Impact of the integration of proton magnetic resonance imaging spectroscopy to PI-RADS 2 for prediction of high grade and high stage prostate cancer

Leapman, Michael S.; Wang, Zhen J.; Behr, Spencer C.; Kurhanewicz, John; Zagoria, Ronald J.; Carroll, Peter R.; Westphalen, Antonio C.

doi:10.1590/0100-3984.2016.0117

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Original Article • Radiol Bras 50 (5) • Sep-Oct 2017 • https://doi.org/10.1590/0100-3984.2016.0117 copy

Impact of the integration of proton magnetic resonance imaging spectroscopy to PI-RADS 2 for prediction of high grade and high stage prostate cancer

Impacto da incorporação da espectroscopia por ressonância magnética ao PI-RADS 2 para a predição de câncer de próstata de alto grau e de estágio avançado

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Objective:

To compare the predictions of dominant Gleason pattern ≥ 4 or non-organ confined disease with Prostate Imaging Reporting and Data System (PI-RADS v2) with or without proton magnetic resonance spectroscopic imaging (¹H-MRSI).

Materials and Methods:

Thirty-nine men underwent 3-tesla endorectal multiparametric MRI including ¹H-MRSI and prostatectomy. Two radiologists assigned PI-RADS v2 and ¹H-MRSI scores to index lesions. Statistical analyses used logistic regressions, receiver operating characteristic (ROC) curves, and 2x2 tables for diagnostic accuracies.

Results:

The sensitivity and specificity of ¹H-MRSI and PI-RADS v2 for high-grade prostate cancer (PCa) were 85.7% (57.1%) and 92.9% (100%), and 56% (68.0%) and 24.0% (24.0%). The sensitivity and specificity of ¹H-MRSI and PI-RADS v2 for extra-prostatic extension (EPE) were 64.0% (40%) and 20.0% (48%), and 50.0% (57.1%) and 71.4% (64.3%). The area under the ROC curves (AUC) for prediction of high-grade prostate cancer were 0.65 and 0.61 for PI-RADS v2 and 0.72 and 0.70 when combined with ¹H-MRSI (readers 1 and 2, p = 0.04 and 0.21). For prediction of EPE the AUC were 0.54 and 0.60 for PI-RADS v2 and 0.55 and 0.61 when combined with ¹H-MRSI (p > 0.05).

Conclusion:

¹H-MRSI might improve the discrimination of high-grade prostate cancer when combined to PI-RADS v2, particularly for PI-RADS v2 score 4 lesions, but it does not affect the prediction of EPE.

Keywords:
MRI; Spectroscopy; Diagnosis; Prostate cancer; Prostatectomy

	Reader 1		Reader 2
Sequence	N	(%)	N	(%)
T2W – Peripheral zone
1 – Uniform hyperintense signal intensity (normal)	0	(0)	0	(0)
2 – Linear or wedge-shaped hypointensity/diffuse mild hypointensity, usually indistinct margin	1	(3.5)	0	(0)
3 – Heterogenous signal intensity or non-circumscribed rounded, moderate hypointensity	11	(37.9)	5	(19.3)
4 – Circumscribed, homogenous moderate hypointense focus/mass confined to prostate and < 1.5 cm in greatest dimension	14	(48.3)	11	(42.3)
5 – As above, but ≥ 1.5 cm in greatest dimension or definitive extra-prostatic extension/invasive behavior	3	(10.3)	10	(38.5)
T2W – Transition zone
1 – Homogeneous intermediate signal intensity (normal)	0	(0)	0	(0)
2 – Circumscribed hypointense or heterogeneous encapsulated nodule(s) (benign prostatic hyperplasia)	0	(0)	0	(0)
3 – Heterogeneous signal intensity with obscured margins; includes others that do not qualify as 2, 4, or 5	1	(12.5)	1	(10.0)
4 – Lenticular or non-circumscribed, homogeneous, moderately hypointense, and < 1.5 cm in greatest dimension	2	(25.0)	1	(10.0)
5 – As above, but ≥ 1.5 cm in greatest dimension or definite extraprostatic extension/invasive behavior	5	(62.5)	8	(80.0)
DWI
1 – No abnormality	2	(5.1)	3	(7.7)
2 – Indistinct hypointensity on ADC	0	(0)	0	(0)
3 – Focal mildly/moderately hypointense on ADC and isointense/mildly hyperintense on high b-value DWI	4	(10.3)	8	(20.5)
4 – Focal markedly hypointense on ADC and markedly hyperintense on high b-value DWI; < 1.5 cm in greatest dimension	23	(59.0)	12	(30.8)
5 – As above, but ≥ 1.5 cm in greatest dimension or definite extraprostatic extension/invasive behavior	10	(25.6)	16	(41.0)
DCE
(–) No early enhancement; or diffuse enhancement not corresponding to a focal finding on T2 and/or DWI; or focal enhancement corresponding to a lesion demonstrating features of benign prostatic hyperplasia on T2WI	11	(28.2)	14	(35.9)
(+) focal, and; earlier than contemporaneously with enhancement of adjacent normal prostate tissue, and; corresponds to suspicious finding on T2W and/or DWI	28	(71.8)	25	(64.1)
Overall score
1 – Very low (clinically significant cancer is highly unlikely to be present)	0	(0)	0	(0)
2 – Low (clinically significant cancer is unlikely to be present)	2	(5.1)	3	(7.7)
3 – Intermediate (the presence of clinically significant cancer is equivocal)	5	(12.8)	3	(7.7)
4 – High (clinically significant cancer is likely to be present)	23	(59.0)	16	(41.0)
5 – Very high (clinically significant cancer is highly likely to be present)	9	(23.1)	17	(43.6)
¹H MRSI
1 – Citrate:choline ratio ≥ 2	3	(7.7)	3	(7.7)
2 – Citrate:choline ratio 1–2	5	(12.8)	8	(20.5)
3 – Choline=citrate	8	(20.5)	12	(30.8)
4 – Choline:citrate ratio 1–2	22	(56.4)	13	(33.3)
5 – Choline:citrate ratio ≥ 2	1	(2.6)	3	(7.7)

Variable	Statistic
Age at diagnosis, median (IQR, range)	65 (11, 45–75)
PSA, ng/ml, median (IQR, range)	6.8 (5.1, 1.62–16)
PSA density, median (IQR, range)	0.20 (0.15, 0.06–0.65)
Clinical stage (digital rectal examination), N (%)
T1c	11 (28.2)
T2a	25 (64.1)
T2b	1 (2.6)
T3a	1 (2.6)
T3b	1 (2.6)
Diagnosis biopsy Gleason grade, N (%)
3+3	9 (23.1)
3+4	19 (48.7)
4+3	8 (20.5)
4+4	1 (2.6)
5+4	1 (2.6)
5+5	1 (2.6)
Number of diagnostic cores taken, median (IQR, range)	15 (5, 6–24)
Percentage of positive diagnostic cores, median (IQR, range)	25 (29, 8–50)
CAPRA score, %
0–2 (low risk)	13 (33.3)
3–5 (intermediate risk)	21 (53.9)
6–10 (high risk)	5 (12.8)

	Sensitivity (95% CI)	Specificity (95% CI)	PPV (95% CI)	NPV (95% CI)
High grade prostate cancer (dominant Gleason pattern ≥ 4)
		Reader 1
Overall PI-RADS 2	92.9 (66.1-99.8)	24.0 (9.4-45.1)	40.6 (23.7-59.4)	85.7 (42.1-99.6)
¹H MRSI	85.7 (57.2-98.2)	56.0 (34.9-75.6)	52.2 (30.6-73.2)	87.5 (61.7-98.4)
		Reader 2
Overall PI-RADS 2	100.0 (76.8-100)	24.0 (9.4-45.1)	42.4 (25.5-60.8)	100.0 (54.1-100)
¹H MRSI	57.1 (28.9-82.3)	68.0 (46.5-85.1)	50.0 (24.7-75.3)	73.9 (51.6-89.8)
Extraprostatic disease (stage ≥ T3a)
		Reader 1
Overall PI-RADS 2	20.0 (6.8-40.7)	71.4 (41.9-91.6)	55.6 (21.2-86.3)	33.3 (17.3-52.8)
¹H MRSI	64.0 (42.5-82.0)	50.0 (23.0-77.0)	69.6 (47.1-86.8)	43.8 (19.8-70.1)
		Reader 2
Overall PI-RADS 2	48.0 (27.8-68.7)	64.3 (35.1-87.2)	70.6 (44.0-89.7)	40.9 (20.7-63.6)
¹H MRSI	40.0 (21.1-61.3)	57.1 (28.9-82.3)	62.5 (35.4-84.8)	34.8 (16.4-57.3)

	Reader 1		Reader 2
Model variables	AUC	95% CI	AUC	95% CI
Dominant Gleason pattern 4 or higher outcome
Overall PI-RADS 2	0.65	0.49-0.81	0.61	0.45-0.77
¹H MRSI	0.75	0.62-0.87	0.70	0.55-0.86
Overall PI-RADS 2 + ¹H MRSI	0.77	0.63-0.91	0.70	0.53-0.86
Pathological stage T3a or higher outcome
Overall PI-RADS 2	0.54	0.34-0.73	0.60	0.42-0.78
¹H MRSI	0.61	0.43-0.79	0.54	0.36-0.73
Overall PI-RADS 2 + ¹H MRSI	0.55	0.34-0.76	0.61	0.43-0.80

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[1] Mailing address: Antonio C. Westphalen, MD, PhD. Department of Radiology and Biomedical Imaging, University of California San Francisco. 505 Parnassus Avenue, M-372 San Francisco, CA, 94143, USA. E-mail: antonio.westphalen@ucsf.edu.