Impact of Single-Time-Point Estimates of 177Lu-PRRT Absorbed Doses on Patient Management: Validation of a Trained Multiple-Linear-Regression Model in 159 Patients and 477 Therapy Cycles

Article Figures & Data

Download figure
Open in new tab
Download powerpoint
Download figure
Open in new tab
Download powerpoint
FIGURE 1.
Bland–Altman (A) and correlation (B) plots between cumulative kidney ADs after 4 PRRT cycles calculated with STP and MTP protocols.
Download figure
Open in new tab
Download powerpoint
FIGURE 2.
Bland–Altman (A) and correlation (B) plots between cumulative liver ADs after 4 PRRT cycles calculated with STP and MTP protocols.
Download figure
Open in new tab
Download powerpoint
FIGURE 3.
Bland–Altman (A) and correlation (B) plots between cumulative spleen ADs after 4 PRRT cycles calculated with STP and MTP protocols.
Download figure
Open in new tab
Download powerpoint
FIGURE 4.
Bland–Altman (A) and correlation (B) plots between cumulative tumor ADs after 4 PRRT cycles calculated with STP and MTP protocols.

TABLE 1.

Patients’ Demographic and Clinical Data

TABLE 2.

Regression Coefficients of STP MLR Model in Solid Organs and Tumors

	First therapy cycle (t_s = 168 h)			Subsequent therapy cycles (t_s = 24 h)
Site	(ln[cm³·mGy/37·MBq])	(no units)	(h⁻¹)	(ln[cm³·mGy/37·MBq])	(no units)	(h⁻¹)
Kidneys	11.86	0.85	0.0111	12.01	0.91	0.0153
Liver	12.26	0.90	0.0090	12.37	0.96	0.0205
Spleen	12.51	0.95	0.0094	12.21	1.00	0.0336
Tumors	12.80	0.99	0.0086	12.80	0.99	0.0086

TABLE 3.

Regression Coefficients of STP MLR Model in Bone Marrow

Therapy cycle	(cm³·mGy/37·MBq·h)	(cm³·mGy/37·MBq·h)	(ln[h])	(no units)	(h⁻¹)
First (t_s = 168 h)	1,879	316	4.59	0.90	0.0101
Subsequent (t_s = 24 h)	1,868	319	4.26	1.07	0.0241

TABLE 4.

Differences Between STP and Our MTP Calculations

STP MLR vs. MTP	Kidneys (n = 167)	Bone marrow (n = 27)	Liver (n = 170)	Spleen (n = 150)	Tumors (n = 311)
Group 1, one cycle (n = 32)
Relative difference	−1.6% ± 13.1% (n = 32)	−0.8% ± 11.0% (n = 12)	0.4% ± 8.3% (n = 32)	1.6% ± 2.4% (n = 28)	−9.0% ± 17.9% (n = 56)
Median	−3.6%	−2.0%	1.2%	2.4%	−3.1%
Range	−31%–33%	−17%–31%	−21%–17%	−15%–22%	−69%–11%
Angular coefficient	1.03	0.99	0.98	0.97	0.98
Group 2, two cycles (n = 36)
Relative difference	−0.3% ± 2.5% (n = 33)	2.9% (n = 1)	2.5% ± 4.7% (n = 36)	−3.2% ± 4.9% (n = 34)	−1.3% ± 9.3% (n = 63)
Median	−0.9%	—	2.5%	−2.4%	0.1%
Range	−12%–12%	—	−8%–15%	−15%–4%	−33%–21%
Angular coefficient	1.03	—	1.00	1.05	1.00
Group 3, three cycles (n = 45)
Relative difference	−0.8% ± 5.5% (n = 45)	−1.3% ± 2.8% (n = 8)	2.5% ± 8.7% (n = 43)	−2.5% ± 6.2% (n = 38)	−2.0% ± 13.5% (n = 87)
Median	−0.2%	−1.1%	3.9%	−3.7%	−1.3%
Range	−13%–17%	−6%–2%	−21%–23%	−19%–13%	−41%–32%
Angular coefficient	1.03	1.01	1.07	1.02	1.07
Group 4, four cycles (n = 57)
Relative difference	0.8% ± 8.0% (n = 56)	−7.7% ± 4.8% (n = 5)	−0.0% ± 11.4% (n = 57)	−2.8% ± 6.3% (n = 48)	−2.1% ± 18.4% (n = 101)
Median	1.5%	−6.7%	0.9%	−2.9%	−1.9%
Range	−30%–19%	−15%–3%	−21%–18.3%	−23%–11%	−62%–89%
Angular coefficient	1.00	1.10	1.09	1.02	1.04
Five cycles (n = 2), relative difference	−4.6% (n = 1)	−3.0% (n = 1)	2.4% ± 4.8% (n = 2)	−2.6% ± 1.4% (n = 2)	−9.2% ± 11.2% (n = 4)