Results
This page shows the evaluations in the paper, figure by figure. Each chart is drawn from the source data of its panel, and the source data files are listed under the chart for download. The sections and saved results behind Figs. 2–6 open in the data explorers, and Analyze data evaluates your own predictions.
Reproducible-signal correlation (RSC) largely avoids overstating and understating prediction quality
Pearson correlation with measured RNA expression overstates prediction quality across whole sections and understates prediction quality at fine scales. In HER2ST, a class-mean baseline that predicts one value per tissue region reaches a whole-section Pearson r of 0.111, above the median of 11 published methods (0.108; maximum 0.144). In the colorectal cancer data, the split-half reliability of the measured counts implies that the true expression reaches a Pearson r with measured RNA expression of 1.00 at the broadest scale and 0.44 to 0.57 at the finest scale. RSC scores the true expression near 1 across spatial scales.
Fig. 1b Pitfall of whole-section correlation
Fig. 1c Noise correction across scales
How it was computed. Fig. 1b is described in Methods “Whole-section correlation” and “Class-mean baseline”. For Fig. 1c, the measured counts serve as the true expression, Poisson counts are simulated from the true expression, and the true expression is scored as the prediction. Pearson r with measured RNA expression follows from equation (2) with the split-half reliability of the measured counts (Methods “Expected expression and the mean of the halves”). Panels a and d, an overview of RSC and a summary of Figs. 2–5, are in the figure on the home page.
Evaluation within tissue regions reveals whole-section correlation overstates prediction quality
Whole-section correlation overstates prediction quality within tissue regions. Normalized pairwise accuracy measures how often a prediction identifies which of two spots has higher measured expression, scaled from 0% for a majority-order baseline to 100% for the agreement between two RNA halves. Over 785 genes in eight HER2ST patients, the median of 11 published methods falls from 28.5% on unmatched spot pairs to 6.7% on pairs matched for total transcript count and expression profile (Holm-adjusted P = 0.023) and to 6.6% on matched pairs within the same annotated region. Matched spots can still lie in different regions, and the class-mean baseline scores 6.8% on matched pairs. Within regions, the baseline scores 1.5%, lower than each of the 11 published methods.
Method rankings by whole-section correlation agree closely with rankings on unmatched pairs (Kendall's τb = 0.818) but are nearly unrelated to rankings within regions (τb = 0.091), and the top-ranked method changes from EGNv2 to DeepSpaCE. The same overstatement appears for single genes. Hist2ST predictions of FASN correlate with measured RNA at Spearman ρ = 0.534 across all spots of a section and at ρ = 0.068 among spots within regions.
How it was computed. strsc her2 computes normalized pairwise accuracy on unmatched, matched and within-region spot pairs (Methods “Evaluation between and within tissue regions”). The browser tool Pairwise accuracy runs the same calculation on your data.
Explore: HER2ST cohort (Fig. 2a–c, g–i) · HER2ST section B1 (Fig. 2f)
Reproducible-signal correlation (RSC) reveals spot-level methods mainly capture coarse tissue structure
Spot-level predictions generally capture broad regional expression patterns but miss most fine-scale differences between nearby spots. In the Visium HD colorectal cancer sections, the mean RSC of Ridge–Phikon predictions of 1,000 genes in 32-µm bins falls from 0.800 at 4,096 µm and above to 0.298 below 128 µm. The decline persists in 22 of 24 combinations of patient and bin size from 32 to 512 µm. In nine Xenium samples of breast, pancreatic and lung cancer, 10 of the 11 spot-level models that we trained have lower RSC at the finest than at the broadest scale in all nine samples.
The decline largely holds across the tested patient cohorts and image encoders. Across 70 sections from 45 patients in the nine tasks of HEST-Benchmark, Ridge–Phikon-v2 has lower RSC at the finest than at the broadest scale in 44 of 45 patients (sign-flip P < 10−6). Features from pathology foundation models raise mean RSC at all scales compared with ResNet50 features, yet the drop from the broadest to the finest scale stays between 0.31 and 0.34 for all five image encoders. Models trained on other patients miss part of the fine-scale differences that the same image features can predict within a section. When Ridge–Phikon-v2 is trained on three spatial blocks of a section and predicts the fourth block, fine-scale RSC rises from 0.152 to 0.219.
Fig. 3a RSC across spatial scales, 32-µm grid
Fig. 3b Tissue composition and sampling noise across bin sizes
Fig. 3c RSC by spatial scale and bin size
Fig. 3d 11 spot-level models in nine Xenium samples
Fig. 3e Image encoders in HEST-Benchmark
Fig. 3f Cross-patient and within-section training
| Readout | Within-section | Cross-patient | Difference (95% CI) | Patients higher | Sign-flip P |
|---|---|---|---|---|---|
| Broadest | 0.632 | 0.444 | 0.187 (0.161 to 0.215) | 44 of 45 | 5 × 10⁻⁷ |
| Broad | 0.350 | 0.257 | 0.094 (0.070 to 0.118) | 41 of 45 | 5 × 10⁻⁷ |
| Mid | 0.280 | 0.192 | 0.088 (0.066 to 0.111) | 39 of 45 | 5 × 10⁻⁷ |
| Fine | 0.231 | 0.167 | 0.064 (0.041 to 0.088) | 33 of 45 | 4 × 10⁻⁶ |
| Finest | 0.207 | 0.138 | 0.070 (0.050 to 0.090) | 41 of 45 | 5 × 10⁻⁷ |
| Fine scale (mean of Fine and Finest) | 0.219 | 0.152 | 0.067 (0.047 to 0.088) | 38 of 45 | 5 × 10⁻⁷ |
| Broad scale (mean of Broadest and Broad) | 0.491 | 0.350 | 0.141 (0.119 to 0.163) | 44 of 45 | 5 × 10⁻⁷ |
| Whole-section Pearson r | 0.323 | 0.242 | 0.081 (0.063 to 0.101) | 44 of 45 | 5 × 10⁻⁷ |
How it was computed. Fig. 3a–c is described in Methods “Scales and count transforms” and “Aggregation in colorectal cancer”, and the toolkit command strsc fourier scores physical scales on a regular grid. Fig. 3d is described in Methods “Spot-level models in HEST”, and strsc hest scores the nine Xenium samples on the 50-gene benchmark panel. Fig. 3e,f is described in Methods “Evaluation across spatial scales” and “Within-section training”, and the toolkit has no command for these HEST-Benchmark analyses.
Explore: HEST sample TENX118, spatial scales
Reproducible-signal correlation (RSC) distinguishes the most robust of three single-cell prediction methods
RSC within a cell class identifies single-cell methods that maintain fine-scale prediction quality. Within malignant cells of breast cancer sections profiled by Xenium (5 patients, nine sections), GHIST has the highest RSC of the three methods at all five scales. At the fine scale, GHIST reaches an RSC of 0.242, compared with 0.042 for DeepSpot2Cell and 0.020 for sCellST, and the split-half reliability is 0.173.
Scores across all cells or in bins are inflated by cell-type composition. Across all cells, a class-mean baseline outscores sCellST (fine-scale RSC 0.081 versus 0.036). Averaging the same predictions into 256-µm bins raises fine-scale RSC across all cells by 0.14 to 0.17 for the three methods (GHIST from 0.285 to 0.435).
Among the three methods, GHIST also locates proliferation hotspots best. Hotspots defined in one RNA half and scored in the other reach a mean enrichment of 0.976. Hotspots predicted by GHIST reach 0.335, compared with 0.101 for sCellST and −0.064 for DeepSpot2Cell.
How it was computed. python -m strsc.cell_score computes RSC within a cell class, across all cells and in bins, and the enrichment of proliferation hotspots (Methods “Evaluation within cell classes”).
Explore: Xenium breast cancer cells · all cells in bins · proliferation hotspots
Reproducible-signal correlation (RSC) reveals models locate tertiary lymphoid structures (TLS) yet poorly predict internal expression
A high AUROC for locating tertiary lymphoid structures (TLS) can overstate how well a method predicts expression inside the structures. For eight TLS-associated genes in kidney and lung cancer Visium sections, each section is predicted by Ridge–Phikon-v2 trained on the remaining sections. The predictions separate annotated TLS from immune-infiltrated, tumor and normal spots with an AUROC of 0.93 to 0.99 across sections, above the 0.61 to 0.71 of single-spot measured RNA. A class-mean baseline that predicts one value per annotated region reaches an AUROC of 0.99 to 1.00.
Between regions, the class-mean baseline reaches RSCs of 0.73 to 0.83 and Ridge–Phikon-v2 reaches 0.59 to 0.79. Within annotated TLS, the RSC of Ridge–Phikon-v2 is 0.25 to 0.29, far below the between-region values.
How it was computed. Each prediction and each RNA half is decomposed into the mean of the annotated region and the residual from the mean, and RSC is computed between regions, within regions and within TLS (Methods “Evaluation of TLS-associated genes”).
Explore: External TLS sections (Fig. 5a–f)
Training guided by reproducible-signal correlation (RSC) generally improves method performance
A pairwise difference loss that supervises expression differences between neighboring spots raises fine-scale RSC on average across models. Across the 11 spot-level models in the nine Xenium samples, the loss raises mean fine-scale RSC from 0.194 to 0.205, and the mean over the models rises in all nine samples. For Ridge–Phikon-v2 in HEST-Benchmark, the loss raises fine-scale RSC by 0.015, which is 22% of the 0.067 gain from within-section training.
Comparing neighboring spots contributes to the gain. The loss on neighboring spot pairs raises fine-scale RSC by 0.009 more than the same loss on an equal number of random non-neighboring pairs (exact sign-flip P = 0.0039), with a positive mean gain in 9 of the 11 models.
The effect of the loss depends on the analysis and the model type. The loss lowers the RSC of Ridge–Phikon-v2 between regions and within TLS and changes fine-scale RSC little for sCellST and DeepSpot2Cell.
Fig. 6a Pairwise difference loss versus standard training
Fig. 6b Change in RSC by scale
How it was computed. The loss and the model adapters are in the toolkit module strsc.training. Predictions after standard training and with the loss are scored as in Fig. 3d (Methods “Training with the pairwise difference loss”). The browser tool Pairwise difference loss trains ridge regression with and without the loss on your data.
The score table of Fig. 6c,d opens under Computed results (Score table) and downloads as neighboring-pairs-scores.csv.
Validation of reproducible-signal correlation with simulated and downsampled counts
RSC resolves individual spatial scales and separates prediction quality from sampling noise. When synthetic patterns of known scale are scored as predictions, RSC is highest at the scale of the pattern in 262 of 264 evaluable conditions, and a 90° shift of the spatial phase lowers the mean absolute RSC to 0.0012. When the true expression is scored as the prediction, RSC stays between 0.956 and 1.000 from the broadest to the finest scales, whereas the correlation with counts falls by the amount given by equation (2).
RSC stays largely stable when sampling noise increases. Downsampling the nine Xenium samples to one-eighth of the molecules lowers the fine-scale split-half reliability from 0.416 to 0.247, and whole-section Pearson r falls in all nine samples, from a mean of 0.509 to 0.408. Fine-scale RSC changes from 0.337 to 0.386. With ℓg fixed at the full-depth value, fine-scale RSC changes from 0.337 to 0.358.
Extended Data Fig. 1c True expression in three datasets
Extended Data Fig. 1d Downsampled counts in HEST
How it was computed. Extended Data Fig. 1 is described in Methods “Tests of the reproducible-signal correlation”. Panels a, b, e and f simulate Poisson or negative binomial counts in three colorectal cancer patients at eight bin sizes, and the paper contains these panels with the source data.
The source and license of each dataset are listed with the data explorers and in Supplementary Table 7 of the paper.