specimens and 11 samples that exhibited negative results for intraepithelial lesion or malignancy at follow-up was analyzed. Additionally, 31 negative samples containing benign glandular cells were included.

RESULTS

Of the 142 samples, CINtec status was diffusely positive in 74, focally positive in 24, and negative in 44. The 74 diffusely positive samples included 70 adenocarcinomas (62 cervical, seven uterine, and one ovarian) and four cases of high-grade cervical intraepithelial neoplasia. The 24 focally positive samples included 15 adenocarcinomas (seven cervical, seven uterine, and one fallopian tube) and nine without malignancy. The 44 negative samples included nine adenocarcinomas (five uterine and four cervical) and 35 without malignancy. The sensitivity, specificity, positive predictive value, and negative predictive value of the CINtec diffusely or focally positive cases for cervical adenocarcinomas were 94.5%, 58.0%, 70.4%, and 90.9%, respectively. In CINtec diffusely positive cases, the respective values were 84.9%, 82.6%, 83.8%, and 83.8%, and in women aged ≤39 years the values were 90.6%, 89.5%, 93.5%, and 85.0%, respectively.

CONCLUSIONS

CINtec may support efficient detection of cervical adenocarcinomas.

Conventional Direct Smear Yields Diagnostic Indicators of Gastric-Type Mucinous Carcinoma Compared with Cytomorphological Features Identified by Liquid-Based Cervical Cytology

INTRODUCTION

Gastric-type mucinous carcinoma (GAS) of the uterine cervix is an adenocarcinoma subtype with a gastric phenotype that poses diagnostic pitfalls in cervical screening cytology because of its blunt morphologic atypia and the limited utility of human papillomavirus testing and ancillary immunochemical staining. Despite the recent widespread uptake of liquid-based cytology (LBC) systems, the cytomorphological features of GAS in LBC samples and the differential features between GAS and usual-type endocervical adenocarcinoma (UEA) remain unclear.

METHODS

Eight GAS cases, all of which were surgically treated following histological confirmation, were examined. Direct Papanicolaou-stained smears and LBC samples were reviewed and compared with 10 UEA cases as controls. Featured cytomorphological findings were as follows: background (mucinous, inflammatory, or necrotic), cell crowding (size of neoplastic cell clusters), cytoplasm (golden mucin and cell border), and nuclei (nuclear chromatin and nucleoli).

RESULTS

Of 18 adenocarcinomas, 16 were detected against a non-mucinous background in LBC samples, most of which were accompanied by mild to moderate inflammation. Clusters comprising >300 neoplastic cells were identified in both GAS and UEA in conventional smears (CSs), while no LBC samples harboured clusters as large as these. Cell borders of GAS were more distinct than those of UEA in CSs (p < 0.001), although fewer populations of neoplastic clusters revealed distinct cell borders in both GAS and UEA in LBC samples. Three of 8 and 2 of 8 GAS cases had golden mucin in CSs and in LBC samples, respectively, which was not detected in UEA at all. Nucleoli against fine nuclear chromatin were more pronounced in GAS than in UEA on CS (p = 0.03), although the difference between GAS and UEA was not apparent in LBC samples.

DISCUSSION/CONCLUSION

This study demonstrated that the diagnostic clues to detect GAS using the conventional approach, namely distinct cell borders and prominent nucleoli, are not useful for excluding UEA in LBC samples. Conventional cervical smears may indicate a diagnosis of GAS; however, specific high-risk HPV detection approaches, such as HPV test or immunocytochemical p16/Ki-67 dual staining, are desirable to differentiate GAS from UEA in the setting of LBC with ambiguous cytomorphological features.

Detection of pagetoid urothelial intraepithelial neoplasia extending to the vagina by cervical screening cytology: a case report with renewed immunochemical summary

Background

Pagetoid spread of urothelial carcinoma (UC) to the lower genital tract is quite a rare and diagnostically challenging condition. Pagetoid urothelial intraepithelial neoplasia extending to the vagina is difficult to diagnose, especially in remote recurrences without symptomatic or macroscopic lesions typical to Paget disease. However, its identification by cervical screening cytology is important because UC is often characterized by a long history of relapse.

Case presentation

A 68-year-old Japanese postmenopausal woman developed brown vaginal discharge after radical cystectomy for bladder cancer (high-grade UC, pT2a pN0 cM0 [Union for International Cancer Control, 8th edition]) concomitant with focal in-situ UC in the urethra. She had a history of left renal pelvis UC, which was surgically removed 9 months before the radical cystectomy. Gynecologic examination of the lower genital tract was unremarkable although cervical screening cytology demonstrated severely atypical cells with pleomorphism repeatedly. Cervical colposcopy and diagnostic conization revealed no cervical neoplasm. In retrospect, immunocytochemical p16/Ki-67 dual staining for the previous cervical screening was negative for p16 labeling, and the neoplastic cells were positive for cytokeratins 7 and 20, p63, and GATA binding protein 3. No high-risk human papillomavirus genotype was identified by an automated DNA chip system using liquid-based cytology samples. Eleven months post-cystectomy, punch biopsy of the vulva and vagina confirmed intraepithelial UC in the juxtaposed squamous epithelium with pagetoid spread demonstrating positivity for specific urothelial markers: uroplakins II and III and thrombomodulin. Concurrent invasive malignancy was ruled out, and CO₂ laser vaporization of the vulvar and vaginal lesion was performed. The patient remained alive without evidence of invasive malignancy for 14 months after the radical cystectomy for bladder cancer.

Conclusions

To detect recurrent pagetoid urothelial intraepithelial neoplasia with pagetoid spread in the lower genital tract, pathologists should recognize the history of prior UC with special attention to absence of p16 labeling in cervical cytology as a pointer to the diagnosis of urothelial cancer. Using further biopsy and immunohistochemical confirmation of UC relapse, investigation to rule out invasive malignancies and careful follow-up throughout the patient’s lifetime is recommended.

Evaluation of preoperative positron emission tomography with computed tomography (PET-CT) for detecting lymph node metastasis in gynecologic carcinoma

5593

Background: To evaluate the sensitivety, specificity, and accuracy of PET-CT for detecting lymph node metastasis in gynecologic carcinoma. Methods: Between May 2007 to August 2008, 36 consecutive patients (pts) with cervical carcinoma, endometrial carcinoma and epithelial ovarian carcinoma were enrolled. All pts underwent PET-CT prior to the surgery of systematic pelvic and paraaortic lymphadenectomy. For pathological metastatic lymph nodes, the size of intranodal tumor deposits (maximum diameter of metastatic foci in each lymph node) were recorded. Results: The total number of pelvic lymph nodes (PLNs) plus paraaortic lymph nodes (PANs) removed was 2426. The median number of removed lymph nodes (LNs) was 67 each pts (range: 25 to 102). The number of involvement LNs was 79 (3.5%). The sensitivity, specificity and accuracy of preoperative PET-CT to detect LN metastasis were 24%, 99.9%, and 97.5%, respectively. The sensitivity of PLNs and PANs were 39.5% and 7.3%, respectively. The sensitivity of squamous cell carcinoma (SCC) were 35.7%, that of adenocarcinoma were 8.1%. FDG-PET detected 100% of intranodal tumor deposits > or =10 mm, whereas tumor deposits smaller than 5 mm were not detected. Conclusions: The results of our study revealed 76% underdiagnosis (overlooking) in evaluation of preoperative PET-CT in LN metastasis. Particularly, tumor deposits smaller than 5 mm were not detected at all. Using PET-CT for detecting small LN metastasis in gynecologic carcinoma may be unreliable so far. However we found that PLNs are comparatively easy to be detected than PANs, and SCC are comparatively easy to be detected than adenocarcinoma. The improved usability and application of PET-CT for detecting LN metastasis in gynecologic carcinoma have to keep researching constructively.

No significant financial relationships to disclose.

Pulmonary clearance of aerosolized 99mTc-DTPA in sarcoidosis I patients

AIM

Sarcoidosis frequently affects the lungs of patients. Pulmonary clearance scintigraphy with Technetium-99m-diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) aerosol may assess pulmonary involvement of sarcoidosis patients. The study investigated early pulmonary involvement of sarcoidosis I patients by assessing the pulmonary clearance of inhaled (99m)Tc-DTPA aerosol and the character of pulmonary clearance though systemic steroid therapy.

METHODS

The pulmonary clearance of (99m)Tc-DTPA aerosol was investigated in 24 patients with suspected stage I sarcoidosis and 20 non-smoking healthy controls over 18 months. The radiological finding was evaluated by chest computed radiography (CR) and high resolution computed tomography (HRCT) and the histological diagnosis was performed by transbronchial lung biopsy and/or Scalen node biopsy. The sarcoidosis I patients with ocular involvement underwent 1 year-systemic steroid therapy and were followed up over totally 18 months.

RESULTS

The histological diagnosis was proved in 13 out of the 24 patients that had no lung filed involvement on CR and HRCT. Accelerated pulmonary clearance of (99m)Tc-DTPA was observed in 10 out of the 13 sarcoidosis I patients. Nine out of 13 sarcoidosis I patients underwent systemic steroid therapy due to ocular involvement and the accelerated pulmonary clearance responded to therapy and improved in all of the 9 over 18 months.

CONCLUSIONS

Acceleration of (99m)Tc-DTPA pulmonary clearance may be observed in sarcoidosis I patients and the acceleration will respond to systemic steroid therapy. Pulmonary clearance scintigraphy with (99m)Tc-DTPA aerosol may be useful for assessing pulmonary involvement before radiological changes emerge and sarcoidosis I patients with accelerated pulmonary clearance may undergo systemic steroid treatment.

Comparison of patient doses in 256-slice CT and 16-slice CT scanners

The 256-slice CT-scanner has been developed at the National Institute of Radiological Sciences. Nominal beam width was 128 mm in the longitudinal direction. When scanning continuously at the same position to obtain four-dimensional (4D) images, the effective dose is increased in proportion to the scan time. Our purpose in this work was to measure the dose for the 256-slice CT, to compare it with that of the 16-slice CT-scanner, and to make a preliminary assessment of dose for dynamic 3D imaging (volumetric cine imaging). Our group reported previously that the phantom length and integration range for dosimetry needed to be at least 300 mm to represent more than 90% of the line integral dose with the beam width between 20 mm and 138 mm. In order to obtain good estimates of the dose, we measured the line-integral dose over a 300 mm range in PMMA (polymethylmethacrylate) phantoms of 160 mm or 320 mm diameter and 300 mm length. Doses for both CT systems were compared for a clinical protocol. The results showed that the 256-slice CT generates a smaller dose than the 16-slice CT in all examinations. For volumetric cine imaging, we found an acceptable scan time would be 6 s to 11 s, depending on examinations, if dose must be limited to the same values as routine examinations with a conventional multidetector CT. Finally, we discussed the studies necessary to make full use of volumetric cine imaging.

Effect of calcium trisodium DTPA in rats with puncture wound contaminated by 90Y-chloride

The efficacy of diethylenetriaminepentaacetate calcium trisodium (CaNa(3)DTPA) in a dose of 34.7 micromol kg(-1) as a function of its route of administration was investigated in rats with a puncture wound contaminated by (90)Y-chloride at a concentration of 2.55 MBq kg(-1). Approximately 60% of (90)Y-chloride at a puncture wound was absorbed into the body of rats over 72 h post-puncture and radioactivity in femoral bone increased during the timed-release of (90)Y. Intravenous administration of CaNa(3)DTPA (systemic treatment) at 15 min post-puncture reduced (90)Y at a puncture wound and in bone up to 75.6 and 84.3% of controls, respectively. Direct infiltration of CaNa(3)DTPA into a puncture wound site (local treatment) at 15 min post-puncture diminished radioactivity at the puncture wound and in bone up to 34.9 and 52.5% of controls, respectively. Thus, prompt local treatment may be effective for removing (90)Y from a puncture wound and minimising (90)Y-distribution to bone compared with systemic treatment.

The amygdala and Alzheimer's disease: positron emission tomographic study of the cholinergic system

The primary transmitter deficit is cholinergic in Alzheimer's disease (AD), and the amygdala receives a major cholinergic projection from the nucleus basalis of Meynert (Ch4), which may play an important role in the retention of affective conditioning and/or memory consolidation. We measured brain acetylcholinesterase (AChE) activity in 54 patients with AD and in 22 normal controls by positron emission tomography and N-[(11)C]methylpiperidin-4-yl acetate to characterize the cholinergic pathology in AD. The k(3) values were calculated as an index of AChE activity in a three-compartment model analysis using the metabolite-corrected arterial input function. The k(3) values were highly significantly reduced by 20% in the cerebral neocortex (P <0.0001 in the two-tailed t test), 14% in the hippocampus (P <0.001), and 33% in the amygdala (P <0.0001) in AD patients compared with normal controls. The k(3) values were significantly correlated with the Mini-Mental State Examination scores in both the cerebral cortex (P <0.001) and the amygdala (P <0.05) in AD patients, supporting the cholinergic hypothesis of cognitive dysfuncion in AD. Further studies are required, however, to elucidate the specific role of the cholinergic deficit in the amygdala in the emotional and behavioral symptoms in AD.

11C-choline PET for the detection of bone and soft tissue tumours in comparison with FDG PET

We assessed and compared the usefulness of C-choline positron emission tomography (PET) with that of 2-[ F]fluoro-2-deoxy-D-glucose (FDG) PET for the differentiation between benign and malignant bone and soft tissue tumours. A total of 43 patients with 45 lesions were included. C-choline PET and FDG PET were performed from 5 and 40 min, respectively, after injection of 275-370 MBq tracer. PET data were evaluated by using the standardized uptake value (SUV) and were analysed according to the pathological data. C-choline uptake in malignancies was 4.9+/-2.1 (n=14), which was significantly higher than that in benign lesions (2.5+/-1.7, n=31) (P <0.0001). The sensitivity, specificity and accuracy of C-choline PET were 100%, 64.5% and 75.6%, respectively, when 2.59 of the SUV was used as the cut-off value. The FDG uptake in malignancies was 5.1+/-4.2 (n=14) and was also significantly larger than that in benign lesions 2.9+/-2.9 (n=31) (P<0.003). The sensitivity, specificity and accuracy of FDG PET were 85.7%, 41.9% and 55.6%, respectively (cut-off=1.83). The C-choline uptake in the lesions correlated with FDG uptake ( r=0.61, P<0.003). In receiver operating characteristic (ROC) analysis, the area under the ROC curve for C-choline PET (area=0.847) was higher than that for FDG PET (area=0.717). This study showed that C-choline PET was superior to FDG PET in differentiation between malignant and benign lesion in bone and soft tissue tumours. C-choline PET might be useful as a screening method for malignant bone and soft tissue tumours.

Distinctly abnormal brain metabolism in late-onset ornithine transcarbamylase deficiency

OBJECTIVE

To assess alterations in brain metabolites in patients with late-onset ornithine transcarbamylase deficiency (OTCD).

METHODS

Six unrelated, asymptomatic Japanese late-onset OTCD patients were analyzed by proton MRS ((1)HMRS) using a point-resolved spectroscopy technique (repetition and echo times, 5000 and 30 ms). Localized spectra for the centrum semiovale were acquired and absolute metabolite concentrations were calculated using an LCModel.

RESULTS

Compared with age-matched controls, N-acetylaspartate and creatine concentrations were normal in all patients. The glutamine (Gln) plus glutamate concentration was increased in four patients, which progressed in proportion to the clinical stage. myo-inositol (mI) could not be detected in five symptomatic patients. A decreased choline (Cho) concentration was detected in two clinically severe patients. (1)HMRS after liver transplantation in one patient revealed the normalization of all metabolites.

CONCLUSION

These findings suggest progression of neurochemical events in OTCD, i.e., mI depletion and Gln accumulation followed by Cho depletion, which is reverse of that in hepatic encephalopathy, i.e., Cho depletion followed by mI depletion and Gln accumulation.

Oncological diagnosis using positron coincidence gamma camera with fluorodeoxyglucose in comparison with dedicated PET

The purpose of this study was to compare the utility of a dual-head positron coincidence detection gamma camera (PCD) with that of dedicated positron emission tomography (PET) in the imaging of various malignancies using (18)F-fluorodeoxyglucose (FDG). 25 patients with known or suspected malignancies at various sites underwent imaging with both methods, and diagnostic performance on a lesion basis was compared. Tumour lesions were analyzed visually and semi-quantitatively using the ratio of tumour-to-background counts (T/B ratio). FDG PCD and FDG PET visually detected 34 (72.3%) lesions and 37 (78.7%) lesions, respectively. The mean T/B ratio and standard deviation (SD) of FDG PCD was 3.5+/-3.3, significantly lower than that of FDG PET (8.4+/-7.1, p<0.001). When tumour lesions were less than 2.0 cm in diameter, the sensitivity of FDG PCD was 37.5%, significantly inferior to that of FDG PET (50.0%, p<0.01). Sensitivity between FDG PCD and FDG PET in lesions of more than 2.0 cm diameter showed no statistically significant difference. This study indicates that FDG imaging with a dual-head coincidence detection gamma camera can provide suitable diagnostic performance for lesions greater than 2.0 cm diameter, but performed significantly worse than dedicated PET for lesions smaller than this.