TABLE 1:
Characteristics of Studies Included in Review and Meta-Analysis
| First Author [Reference No.] (Year) | Lesions (Total No.) | Papillary RCC (No.) | Other Lesions (No.) | Types of Comparator Lesions (No. of Lesions) | Measurement of Interest | Cutoff Value | Sensitivity | Specificity |
|---|---|---|---|---|---|---|---|---|
| Enhancement characteristics | ||||||||
| Sun [25] (2009) | 103 | 28 | 75 | Clear cell RCC (75) | Tumor-to-cortex enhancement ratio in CMD phase | < 0.84 | 0.96 | 0.93 |
| Cornelis [24] (2014) | 100 | 16 | 84 | Clear cell RCC (57), chromophobe RCC (7), oncocytoma (16), angiomyolipoma (4) | Wil = (SIpost – SIpre) / SIpre × 100a | Wil in CMD phase < 30.9 | 0.38 | 1.00 |
| Wil in parenchymal phase < 57.9 | ||||||||
| ADC < 54.2 | ||||||||
| Pedrosa [23] (2008) | 79 | 15 | 64 | Clear cell RCC (48), chromophobe RCC (5), unclassified RCC (1), TCC (7), lymphoma (2), neuroendocrine tumor (1) | MRI classification of masses into eight descriptive categories; enhancement characterization based on qualitative appearance without specifications of the phase | Category IIIb or IVc | 0.80 | 0.94 |
| Sevcenco [27] (2014) | 50 | 15 | 35 | Clear cell RCC (29), chromophobe RCC (6) | Peak relative enhancement of tumor on any phase: relative enhancement = SIpost / SIpred | ≤ 183% | 0.93 | 0.57 |
| Chandarana [20] (2012) | 74 | 19 | 55 | Clear cell RCC (55) | Whole-lesion enhancement in CMD phase; percentage enhancement was computed on a per-voxel basis as follows: (SIpost – SIpre) / SIpre × 100d | < 100% | 0.90 | 0.96 |
| Cupido [19] (2017) | 29 | 9 | 20 | Clear cell RCC (20) | Tumor-to-cortex enhancement ratio in CMD phase | ≤ 0.55 | 1.00 | 1.00 |
| Sasiwimonphan [16] (2012)e | 81 | 16 | 65 | Clear cell RCC (49), chromophobe RCC (4), sarcomatoid RCC with unclassifiable subtype (1), mixed clear cell and papillary RCC (1), angiomyolipoma (10) | Tumor-to-cortex enhancement ratio in CMD phase | < 1.4 | 1.00 | 0.723 |
| T2 signal-intensity characteristics | ||||||||
| Oliva [22] (2009) | 49 | 21 | 28 | Clear cell RCC (28) | T2 signal intensity ratio (compared with cortex) | ≤ 0.93 | 0.952 | 0.857 |
| Cupido [19] (2017) | 33 | 9 | 24 | Clear cell RCC (20), chromophobe RCC (4) | T2 signal intensity | Low T2 signal intensity | 0.778 | 0.917 |
| Fu [4] (2016) | 83 | 11 | 72 | Clear cell RCC (67), chromophobe RCC (5) | T2 signal intensity | Low T2 signal intensity | 0.91 | 0.93 |
| Sasiwimonphan [16] (2012)e | 71 | 16 | 55 | Clear cell RCC (49), chromophobe RCC (4), sarcomatoid RCC with unclassifiable subtype (1), mixed clear cell and papillary RCC (1) | T2 signal intensity ratio (compared with cortex) | < 1.0 | 1.00 | 0.655 |
| Signal loss on opposed-phase imaging | ||||||||
| Childs [26] (2014) | 192 | 50 | 142 | Clear cell RCC (102), chromophobe RCC (4), mixed subtype (7), unclassified RCC (2), sarcomatoid clear cell (1), lymphoproliferative disorder (1), UCC (1), poorly differentiated carcinoma (1), malignant oncocytoid (1); benign lesions (22 [including 3 angiomyolipomas, 17 oncocytomas, 2 others]) | Signal loss index = [Signalin – Signalout] / Signaloutf | ≤ –0.03 | 0.48 | 0.83 |
| Yoshimitsu [17] (2006) | 66 | 9 | 57 | Clear cell RCC (57) | Signal loss ratio = [Signalin – Signalout] / Signaling | < –0.1 | 0.89 | 0.70 |
| Murray [21] (2016) | 69 | 58 | 11 | Angiomyolipoma (11) | Signal intensity index of loss = [Signalin – Signalout] / Signalout × 100h | < –16% | 0.21 | 1.00 |
| DWI | ||||||||
| Ponhold [18] (2016) | 34 | 8 | 26 | Clear cell RCC (21), chromophobe RCC (3), TCC (2) | ADC | ≤ 990 × 10−6 | 0.88 | 0.85 |
Note—RCC = renal cell carcinoma, CMD = corticomedullary, WiI = wash-in index, ADC = apparent diffusion coefficient, TCC = transitional cell carcinoma, UCC = urothelial cell carcinoma.
Where WiI is the wash-in index, SIpost is the signal intensity on contrast-enhanced images, and SIpre is the signal intensity on unenhanced images.
Category III = hemorrhagic cystic masses with peripheral enhancing projections (predicts high-grade papillary RCC).
Category IV = small homogeneous masses of low signal intensity in T2-weighted images (predicts low-grade papillary RCC).
Where SIpost is the signal intensity on contrast-enhanced images and SIpre is the signal intensity on unenhanced images.
Lesion-level data in the development set of this study can be used to calculate a 2 × 2 table for differentiating papillary RCC from other RCC subtypes and angiomyolipomas using tumor enhancement ratio and T2 signal intensity ratio. The subgroup analysis on tumor enhancement characteristics for differentiation of papillary RCC from other lesions includes minimal-fat angiomyolipoma as a type of comparator lesion. For the analysis of T2 signal-intensity characteristics for differentiation of papillary RCC from other lesions, the sensitivity and specificity presented are without angiomyolipomas in the comparator group to reduce heterogeneity among studies in this small subgroup.
Where Signalin is the signal intensity on in-phase imaging and Signalout is the signal intensity on opposed-phase imaging.
Where Signalin is the signal intensity on in-phase imaging and Signalout is the signal intensity on opposed-phase imaging.
Where Signalin is the signal intensity on in-phase imaging and Signalout is the signal intensity on opposed-phase imaging.