Predicting spatial gene expression from histology images could scale spatial transcriptomics (ST) to image-only cohorts, but conventional histology-based ST prediction is trained and evaluated mainly by per-gene spatial-profile reconstruction. This objective is misaligned with a key downstream use of ST: differentially expressed gene (DEG) discovery, where genes are ranked for a biological or morphology-defined contrast by evidence of between-group expression differences. We formulate image-based differential expression ranking (IDER), which asks whether predicted expression profiles preserve the contrast-specific ranked gene list obtained from measured profiles. IDER compares gene rankings induced by differential-expression statistics, rather than raw expression magnitudes or per-gene spatial correlations. We further introduce a differentiable IDER objective that aligns these statistics across genes and can be trained with morphology-derived proxy contrasts without predefined biological group labels. Experiments on public ST datasets show improved DEG-ranking agreement and pathway-enrichment overlap over conventional reconstruction objectives, including morphology-derived and pathologist-annotated tissue-region evaluations.
Figures & tables
Figure 1 : (a) Conventional evaluation measures spatial-profile agreement within each gene across spots. (b) Image-based Differential Expression Ranking (IDER) ranks genes by contrast statistics for a biological or morphology-defined comparison and evaluates whether predicted profiles preserve this ranked list of DEG candidates.
Objective
Ovary
Lymph Node
Bowel
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
@50
@100
@200
@50
@100
@200
@50
@100
@200
MSE [ 4 ]
0.587
0.415
0.446
0.434
0.624
0.407
0.434
0.477
0.709
0.364
0.432
0.468
PCC [ 30 ]
0.584
0.425
0.451
0.451
0.629
0.439
0.478
0.521
0.710
0.384
0.461
0.494
MSE & PCC [ 37 ]
0.609
0.437
0.465
0.453
0.650
0.477
0.511
0.548
0.714
0.383
0.459
0.496
Poisson
0.460
0.363
0.401
0.422
0.234
0.448
0.493
0.501
0.694
0.440
0.476
0.492
Table 1 : Comparison of DEG ranking performance in the cluster-based DEG setting against methods optimized with conventional objective functions.
Objective
Ovary
Lymph Node
Bowel
Breast
MSE [ 4 ]
0.326
0.382
0.336
0.144
PCC [ 30 ]
0.341
0.414
0.345
0.127
MSE & PCC [ 37 ]
0.332
0.433
0.314
0.125
Poisson
0.307
0.413
0.362
0.136
NB [ 24 ]
0.289
0.443
0.385
0.143
STRank [ 25 ]
0.302
0.383
0.360
0.147
Table 2 : Analysis of pathway enrichment overlap.
Objective
Average
adipose tissue
connective tissue
immune infiltrate
invasive cancer
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
MSE [ 4 ]
0.239
0.084
0.393
0.069
0.206
0.080
0.197
0.176
0.272
0.082
PCC [ 30 ]
0.181
0.073
0.297
0.060
0.143
0.066
0.132
0.199
0.182
0.035
MSE & PCC [ 37 ]
0.195
0.073
0.317
0.076
0.208
0.048
0.134
0.239
0.216
0.043
Poisson
0.116
0.101
0.123
0.057
0.105
0.109
0.191
0.228
0.114
0.081
NB [ 24 ]
0.137
0.098
0.145
0.038
0.127
0.097
0.190
0.269
0.120
0.073
Table 3 : Comparison of DEG ranking performance in the real annotation-based DEG setting against methods optimized with conventional objective functions, in terms of SCC DEG and nDCGDEG @200. Due to space limitations, nDCGDEG @200 is abbreviated as nDCGDEG .
Objective
Ovary
Lymph Node
Bowel
Her2st
U stat.
DEG rank.
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
SCC DEG
nDCGDEG
Baseline
✗
✗
0.584
0.451
0.629
0.521
0.710
0.494
0.181
0.073
Ours w/o DEG rank.
✓
✗
0.587
0.454
0.617
0.521
0.710
0.491
0.178
0.077
Ours
✓
✓
0.686
0.531
0.676
0.643
0.731
0.595
0.353
0.247
Table 4 : Ablation experiments of the proposed method .
Objective
Ovary
L. N.
Bowel
Breast
MSE [ 4 ]
0.235
0.171
0.345
0.113
PCC [ 30 ]
0.233
0.172
0.345
0.145
MSE & PCC [ 37 ]
0.235
0.172
0.341
0.141
Poisson
0.192
0.126
0.300
0.052
NB [ 24 ]
0.195
0.130
0.303
0.056
STRank [ 25 ]
0.190
0.130
0.300
0.065
Table 5 : Evaluation on per-gene spatial-profile PCC. L. N. indicates Lymph Node.
Objective
Ovary
L. N.
Bowel
Breast
MSE [ 4 ]
0.235
0.171
0.345
0.113
PCC [ 30 ]
0.233
0.172
0.345
0.145
MSE & PCC [ 37 ]
0.235
0.172
0.341
0.141
Poisson
0.192
0.126
0.300
0.052
NB [ 24 ]
0.195
0.130
0.303
0.056
STRank [ 25 ]
0.190
0.130
0.300
0.065
Table 5 : Evaluation on per-gene spatial-profile PCC. L. N. indicates Lymph Node.
Objective
nDCGDEG
SCC DEG
@50
@100
@200
ST-Net [ 8 ]
0.181
0.060
0.062
0.073
ST-Net + Ours
0.353
0.212
0.230
0.247
TRIPLEX [ 4 ]
0.299
0.079
0.097
0.115
TRIPLEX+ Ours
0.457
0.190
0.212
0.242
Table 6 : Plug-in experiments for existing methods on the Her2st dataset.