Identifying hypoxia in human tumors: A correlation study between ¹⁸F-FMISO PET and the Eppendorf oxygen-sensitive electrode

Figures & data

Figure 1. The virtual voxel histogram. For each tumor the Eppendorf pO₂ measurements of seven successive pO₂ values were aligned to resemble signal obtained from an ¹⁸F-FMISO PET voxel in one dimension (A). Eppendorf pO₂ measurements from patient number 5 (B) converted to a virtual voxel histogram (C). ¹⁸F-FMISO PET data from patient number 5 (D) converted to a virtual voxel histogram (E). A corresponding virtual voxel histogram from patient number 2 (F). For direct comparison with the Eppendorf virtual voxel histogram the ¹⁸F-FMISO data (percentage of “hypoxia within voxel”) was rounded to nearest seventh part percent (0, 14, 28 … or 100%).

Table I. Patient and tumor characteristics.

Patient number	Histology	Tumor volume (ml)	No. of pO2measurements	No. of Eppendorf tracks	HF5 (%)	^18F-FMISO T/M (median)	Eppendorf virtual voxel median hypoxia (%)	^18F-FMISO virtual voxel medianhypoxia (%)
1	Benign	14^a	56	4	9	1.05	0	0
2	Benign	59^b	230	8	37	0.88	14	0
3	Benign	54^b	93	7	39	0.99	43	0
4	Benign	477^b	123	6	24	0.77	0	0
5	HNSCC	107^c	183	10	74	1.87	100	29
6	HNSCC	80^a	213	6	13	2.38	0	57
7	HNSCC	30^a	56	6	48	1.68	43	29
8	HNSCC	6^b	86	5	47	1.19	64	0
9	HNSCC	7^a	67	5	31	1.30	14	14
10	HNSCC	25^a	105	6	55	1.94	57	29
11	HNSCC	7^a	81	6	94	1.14	100	0
12	HNSCC	56^a	112	4	69	2.21	71	43
13	HNSCC	15^b	70	5	43	1.12	43	0
14	Sarcoma	303^a	192	6	42	0.79	29	0
15	Sarcoma	2593^a	179	9	68	0.70	86	0
16	Sarcoma	20^b	131	7	19	0.97	0	0
17	Sarcoma	727^b	192	7	68	0.71	79	0
28	Sarcoma	105^b	83	7	20	1.40	0	14

^aVolume defined by MR/¹⁸F-FMISO PET.

^bVolume defined by clinical examination/¹⁸F-FMISO PET.

^cVolume defined by ¹⁸FDG PET/¹⁸F-FMISO PET.

Figure 2. Three examples of ¹⁸F-FMISO tumor imaging and the corresponding virtual voxel histograms. A: Patient number 1 with concordance between Eppendorf pO₂ measurements and ¹⁸F-FMISO PET (both showing little/no hypoxia). B: Patient number 12 likewise with concordance between Eppendorf pO₂ measurements and ¹⁸F-FMISO PET (both showing hypoxia). C: Patient number 15 with lack of con cordance between Eppendorf pO₂ measurements (showing high degree of hypoxia) and ¹⁸F-FMISO PET (showing very little hypoxia).

Figure 3. Comparison between the virtual voxel median hypoxia measured by Eppendorf pO₂ electrodes and ¹⁸F-FMISO PET, respectively. The dotted line indicates an ideal situation with total concordance between the two different assays. Red symbol: HNSCC. Blue symbol: Benign tumors. Green symbol: Soft tissue tumors. A, B, C refers to tumor categories as exemplified in figure 2.