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Efficacy of 18F-FDG PET/CT in investigation of elevated CEA without known primary malignancy

View Article: PubMed Central - PubMed

ABSTRACT

Aim:: To evaluate the efficacy of 18flurodeoxyglucose positron emission tomography/computer tomography (18F-FDG PET/CT) in investigating patients with elevated carcinoembryonic antigen (CEA) and without known primary malignancy, and the impact of PET/CT findings on patient management.

Setting and design:: PET/CT scans done in a tertiary hospital between December 2007 and February 2012 for elevated CEA in patients without known primary malignancy were retrospectively reviewed.

Materials and methods:: The PET/CT findings, patients' clinical information, level of CEA, histological diagnosis, and subsequent management were retrieved by the electronic patient record for analysis.

Statistical analysis:: Data were analyzed using SPSS version 19.

Results:: One hundred and one PET/CT scans were performed for patients with elevated CEA. Fifty-eight of these were performed for patients with known primary malignancy and were excluded; 43 PET/CT scans were performed for patients without known primary malignancy and were included. Thirty-three (77%) had a positive PET/CT. Among the 32 patients with malignancy, 15 (47%) suffered from lung cancer and 8 (25%) suffered from colorectal cancer. The sensitivity (97%), specificity (82%), positive predictive value (94%), negative predictive value (90%), and accuracy (93%) were calculated. Thirty (91%) patients had resultant change in management. The mean CEA level for patients with malignancy (46.1 ng/ml) was significantly higher than those without malignancy (3.82 ng/ml) (P < 0.05). In predicting the presence of malignancy, a CEA cutoff at 7.55 ng/ml will achieve a sensitivity of 91% and a specificity of 73%.

Conclusion:: PET/CT, in our study population, appears to be sensitive, specific, and accurate in investigating patients with elevated CEA and without known primary malignancy. In addition to diagnosis of underlying primary malignancy, PET/CT also reveals occult metastases which would affect patient treatment options. Its role in investigating patients with elevated CEA and without known primary, compared with other investigation modalities, remains to be studied.

No MeSH data available.


Related in: MedlinePlus

(A) Axial and coronal images of fusion PET/CT showing a hypermetabolic (SUVmax: 10.0) left lower lobe mass suspicious of lung cancer with mediastinal nodal metastases. (B) Frontal chest radiograph of the same patient, showing a retrocardiac mass (arrows). (C) Axial, coronal, and sagittal CT images of the same patient confirming an irregular soft tissue lung mass at the retrocardiac region
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Figure 1: (A) Axial and coronal images of fusion PET/CT showing a hypermetabolic (SUVmax: 10.0) left lower lobe mass suspicious of lung cancer with mediastinal nodal metastases. (B) Frontal chest radiograph of the same patient, showing a retrocardiac mass (arrows). (C) Axial, coronal, and sagittal CT images of the same patient confirming an irregular soft tissue lung mass at the retrocardiac region

Mentions: In the authors' institution, informed consent and institutional ethics review were waived for retrospective study. PET/CT scans done in a tertiary hospital between December 2007 and February 2012 for elevated CEA (>2.5 ng/ml) were reviewed. Patients without known primary malignancy were included, whereas those with known primary malignancy were excluded. In the authors' institution, patients presenting with elevated CEA are first assessed by the clinician, who obtains a detailed medical history and performs a comprehensive physical examination to identify the most likely source of elevated CEA. Depending on the organ system concerned, this is followed by specific investigations, such as chest radiograph, computed tomography, bronchoscopy, colonoscopy, etc., PET/CT is also an option, but it is not a publically funded investigation and can only be performed in patients who can afford the cost. The choice of investigation relies on the clinical judgment of the referring clinicians. Therefore, at the time of PET/CT, the investigations received by the patients were variable. Patients were regarded to have no known primary malignancy if there was no clinical history, physical examination findings, and available imaging and pathological findings to suggest a likely primary malignancy. On the contrary, patients were regarded to have known malignancy if there was such evidence on clinical history (e.g., known lung cancer), physical examination findings (e.g., a rectal mass), and available imaging/endoscopic (e.g., lung mass on chest radiograph, colonic mass on colonoscopy) or pathological (e.g. biopsy-proven malignancy) examinations. PET/CT was performed using Philips Gemini GXL scanner (Philips Medical Systems International BV, Best, The Netherlands). Patients were fasted for 6 hours before scanning. Blood glucose level was monitored and insulin was given if the blood glucose level exceeded 11 mmol/l. Then 10 mCi 18-FDG was injected intravenously and the patients were asked to rest for 1 hour before scanning. PET images (4 mm slice thickness) were first acquired from vertex to below the knee, followed by low-dose plain CT (5 mm slice thickness; Philips 16-slice MDCT; 30 mA, 140 kV) for attenuation correction and anatomical correlation (to register the anatomical location of tracer activity). PET acquisition was usually covered by 12–15 beds of scanning. Each bed covered a length of 180 mm and was counted in 90-s segments. The total length of coverage was 1104–1356 mm. Depending on the referral request, supplementary diagnostic CT with or without intravenous contrast would be performed. The images were processed and viewed using Philips Extended Brilliance (TM) Workspace, as exemplified in Figure 1A. The PET/CT findings, including the size, site, number, and maximal standardized uptake value (SUVmax) of the lesions, were retrieved. Patients' clinical information, including age, sex, diabetic status, smoking status, level of CEA before PET/CT, other investigations performed (such as chest radiograph, bronchoscopy, colonoscopy, etc.), and the results, histological diagnosis, and subsequent management were retrieved by the electronic patient record for analysis. A positive PET/CT is defined as a PET/CT which detects the presence of primary malignancy based on morphological lesions or abnormal hypermetabolic (e.g., SUVmax > 2.5) focus. A negative PET/CT is defined as a PET/CT which is normal, shows incidental benign lesions, or is inconclusive for the presence of primary malignancy. Change in management is defined as identification of occult distant metastases which would preclude surgical resection. The gold standard to confirm the presence of primary malignancy is histological confirmation. If the suspected lesion was accessible by endoscopy, a negative endoscopy (i.e., no lesion detected) would also be considered as the gold standard to confirm absence of malignancy. If no biopsy or endoscopy is performed, a follow-up for at least 6 months would be used. Patients who remain well without clinical or radiological evidence of primary malignancy are considered negative for primary malignancy and vice versa.


Efficacy of 18F-FDG PET/CT in investigation of elevated CEA without known primary malignancy
(A) Axial and coronal images of fusion PET/CT showing a hypermetabolic (SUVmax: 10.0) left lower lobe mass suspicious of lung cancer with mediastinal nodal metastases. (B) Frontal chest radiograph of the same patient, showing a retrocardiac mass (arrows). (C) Axial, coronal, and sagittal CT images of the same patient confirming an irregular soft tissue lung mass at the retrocardiac region
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036343&req=5

Figure 1: (A) Axial and coronal images of fusion PET/CT showing a hypermetabolic (SUVmax: 10.0) left lower lobe mass suspicious of lung cancer with mediastinal nodal metastases. (B) Frontal chest radiograph of the same patient, showing a retrocardiac mass (arrows). (C) Axial, coronal, and sagittal CT images of the same patient confirming an irregular soft tissue lung mass at the retrocardiac region
Mentions: In the authors' institution, informed consent and institutional ethics review were waived for retrospective study. PET/CT scans done in a tertiary hospital between December 2007 and February 2012 for elevated CEA (>2.5 ng/ml) were reviewed. Patients without known primary malignancy were included, whereas those with known primary malignancy were excluded. In the authors' institution, patients presenting with elevated CEA are first assessed by the clinician, who obtains a detailed medical history and performs a comprehensive physical examination to identify the most likely source of elevated CEA. Depending on the organ system concerned, this is followed by specific investigations, such as chest radiograph, computed tomography, bronchoscopy, colonoscopy, etc., PET/CT is also an option, but it is not a publically funded investigation and can only be performed in patients who can afford the cost. The choice of investigation relies on the clinical judgment of the referring clinicians. Therefore, at the time of PET/CT, the investigations received by the patients were variable. Patients were regarded to have no known primary malignancy if there was no clinical history, physical examination findings, and available imaging and pathological findings to suggest a likely primary malignancy. On the contrary, patients were regarded to have known malignancy if there was such evidence on clinical history (e.g., known lung cancer), physical examination findings (e.g., a rectal mass), and available imaging/endoscopic (e.g., lung mass on chest radiograph, colonic mass on colonoscopy) or pathological (e.g. biopsy-proven malignancy) examinations. PET/CT was performed using Philips Gemini GXL scanner (Philips Medical Systems International BV, Best, The Netherlands). Patients were fasted for 6 hours before scanning. Blood glucose level was monitored and insulin was given if the blood glucose level exceeded 11 mmol/l. Then 10 mCi 18-FDG was injected intravenously and the patients were asked to rest for 1 hour before scanning. PET images (4 mm slice thickness) were first acquired from vertex to below the knee, followed by low-dose plain CT (5 mm slice thickness; Philips 16-slice MDCT; 30 mA, 140 kV) for attenuation correction and anatomical correlation (to register the anatomical location of tracer activity). PET acquisition was usually covered by 12–15 beds of scanning. Each bed covered a length of 180 mm and was counted in 90-s segments. The total length of coverage was 1104–1356 mm. Depending on the referral request, supplementary diagnostic CT with or without intravenous contrast would be performed. The images were processed and viewed using Philips Extended Brilliance (TM) Workspace, as exemplified in Figure 1A. The PET/CT findings, including the size, site, number, and maximal standardized uptake value (SUVmax) of the lesions, were retrieved. Patients' clinical information, including age, sex, diabetic status, smoking status, level of CEA before PET/CT, other investigations performed (such as chest radiograph, bronchoscopy, colonoscopy, etc.), and the results, histological diagnosis, and subsequent management were retrieved by the electronic patient record for analysis. A positive PET/CT is defined as a PET/CT which detects the presence of primary malignancy based on morphological lesions or abnormal hypermetabolic (e.g., SUVmax > 2.5) focus. A negative PET/CT is defined as a PET/CT which is normal, shows incidental benign lesions, or is inconclusive for the presence of primary malignancy. Change in management is defined as identification of occult distant metastases which would preclude surgical resection. The gold standard to confirm the presence of primary malignancy is histological confirmation. If the suspected lesion was accessible by endoscopy, a negative endoscopy (i.e., no lesion detected) would also be considered as the gold standard to confirm absence of malignancy. If no biopsy or endoscopy is performed, a follow-up for at least 6 months would be used. Patients who remain well without clinical or radiological evidence of primary malignancy are considered negative for primary malignancy and vice versa.

View Article: PubMed Central - PubMed

ABSTRACT

Aim:: To evaluate the efficacy of 18flurodeoxyglucose positron emission tomography/computer tomography (18F-FDG PET/CT) in investigating patients with elevated carcinoembryonic antigen (CEA) and without known primary malignancy, and the impact of PET/CT findings on patient management.

Setting and design:: PET/CT scans done in a tertiary hospital between December 2007 and February 2012 for elevated CEA in patients without known primary malignancy were retrospectively reviewed.

Materials and methods:: The PET/CT findings, patients' clinical information, level of CEA, histological diagnosis, and subsequent management were retrieved by the electronic patient record for analysis.

Statistical analysis:: Data were analyzed using SPSS version 19.

Results:: One hundred and one PET/CT scans were performed for patients with elevated CEA. Fifty-eight of these were performed for patients with known primary malignancy and were excluded; 43 PET/CT scans were performed for patients without known primary malignancy and were included. Thirty-three (77%) had a positive PET/CT. Among the 32 patients with malignancy, 15 (47%) suffered from lung cancer and 8 (25%) suffered from colorectal cancer. The sensitivity (97%), specificity (82%), positive predictive value (94%), negative predictive value (90%), and accuracy (93%) were calculated. Thirty (91%) patients had resultant change in management. The mean CEA level for patients with malignancy (46.1 ng/ml) was significantly higher than those without malignancy (3.82 ng/ml) (P < 0.05). In predicting the presence of malignancy, a CEA cutoff at 7.55 ng/ml will achieve a sensitivity of 91% and a specificity of 73%.

Conclusion:: PET/CT, in our study population, appears to be sensitive, specific, and accurate in investigating patients with elevated CEA and without known primary malignancy. In addition to diagnosis of underlying primary malignancy, PET/CT also reveals occult metastases which would affect patient treatment options. Its role in investigating patients with elevated CEA and without known primary, compared with other investigation modalities, remains to be studied.

No MeSH data available.


Related in: MedlinePlus