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. 2020 Nov 19;27(1):134–146. doi: 10.5152/dir.2020.19515

Table 1.

Modifications and methods of MRU for diagnosing urethral stricture disease

Study n Age (y) Techniques Location Cause of the stricture MRI unit Exam protocol Points of evaluation Reference Mean stricture length Aim of the study Results/Additional remarks
Dixon et al. 1992 18 4–71 MRI Posterior Trauma 1.5 T (n=11) 0.35 T (n=5) 11 examinations:

  1. Tra T1WI (TR / TE 500 / 20 ms)

  2. Tra Sag Cor T2WI (TR / TE 2500 / 70–80 ms)

  3. Tra Sag Cor PD (TR / TE 2500 / 30 ms; section thickness 4 mm, matrix 192× 256)

5 examinations:

  1. Tra T1WI (TR / TE 500 / 30 ms)

  2. Tra Sag Cor T2WI (2000 / 60 ms; slice thickness 5 mm, matrix 256× 256)

 Length of injury; Displacement of prostate in 3 planes; Pelvic bone fracture Surgery No data To examine the role of MRI in post-traumatic pelvic anatomy Optimizing surgical treatment MRI can determine the length of urethral defect and severity of prostatouretheral dislocation
Narumi et al. 1993 27 (+ 1 HC) 4–71 MRI Posterior Trauma 1.5 T (n=23)
0.35 T (n=5)		 23 examinations (22 patients, 1 HC):

  1. Tra T1WI (TR / TE 500 / 20 ms)

  2. Tra Sag Cor T2WI (2500 / 70–80 ms)

  3. Tra Sag Cor PD (2500 / 30 ms; section thickness 4 mm, matrix 192× 256)

  4. 3 patients - T2WI FSE (3800– 4500 / 96–106 ms; slice thickness 4 mm, matrix 512× 256)

5 examinations:

  1. Tra T1WI (TR / TE, 500 / 30 ms)

  2. Tra Sag Cor T2WI (2000 / 60 ms; slice thickness 5 mm, matrix 256× 256)

 Length of injury; Displacement of prostate in 3 plane;s Presence and type of penile injury; Pelvic bone fracture Surgery No data To examine the role of MRI in preoperative evaluation of posterior urethral injury; To evaluate the role of MRI in predicting permanent erectile dysfunction after posterior urethral injury Length of the injury measured correctly in 85% cases. Displacement of the prostate apex in 90% patients. MRI findings caused alteration in surgical procedure in 7 (26%) patients
Yekeler et al. 2004 18 (12 with strictures, 5 healthy controls) 43.3 (22–90) 3D MRVU vs. RUG (n=10) and urethroscopy (n=12) Anterior (n=7), posterior (n=7) Urinary bladder cancer (n=1), Prostatic hypertrophy (n=5), Unknown (n=12) 1.5 T

  1. Cor and HASTE (TR / TE, l/82 ms; matrix, 75× 256; FOV 300× 180 mm; slice thickness, 6 mm; gap, 0.6 mm)

  2. Sag T1WI 3D FLASH (3.2/1.1 ms; flip angle, 308; slab thickness, 94–112 mm; slice thickness, 1 mm; FOV, 300× 180 mm; matrix, 300–320× 512; acquisition time, 35 s)

  3. Cor T1WI 3D FLASH (3.2/1.1 ms; flip angle, 308; slab thickness, 72 mm; slice thickness, 1 mm; FOV, 300× 180 mm; matrix, 300–320×512; acquisition time, 24 s)*

  4. MRVU Sag T1WI 3D FLASH (3.2/1.1 ms; flip angle, 308; slab thickness, 44 mm; slice thickness, 1 mm; FOV 300× 80 mm; matrix 300– 320× 512; acquisition time, 15 s). 3 consecutive acquisitions (0, 15 and 30 s) and to evaluate bladder residual volume.

  5. 4-element phased-array body coil

  6. *6-channel phased-array spine coil

  7. Voiding before MRI

  8. 0.3 mL/ kg Gd-DTPA prior to CE 3D MRVU

  9. Readiness to urinate 55–170 min (mean, 70 min) post i.v. contrast injection

 Stricture number and length Urethroscopy; 5 healthy volunteers for anatomy outline [cm] RUG: 2.4 (0.7–3.2) MRI: 2.1 (0.5–3.1) To assess the feasibility of CE MRVU with the use of the CE 3D MRA technique in healthy volunteers and in patients with urethral strictures Severe membranous urethral strictures better demonstrated by CE 3D MRVU. CE 3D MRVU superior to RUG in demonstration of normal urethra in the proximal junction of strictures in patients with membranous and bulbous urethral strictures
Osman et al. 2006 20 55±19 (17–77) MRI vs. RUG+VCUG Anterior and posterior Postinflammatory (n=16), Iatrogenic injury (n=2), Trauma (n=2) No data

  1. Sag high-resolution T2WI (TR/TE 4000–6000/80–120 ms, slice thickness 2 mm, gap 0 mm).

  2. Reformatted images at axial, coronal, and sagittal oblique planes

  3. Sterile gel

 Entire urethra; Surrounding soft tissues; Periurethral fibrosis; Stricture length Urethroscopy followed by definitive endoscopic or open operative intervention [cm] RUG + VCUG: 1.5±1.3 MRI: 1.2±0.9 To compare clinical relevance of RUG~ and MRU in male urethral strictures MRI findings caused alteration on surgical procedure in at least 4 patients. No difference in stricture length between the modalities (p = 0.25). Same accuracy for diagnosis of urethral strictures (85%). MRU provided extra clinical data in 7 patients (35%). MRU superior to RUG in evaluating surrounding tissues. MRU provided adequate information about the degree of spongiofibrosis in all patients.
Sung et al. 2006 12 48.4 (21–83) MRI vs. RUG+VCUG Anterior and posterior Radical prostatectomy (n=1). Trauma (n=11) 1.5T

  1. Sag T2WI FSE (TR/TE 3000/99 ms)

  2. Tra T2WI FSE (3200/99 ms; FOV, 24 cm; matrix, 512× 264; section thickness 3 mm; gap 0.1 mm)

    150–300 mL of saline injected into the emptied bladder through the suprapubic cystostomy + 8–10 mL of sterile gel

  3. Sag T2WI FSE (3000/99 ms)

  4. Tra T2WI FSE (3200/99 ms; FOV 24 cm; matrix, 512× 264; section thickness 3 mm; gap 0.1 mm)

  5. Sag T1WI SE (473/20 ms)

  6. Sag T1WI SE (473/20 ms) post 0.1 mmol/kg Gd-DTPA (3 min)

  7. Pelvic phased-array coil

  8. Distention of urethra with saline

 Signal intensity, location, length, and contrast enhancement of the stricture; Urethra proximal to the stricture; Corpora spongiosa; Adjacent organ injuries Surgical specimen or a report on surgical findings No data To evaluate MRU for the depiction of obliterative urethral strictures; To compare the accuracy of MRU versus VCUG in estimating the length of obliterative urethral stricture MRI findings caused the change in surgical procedure in 7 of the 10 patients. Stricture length overestimated in 58% patients in MR and 60% in RUG + VCUG. Mean measurement error at MRI significantly lower than in RUG + VCUG. Stronger linear relationship between MRI and surgical measurements
Koraitim et al. 2007 21 6–35 MRI vs. RUG+VCUG Posterior Trauma 0.2 T

  1. Tra Sag T1WI FSE (TR/TE 690/15 ms; slice thickness 5 mm)

  2. Tra Sag T2WI FSE (3400–4000/ 106 ms; slice thickness 4 mm)

  3. Sag T2WI FSE with fat suppression (3400–4000/ 106 ms; slice thickness 4 mm)

  4. Cor T2WI FSE (3400–4000/ 106 ms; slice thickness 4 mm)

 Urethral distraction; Associated injuries Surgery No data To determine clinical usefulness of MRI in assessment of posterior urethral distraction defects; To determine if MRI can identify the cause of posttraumatic impotence Length of urethral defect and type of prostatic displacement could be correctly determined in MRI in 86% and 89% of the patients, respectively
El-ghar et al. 2010 30 45±18 (15–75) MRI vs. RUG+SUG Anterior and posterior No data No data

  1. Sag high-resolution T2WI (TR/TE 4000–6000/80–120 ms, slice thickness 2 mm, gap 0 mm)

  2. Reformatted images at axial, coronal, and sagittal oblique planes

  3. Sterile gel

 Stricture length; Associated pathology; Abnormal communication Surgery [mm]
RUG: 13.3±5.7 (3–24)
SUG: 11.2±4.9 (3–20)
MRI: 11.4 (3–20)
Surgery: 11.3 (3–20)		 To compare the accuracy of MRU versus combined RUG and SUG in diagnosis of urethral stricture with evaluation of their impact on management choice MRU comparable with RUG+SUG in diagnosing the anterior and posterior urethral strictures regarding the site and extension and degree of spongiofibrosis but MRU is superior in diagnosis of associated pathologies with stricture
Oh et al. 2010 25 48.7 (21–72) MRI vs. RUG+VCUG Posterior Trauma (n=24), Radical prostatectomy (n=1) 1.5T

  1. Sag T2WI FSE (TR/TE 3000/99)

  2. Tra T2WI FSE (3200/99, FOV 24 cm, matrix 512×264, slice thickness 3 mm, gap 0.1 mm)

  3. Sag T1WI SE (473/20) 4. Sag T1WI SE post 0.1 mmol/kg Gd-DTPA (3 min delay)

  4. Pelvic phased-array coil

  5. Sterile gel

  6. Emptied bladder filled with 200–300 mL saline through the suprapubic catheter until need to void

 Stricture length Surgery [cm]
RUG + VCUG (n=22): 2.3
MRI: 1.56
Surgery: 1.51		 To evaluate the role of MRU in depicting obliterative urethral stricture Mean SD measurement error in MRU significantly less than that RGU + VCUG (0.4±0.4 vs. 1.4±1.1 cm, p < 0.001). Stronger linear relationship between MRU and surgical measurements (r2=0.62, p <0.01.
Park et al. 2010 10 61.7 (47–77) SSFSE MRU vs. FRFSE MRU vs. RUG Anterior TURP (n=4), Laser surgery of the prostate (n=2), Trauma (n=4) 1.5 T

  1. Sag T2WI TS-SSFSE (TR/TE 4595–4699/176 ms, slice thickness 20 mm, gap 0 mm, matrix 512×448)

  2. Sag T2WI FRFSE (TR 2900–3367 ms/TE 100 ms; slice thickness 3 mm, gap 0 mm, matrix 512×256)

  3. Sterile gel

 Location, type, length and internal diameter of the stricture; MRI image quality MRU [mm]
MRI:
1. TS-SSFSE 36.4± 21.8 (4.0–71.3)
2. FRFSE 35.7± 20.8 (4.0–67.5)
Surgery (n=8): 18.8± 4.8 (15–25)
Internal diameter:
1. TS-SSFSE 0.73± 0.80 (0–1.8) mm
2. FRFSE 0.77± 0.74 (0–2.1) mm		 To determine the role of TS-SSFSE vs. FRFSE for evaluating anterior urethral stricture TSSSFSE MRU can provide useful information on anterior urethral strictures; it allows obtaining a RUG-like image during an ultra-short scan time. TSSSFSE MRU may not be sensitive enough to detect sophisticated periurethral changes due to inferior mage quality
Khalaf et al. 2015 20 49.6± 16.4 (19–70) MRI vs. RUG Anterior No data 1.0T

  1. Sag T1WI FSE (TR/TE 400/20)

  2. Sag T2WI FSE (3000/99)

  3. Tra T2WI FSE (3200/99 ms; FOV 24 cm; matrix 512×264; thickness 3 mm; gap 0.1 mm)

  4. Pelvic phased-array coil

  5. Sterile gel

 Signal intensity, location and length of the stricture; Urethra proximal to the stricture; Corpora spongiosa; Adjacent organ injuries; Associated complications Surgery [cm]
RUG: 1.75±1.02/
MRI: 1.32±0.85
Surgery: 1.29±0.83		 To evaluate diagnostic capability of MRU vs. conventional RUG in anterior urethral stricture Accuracy of MRU 95%
Hanna et al. 2015 18 37.37 (13–61) MRI vs. RUG Anterior and posterior Trauma (n=13), Congenital (n=3), Postinflammatory (n=2) 1.5 T

  1. Sag T2WI TSFSE (TR 4500–4700 ms, TE 176 ms, thickness 20 mm, gap 0 mm)

  2. Sag T2WI FRFSE (TR 2900–3300 ms, TE 100 ms, thickness 3 mm, gap 0 mm)

  3. Reformatted images at different planes

  4. Pelvic phased-array coil

  5. Sterile gel 16 pts

  6. Sterile water 2 pts

 Stricture length; Associated pathology No data No data To evaluate utility of MRU vs. conventional urethrography in diagnosis and characterization of different urethral lesions MRU superior in delineation and characterization of the urethral pathology in four cases (22.2%), diagnosing prostatic displacement as well as periurethral fibrosis, inferior in diagnosing a case of diffuse pseudodiverticulosis
Rastogi et al. 2016 20 18–72 MRI vs. SUG N/A Postinflammatory (n=10), Trauma (n=3), Iatrogenic (n=3), Idiopathic (n=1), Excluded (n=3) 1.5 T No data on exam protocol

  1. Sterile gel

 No data No data No data To evaluate the comparative role of SUG and MRU in the evaluation of male anterior urethral strictures MRU findings caused alteration in surgical procedure in 1 patient
Pandian et al. 2017 20 34 (17–61) MRI vs. RUG+VCUG Posterior Trauma 3.0T

  1. Tra Sag Cor T2WI

  2. STIR_Long TR/RA, SS-TSE, SPAIR, SENSE. TR 3500ms/TE 90 ms; slice thickness 3 mm

  3. Sterile gel

 Urethral distraction; Associated injuries Surgery No data To establish if MRI provides additional information for preoperative planning. To assess the role of MRI in counseling and management of PFUDD. MRI provides detailed 3D images of urethral distraction defect

All studies were prospective except for Rastogi et al., in which the design was not specified.

Patients with multiple strictures were clearly identified only in Yekeler et al. (14 strictures in 12 patients).

Osman et al., El Gahr et al., and Khalaf et al. defined short stricture as <1.5 cm, long stricture as >1.5 cm. Park et al. defined short stricture as <2.5 cm, long stricture as >2.5 cm. Sung et al. defined short stricture as <1.0 cm, intermediate stricture as 1.0–2.5 cm, long stricture as >2.5 cm.

MRI, magnetic resonance imaging; Tra, transverse; T1WI, T1-weighted image; TR, time of repetition; TE, time of echo; Sag, sagittal; Cor, coronal; PD, proton density; MRVU, magnetic resonance voiding urethroghraphy; RUG, retrograde uretrography, TSE, turbo spin-echo; FOV, field of view; 3D, three dimensional; Gd-DTPA, gadopentate dimeglumine; CE, contrast enhanced; i.v., intravenous; VCUG, voiding cystourethrography; SUG, sonourethrography; TURP, transurethral resection of prostate; FSE, fast spin-echo; SSFSE, thick slab single-shot fast spin echo; FRFSE, fast recovery fast spin echo; STIR, short T1 inversion recovery; SPAIR, SPectral Attenuated Inversion Recovery, SENSE, SENSitivity Encoding; HASTE, half-fourier single shot turbo spin-echo; TS-SSFSE, thick slab single-shot fast spin-echo; SS-TSE, single-shot turbo spin-echo; PFUDD, posterior pelvic fracture urethral distraction defect.