Feasibility of Acquisitions Using Total-Body PET/CT with an Ultra-Low 18F-FDG Activity

Yan Hu; Guobing Liu; Haojun Yu; Ying Wang; Chenwei Li; Hui Tan; Shuguang Chen; Jianying Gu; Hongcheng Shi

doi:10.2967/jnumed.121.262038

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FIGURE 1.
PET images of 63-y-old man with esophagus cancer. Coronal slice of whole body (A), transverse view of intense uptake of lesions in esophagus (B), and transverse view of liver (C) are shown in G1, G2, G4, G8, G10, and G15 reconstructions. More superior image quality of liver was observed in G8 than in G1 and G2 on visual assessment.
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FIGURE 2.
Box plot of lesion SUV_max (A), liver SUV_max (B), TBR (C), liver SUV_mean (D), liver SD (E), and SNR (F). Lesion SUV_max, TBR, and SNR increased with extension of acquisition time, whereas liver SUV_max, liver SUV_mean, and SD decreased. Compared with G15, no significant differences for these parameters were found in G8 and G10. *P < 0.05. ns = not significant.
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FIGURE 3.
PET images of 63-y-old man with CRC reconstructed in G8 and another 63-y-old man with CRC reconstructed in g2 (A, coronal slice of the whole body; B, transverse view of CRC lesion [arrow]; C, transverse image of liver). Image quality in G8 was comparable to that in g2, which meets standard for clinical diagnosis.
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FIGURE 4.
Bar graph of values of subjective image quality score (A) and objective parameters (B) between G8 and g2. Comparable result of qualitative and quantitative analysis was shown between the 2 groups. ns = not significant.

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TABLE 1.

Demographics of Patients in Ultra-Low-Activity Group

Variable	Dataset
Sex*
Men	20
Women	10
Age (y)^†	66.1 ± 8.44 (48.00–77.00)
Height (cm)^†	165.5 ± 7.25 (157.00–186.20)
Weight (kg)^†	62.28 ± 10.2 (44.80–88.00)
BMI (kg/m²)^†	22.73 ± 3.28 (15.76–29.75)
Blood glucose (mmol/L)^†	5.75 ± 0.66 (4.80–7.00)
Uptake time (min)^†	60.97 ± 5.96 (51.00–70.00)
Injected dose (MBq)^†	25.53 ± 4.07 (17.76–33.67)
Primary tumor type*
HCC and ICC	4
CRC	11
Lung cancer	1
Pancreatic cancer	3
Esophageal cancer	2
Mediastinal sarcoma	1
Bladder cancer	4
Ovarian cancer	2
Lymphoma	1
Laryngeal cancer	1

* Number of patients.
↵^†Data are presented as mean ± SD followed by range in parentheses.
BMI = body mass index; HCC = hepatocellular carcinoma; ICC = intrahepatic cholangiocarcinoma.

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TABLE 2.

Subjective Image Quality Score in Ultra-Low-Activity Group

Acquisition duration (min)	Image quality score
	Likert scale score		Cohen κ-test result
	Reader 1*	Reader 2*	Intrareader agreement	Interreader agreement
1	1.10 ± 0.31	1.14 ± 0.35	0.898 (0.694–1.000)	0.849 (0.530–1.000)
2	2.07 ± 0.37	2.10 ± 0.41	0.902 (0.711–1.000)	0.885 (0.674–1.000)
4	3.00 ± 0.38	2.90 ± 0.49	0.895 (0.688–1.000)	0.750 (0.492–1.000)
8	4.07 ± 0.53	3.97 ± 0.63	0.900 (0.701–1.000)	0.852 (0.638–1.000)
10	4.38 ± 0.49	4.38 ± 0.49	0.921 (0.738–1.000)	0.854 (0.648–1.000)
15	4.62 ± 0.49	4.59 ± 0.50	0.945 (0.812–1.000)	0.930 (0.790–1.000)

* Mean value and SD were calculated on basis of subjective scores for each patient.
Data in parentheses are 95% CIs.

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TABLE 3.

Quantitative Image Quality in Ultra-Low-Activity Group

Acquisition duration (min)	Lesion SUV_max	Liver SUV_max	TBR
1	12.44 ± 5.00*	4.56 ± 0.86*	2.84 ± 1.36*
2	14.58 ± 6.86	3.80 ± 0.60*	3.89 ± 1.80*
4	16.95 ± 7.78	3.53 ± 0.52	4.83 ± 2.18
8	18.09 ± 8.26	3.31 ± 0.50	5.53 ± 2.50
10	18.37 ± 8.06	3.21 ± 0.46	5.78 ± 2.50
15	18.96 ± 7.93	3.08 ± 0.42	6.18 ± 2.52

* Significant difference compared with that in G15 (P < 0.05).
Data are presented as mean ± SD, based on measurement in ROIs.

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TABLE 4.

SUV_mean, SD, and SNR of Liver

Parameter	Acquisition duration (min)
Parameter	1	2	4	8	10	15
Liver SUV_mean*	2.80 ± 0.48	2.78 ± 0.44	2.77 ± 0.43	2.73 ± 0.38	2.72 ± 0.39	2.70 ± 0.38
Liver SD*	0.56 ± 0.19^†	0.38 ± 0.11^†	0.28 ± 0.08^†	0.21 ± 0.06	0.19 ± 0.06	0.18 ± 0.05
SNR*	5.41 ± 1.53^†	7.67 ± 1.88^†	10.41 ± 2.54^†	13.46 ± 3.13	14.72 ± 3.46	15.65 ± 3.64

* Data are presented as mean ± SD, based on measurement in ROIs.
↵^†Significant difference compared with that in G15 (P < 0.05).

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TABLE 5.

Demographics of Patients in G8 and g2

Variable	G8	g2	P
Sex*			0.201
Men	7	7
Women	4	4
Height (cm)^†	166.05 ± 6.48	167.82 ± 10.01	0.627
Weight (kg)^†	62.96 ± 11.87	71.52 ± 18.22	0.208
BMI (kg/m²)^†	22.75 ± 3.46	25.00 ± 3.92	0.168
Blood glucose (mmol/L)^†	5.81 ± 0.61	5.31 ± 0.53	0.054
Uptake time (min)^†	62.91 ± 5.50	58.00 ± 5.57	0.051
Injected dose (MBq)^†	24.79 ± 4.44	271.21 ± 61.42	<0.001^‡
Pathologic*			1.000
WMDA	10	10
HGIN	1	1

* Number of patients.
↵^†Data are presented as mean ± SD, based on data from each subject.
↵^‡Significant difference between G8 and g2 (P < 0.001).
BMI = body mass index; WMDA = well-to-moderately differentiated adenocarcinoma; HGIN = high-grade intraepithelial neoplasia.

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TABLE 6.

Qualitative Image Quality Score and Quantitative Parameters in the Ultra-Low-Activity Group and Full-Activity Group

Parameter	G8	g2	P
Image quality score	3.91 ± 0.30	3.82 ± 0.60	0.311
Lesion SUV_max	23.43 ± 8.64	24.22 ± 12.15	0.863
Liver SUV_max	3.39 ± 0.54	3.17 ± 0.55	0.354
Liver SUV_mean	2.78 ± 0.33	2.84 ± 0.47	0.747
Liver SD	0.21 ± 0.05	0.23 ± 0.08	0.544
TBR	7.07 ± 2.74	7.56 ± 3.51	0.738
SNR	13.77 ± 2.14	13.40 ± 2.90	0.716

Data are presented as mean ± SD. Mean value and SD were calculated on basis of Likert score for each patient. Mean value and SD of other quantitative parameters were calculated on basis of measurement in ROIs.