This work is licensed under a Table 2.
Characteristics of the 18 studies eligible for meta-analysis.
| Exclusions | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Reference | Index test(s) | Study design | Population | HU (HU) | Size (mm) | Other | Pat./Les. (N) | I/KM/S (%) | HE (%) | Reference standard (%) | Dis n; % | No. ACC | No. mets | Threshold for malignancy |
| Studies investigating incidentally detected tumors (n=7) | ||||||||||||||
| Angelelli (2013) | CT | BPCP | Imaging series, ≥50% incidental | No | <10, >120 | Cysts, myelolipoma | 50/50 | 74/0/26 | NR | 42/58/0 | 28; 56% | 7 | 13 | 1. >10 HU2. APW <60% OR RPW <40% at 10′3. APW <60% OR RPW <40% at 15′ |
| Marin (2012) | MRI | NCR | Imaging series, ≥90% incidental | No | <10 | No | 59/66 | 100/0/0 | NR | 35/55/11 | 17; 26% | 5 | 11 | 1. SII ≤23% (OP/IP dataset)‖ |
| Maurea (2004) | MRI | NCP | Imaging series, ≥50% incidental | NR | NR | Functioning masses; Pheos (n=4) excluded by Bham team | 30/30 | 66/33/0 | 0 | 63/37/0 | 8; 31% | 4 | 3 | 1. ALR – qualitative*2. SI – qualitative‡ |
| Nunes (2010) | PET | WPCR | Imaging series, ≥50% incidental | <10 | NR | Pheos; prior cancer; ACC on CT; eventual washout of contrast >50% on CT | 23/23 | 65/0/35 | 43 | 100/0/0 | 3; 13% | 2 | 0 | 1. ALR SUVmax >1.6§2. SUVmax >3.4 |
| Sandra-segaran (2011) | MRI | NCR | Imaging series, ≥50% incidental | No | <10 | Myelolipoma; cysts; artifacts on diffusion weighted imaging; lack of adequate reference | 48/49 | 69/31/0 | 2 | 38/63/0 | 12; 24% | 1 | 9 | 1. ASR≥62 (ADC)¶2. SII ≤ 23% (ADC)‖ |
| Tessonier (2008) | PET | WPCP | Imaging series, ≥90% incidental | <10 | No | Functioning masses; washout on delayed enhanced CT, decrease of signal intensity on CS MRI | 37/41 | 100/0/0 | 0 | 71/29/0 | 12; 29% | 3 | 4 | 1. ALR SUVmax >1.8§2. SUVmax >3.28 |
| Vilar (2008) | CT | NCR | Imaging series, ≥90% incidental | NR | NR | None reported | 52/52 | 100/0/0 | 25% | 38/40/17 | 13; 25% | 2 | 5 | 1. >10 HU |
| Studies investigating tumors in participants with current or prior non-adrenal malignancy (n=11) | ||||||||||||||
| Burt (1994) | MRI | NCP | Operable NSCLC, ≥90% known malignancy | NR | No | None reported | 27/27 | 0/100/0 | NR | 100/4/0 | 4; 16% | 0 | 5 | 1. ALR qualitative* |
| Choi (2013) | CT | WPCR | Imaging series, ≥90% known malignancy | No | No | All diagnoses other than adenoma and metastasis | 36/40 | 0/100/0 | NR | 100/30/0 | 19; 48% | 0 | 19 | 1. >10 HU2. APW at 15′ <60%3. RPW at 15′ <40% |
| Del Moral (2010) | PET–CT | NCR | Imaging series, ≥50% known malignancy | NR | NR | Symptomatic tumors; Contraindications to PET; | 15/15 | 0/53/47 | NR | 87/13/0 | 11; 73% | 3 | 5 | 1. ALR SUVmax >1.8§2. SUVmax >6 |
| Frilling (2004) | CT | WPCP | Adrenalectomy series, ≥90% known malignancy | No | ≤60 | Evidence of extra-adrenal tumor spread | 42/44 | 0/100/0 | 0 | 100/0/0 | 31; 70% | 0 | 31 | >10HU |
| Kunik-owska (2014) | PET-CT | WPCR | Imaging series, ≥90% known malignancy | No | No | Functioning masses | 85/104 | 0/100/0 | NR | 100/0/0 | 32; 31% | 1 | 30 | 1. ALR SUVmax >1.53§2. SUVmax >5.2 |
| Lang (2015) | PET-CT | NCR | Adrenalect-omy series, ≥90% known malignancy | No | No | Functioning masses; no clinical suspicion of metastasis (based on CT findings) | 39/39 | 0/100/0 | 0 | 100/0/0 | 29; 74% | 0 | 28 | 1. ALR SUVmax >1.29§2. SUVmax >3.7 |
| Mc-Nicholas (1995) | CTMRI | WPCP | Imaging series, ≥90% known malignancy | NR | <10 | Pheos | 33/37 | 0/100/0 | NR | 51/46/0 | 19; 51% | 0 | 18 | CT: >10HUMRI: ASR ≥75¶ |
| Porte (1999) | CTMRI | WPCP | Operable NSCLC, ≥90% known malignancy | NR | <10 | Pheos | 32/32 | 0/100/0 | NR | 100/44/0 | 18; 56% | 0 | 18 | CT: >10HUMRI: ALR qualitative† |
| Ream (2014) | MRI | NCR | Imaging series, ≥50% known malignancy | No | <8 | Myelolipoma; cysts; non-standardized imaging protocol; lack of adequate reference | 36/37 | NR/78/NR | NR | 19/76/5 | 10; 28% | 0 | 8 | 1. ALR >0.674††2. ASR >64.1‡‡3. AMR >70.7§§ |
| Schwartz (1995) | MRI | NCP | Biopsy referrals, ≥90% known malignancy | NR | NR | None reported | 68/68 | 0/100/0 | NR | 71/29/0 | 23; 34% | NR | NR | 1. ALR ≥1.5**2. ASR ≥55¶ |
| Uemura (2012) | CT | WPCR | Imaging series, ≥90% known malignancy | NR | NR | Grades 4 or 5 disease; bleeding tendency and coagulopathy | 12/16 | 0/100/0 | NR | 93/0/7 | 6; 40% | 0 | 6 | 1. >10HU |
ACC, adrenocortical carcinoma; BPC, between-person comparison (multiple index tests evaluated in partial study population); APW, absolute percentage washout; ADC, apparent diffusion coefficient; ALR, adrenal to liver ratio; ASR, adrenal to spleen ratio; AMR, adrenal to muscle ratio; ASR, adrenal to spleen ratio; CS, chemical shift; Excl, exclusion; HU, Hounsfield units; IP, in-phase; METS, metastases; NC, non-comparative study; NR, not reported; NSCLC, non-small cell lung cancer; OP, opposed phase; P, prospective data collection; R, retrospective data collection; RPW, relative percentage washout; SI, signal intensity; SII, signal intensity index; SUVmax, maximum standardized uptake value; WPC, within-person comparison (multiple index tests evaluated in all study participants).
Masses considered to be malignant if their signal was more intense than liver signal
Masses considered to be metastases if their signal was more intense than liver signal and inferior to kidney signal
Masses considered to be malignant if no loss of signal intensity observed on chemical shift
ALR SUVmax, ratio of SUVmax in the adrenal gland compared with the liver.
Formulae for calculating quantitative thresholds:
Signal intensity index =[(SI adrenal IP) – (SI adrenal OP)] / (SI adrenal IP)
MRI adrenal to spleen ratio=(SI adrenal OP/SI Spleen OP)/(SI adrenal IP/SI spleen IP)
MRI adrenal to liver ratio=SI adrenal/SI liver
MRI adrenal to liver ratio=[(SI adrenal OP/SI liver OP)/(SI adrenal IP/SI liver IP)] – 1) × 100%
MRI adrenal to spleen ratio=[(SI adrenal OP/SI spleen OP)/(SI adrenal IP/SI spleen IP)] – 1)×100%
MRI adrenal to muscle ratio=[(SI adrenal OP/SI muscle OP)/(SI adrenal IP/SI muscle IP)] – 1)×100%].