- •Contents
- •Contributors
- •1 Introduction
- •2.1 Posterior Compartment
- •2.2 Anterior Compartment
- •2.3 Middle Compartment
- •2.4 Perineal Body
- •3 Compartments
- •3.1 Posterior Compartment
- •3.1.1 Connective Tissue Structures
- •3.1.2 Muscles
- •3.1.3 Reinterpreted Anatomy and Clinical Relevance
- •3.2 Anterior Compartment
- •3.2.1 Connective Tissue Structures
- •3.2.2 Muscles
- •3.2.3 Reinterpreted Anatomy and Clinical Relevance
- •3.2.4 Important Vessels, Nerves, and Lymphatics of the Anterior Compartment
- •3.3 Middle Compartment
- •3.3.1 Connective Tissue Structures
- •3.3.2 Muscles
- •3.3.3 Reinterpreted Anatomy and Clinical Relevance
- •3.3.4 Important Vessels, Nerves, and Lymphatics of the Middle Compartment
- •4 Perineal Body
- •References
- •MR and CT Techniques
- •1 Introduction
- •2.1 Introduction
- •2.2.1 Spasmolytic Medication
- •2.3.2 Diffusion-Weighted Imaging
- •2.3.3 Dynamic Contrast Enhancement
- •3 CT Technique
- •3.1 Introduction
- •3.2 Technical Disadvantages
- •3.4 Oral and Rectal Contrast
- •References
- •Uterus: Normal Findings
- •1 Introduction
- •References
- •1 Clinical Background
- •1.1 Epidemiology
- •1.2 Clinical Presentation
- •1.3 Embryology
- •1.4 Pathology
- •2 Imaging
- •2.1 Technique
- •2.2.1 Class I Anomalies: Dysgenesis
- •2.2.2 Class II Anomalies: Unicornuate Uterus
- •2.2.3 Class III Anomalies: Uterus Didelphys
- •2.2.4 Class IV Anomalies: Bicornuate Uterus
- •2.2.5 Class V Anomalies: Septate Uterus
- •2.2.6 Class VI Anomalies: Arcuate Uterus
- •2.2.7 Class VII Anomalies
- •References
- •Benign Uterine Lesions
- •1 Background
- •1.1 Uterine Leiomyomas
- •1.1.1 Epidemiology
- •1.1.2 Pathogenesis
- •1.1.3 Histopathology
- •1.1.4 Clinical Presentation
- •1.1.5 Therapy
- •1.1.5.1 Indications
- •1.1.5.2 Medical Therapy and Ablation
- •1.1.5.3 Surgical Therapy
- •1.1.5.4 Uterine Artery Embolization (UAE)
- •1.1.5.5 Magnetic Resonance-Guided Focused Ultrasound
- •2 Adenomyosis of the Uterus
- •2.1 Epidemiology
- •2.2 Pathogenesis
- •2.3 Histopathology
- •2.4 Clinical Presentation
- •2.5 Therapy
- •3 Imaging
- •3.2 Magnetic Resonance Imaging
- •3.2.1 Magnetic Resonance Imaging: Technique
- •3.2.2 MR Appearance of Uterine Leiomyomas
- •3.2.3 Locations, Growth Patterns, and Imaging Characteristics
- •3.2.4 Histologic Subtypes and Forms of Degeneration
- •3.2.5 Differential Diagnosis
- •3.2.6 MR Appearance of Uterine Adenomyosis
- •3.2.7 Locations, Growth Patterns, and Imaging Characteristics
- •3.2.8 Differential Diagnosis
- •3.3 Computed Tomography
- •3.3.1 CT Technique
- •3.3.2 CT Appearance of Uterine Leiomyoma and Adenomyosis
- •3.3.3 Atypical Appearances on CT and Differential Diagnosis
- •4.1 Indications
- •4.2 Technique
- •Bibliography
- •Cervical Cancer
- •1 Background
- •1.1 Epidemiology
- •1.2 Pathogenesis
- •1.3 Screening
- •1.4 HPV Vaccination
- •1.5 Clinical Presentation
- •1.6 Histopathology
- •1.7 Staging
- •1.8 Growth Patterns
- •1.9 Treatment
- •1.9.1 Treatment of Microinvasive Cervical Cancer
- •1.9.2 Treatment of Grossly Invasive Cervical Carcinoma (FIGO IB-IVA)
- •1.9.3 Treatment of Recurrent Disease
- •1.9.4 Treatment of Cervical Cancer During Pregnancy
- •1.10 Prognosis
- •2 Imaging
- •2.1 Indications
- •2.1.1 Role of CT and MRI
- •2.2 Imaging Technique
- •2.2.2 Dynamic MRI
- •2.2.3 Coil Technique
- •2.2.4 Vaginal Opacification
- •2.3 Staging
- •2.3.1 General MR Appearance
- •2.3.2 Rare Histologic Types
- •2.3.3 Tumor Size
- •2.3.4 Local Staging
- •2.3.4.1 Stage IA
- •2.3.4.2 Stage IB
- •2.3.4.3 Stage IIA
- •2.3.4.4 Stage IIB
- •2.3.4.5 Stage IIIA
- •2.3.4.6 Stage IIIB
- •2.3.4.7 Stage IVA
- •2.3.4.8 Stage IVB
- •2.3.5 Lymph Node Staging
- •2.3.6 Distant Metastases
- •2.4 Specific Diagnostic Queries
- •2.4.1 Preoperative Imaging
- •2.4.2 Imaging Before Radiotherapy
- •2.5 Follow-Up
- •2.5.1 Findings After Surgery
- •2.5.2 Findings After Chemotherapy
- •2.5.3 Findings After Radiotherapy
- •2.5.4 Recurrent Cervical Cancer
- •2.6.1 Ultrasound
- •2.7.1 Metastasis
- •2.7.2 Malignant Melanoma
- •2.7.3 Lymphoma
- •2.8 Benign Lesions of the Cervix
- •2.8.1 Nabothian Cyst
- •2.8.2 Leiomyoma
- •2.8.3 Polyps
- •2.8.4 Rare Benign Tumors
- •2.8.5 Cervicitis
- •2.8.6 Endometriosis
- •2.8.7 Ectopic Cervical Pregnancy
- •References
- •Endometrial Cancer
- •1.1 Epidemiology
- •1.2 Pathology and Risk Factors
- •1.3 Symptoms and Diagnosis
- •2 Endometrial Cancer Staging
- •2.1 MR Protocol for Staging Endometrial Carcinoma
- •2.2.1 Stage I Disease
- •2.2.2 Stage II Disease
- •2.2.3 Stage III Disease
- •2.2.4 Stage IV Disease
- •4 Therapeutic Approaches
- •4.1 Surgery
- •4.2 Adjuvant Treatment
- •4.3 Fertility-Sparing Treatment
- •5.1 Treatment of Recurrence
- •6 Prognosis
- •References
- •Uterine Sarcomas
- •1 Epidemiology
- •2 Pathology
- •2.1 Smooth Muscle Tumours
- •2.2 Endometrial Stromal Tumours
- •3 Clinical Background
- •4 Staging
- •5 Imaging
- •5.1 Leiomyosarcoma
- •5.2.3 Undifferentiated Uterine Sarcoma
- •5.3 Adenosarcoma
- •6 Prognosis and Treatment
- •References
- •1.1 Anatomical Relationships
- •1.4 Pelvic Fluid
- •2 Developmental Anomalies
- •2.1 Congenital Abnormalities
- •2.2 Ovarian Maldescent
- •3 Ovarian Transposition
- •References
- •1 Introduction
- •4 Benign Adnexal Lesions
- •4.1.1 Physiological Ovarian Cysts: Follicular and Corpus Luteum Cysts
- •4.1.1.1 Imaging Findings in Physiological Ovarian Cysts
- •4.1.1.2 Differential Diagnosis
- •4.1.2 Paraovarian Cysts
- •4.1.2.1 Imaging Findings
- •4.1.2.2 Differential Diagnosis
- •4.1.3 Peritoneal Inclusion Cysts
- •4.1.3.1 Imaging Findings
- •4.1.3.2 Differential Diagnosis
- •4.1.4 Theca Lutein Cysts
- •4.1.4.1 Imaging Findings
- •4.1.4.2 Differential Diagnosis
- •4.1.5 Polycystic Ovary Syndrome
- •4.1.5.1 Imaging Findings
- •4.1.5.2 Differential Diagnosis
- •4.2.1 Cystadenoma
- •4.2.1.1 Imaging Findings
- •4.2.1.2 Differential Diagnosis
- •4.2.2 Cystadenofibroma
- •4.2.2.1 Imaging Features
- •4.2.3 Mature Teratoma
- •4.2.3.1 Mature Cystic Teratoma
- •Imaging Findings
- •Differential Diagnosis
- •4.2.3.2 Monodermal Teratoma
- •Imaging Findings
- •4.2.4 Benign Sex Cord-Stromal Tumors
- •4.2.4.1 Fibroma and Thecoma
- •Imaging Findings
- •4.2.4.2 Sclerosing Stromal Tumor
- •Imaging Findings
- •4.2.5 Brenner Tumors
- •4.2.5.1 Imaging Findings
- •4.2.5.2 Differential Diagnosis
- •5 Functioning Ovarian Tumors
- •References
- •1 Introduction
- •2.1 Context
- •2.2.2 Indications According to Simple Rules
- •References
- •CT and MRI in Ovarian Carcinoma
- •1 Introduction
- •2.1 Familial or Hereditary Ovarian Cancers
- •3 Screening for Ovarian Cancer
- •5 Tumor Markers
- •6 Clinical Presentation
- •7 Imaging of Ovarian Cancer
- •7.1.2 Peritoneal Carcinomatosis
- •7.1.3 Ascites
- •7.3 Staging of Ovarian Cancer
- •7.3.1 Staging by CT and MRI
- •Imaging Findings According to Tumor Stages
- •Value of Imaging
- •7.3.2 Prediction of Resectability
- •7.4 Tumor Types
- •7.4.1 Epithelial Ovarian Cancer
- •High-Grade Serous Ovarian Cancer
- •Low-Grade Serous Ovarian Cancer
- •Mucinous Epithelial Ovarian Cancer
- •Endometrioid Ovarian Carcinomas
- •Clear Cell Carcinomas
- •Imaging Findings of Epithelial Ovarian Cancers
- •Differential Diagnosis
- •Borderline Tumors
- •Imaging Findings
- •Differential Diagnosis
- •Recurrent Ovarian Cancer
- •Imaging Findings
- •Differential Diagnosis
- •Value of Imaging
- •Malignant Germ Cell Tumors
- •Dysgerminomas
- •Imaging Findings
- •Differential Diagnosis
- •Immature Teratomas
- •Imaging Findings
- •Malignant Transformation in Benign Teratoma
- •Imaging Findings
- •Differential Diagnosis
- •Sex-Cord Stromal Tumors
- •Granulosa Cell Tumors
- •Imaging Findings
- •Sertoli-Leydig Cell Tumor
- •Imaging Findings
- •Ovarian Lymphoma
- •Imaging Findings
- •Differential Diagnosis
- •7.4.3 Ovarian Metastases
- •Imaging Findings
- •Differential Diagnosis
- •7.5 Fallopian Tube Cancer
- •7.5.1 Imaging Findings
- •Differential Diagnosis
- •References
- •Endometriosis
- •1 Introduction
- •2.1 Sonography
- •3 MR Imaging Findings
- •References
- •Vagina and Vulva
- •1 Introduction
- •3.1 CT Appearance
- •3.2 MRI Protocol
- •3.3 MRI Appearance
- •4.1 Imperforate Hymen
- •4.2 Congenital Vaginal Septa
- •4.3 Vaginal Agenesis
- •5.1 Vaginal Cysts
- •5.1.1 Gardner Duct Cyst (Mesonephric Cyst)
- •5.1.2 Bartholin Gland Cyst
- •5.2.1 Vaginal Infections
- •5.2.1.1 Vulvar Infections
- •5.2.1.2 Vulvar Thrombophlebitis
- •5.3 Vulvar Trauma
- •5.4 Vaginal Fistula
- •5.5 Post-Radiation Changes
- •5.6 Benign Tumors
- •6.1 Vaginal Malignancies
- •6.1.1 Primary Vaginal Carcinoma
- •6.1.1.1 MRI Findings
- •6.1.1.2 Lymph Node Drainage
- •6.1.1.3 Recurrence and Complications
- •6.1.2 Non-squamous Cell Carcinomas of the Vagina
- •6.1.2.1 Adenocarcinoma
- •6.1.2.2 Melanoma
- •6.1.2.3 Sarcomas
- •6.1.2.4 Lymphoma
- •6.2 Vulvar Malignancies
- •6.2.1 Vulvar Carcinoma
- •6.2.2 Melanoma
- •6.2.3 Lymphoma
- •6.2.4 Aggressive Angiomyxoma of the Vulva
- •7 Vaginal Cuff Disease
- •7.1 MRI Findings
- •8 Foreign Bodies
- •References
- •Imaging of Lymph Nodes
- •1 Background
- •3 Technique
- •3.1.1 Intravenous Unspecific Contrast Agents
- •3.1.2 Intravenous Tissue-Specific Contrast Agents
- •References
- •1 Introduction
- •2.1.1 Imaging Findings
- •2.1.2 Differential Diagnosis
- •2.1.3 Value of Imaging
- •2.2 Pelvic Inflammatory
- •2.2.1 Imaging Findings
- •2.3 Hydropyosalpinx
- •2.3.1 Imaging Findings
- •2.3.2 Differential Diagnosis
- •2.4 Tubo-ovarian Abscess
- •2.4.1 Imaging Findings
- •2.4.2 Differential Diagnosis
- •2.4.3 Value of Imaging
- •2.5 Ovarian Torsion
- •2.5.1 Imaging Findings
- •2.5.2 Differential Diagnosis
- •2.5.3 Diagnostic Value
- •2.6 Ectopic Pregnancy
- •2.6.1 Imaging Findings
- •2.6.2 Differential Diagnosis
- •2.6.3 Value of Imaging
- •3.1 Pelvic Congestion Syndrome
- •3.1.1 Imaging Findings
- •3.1.2 Differential Diagnosis
- •3.1.3 Value of Imaging
- •3.2 Ovarian Vein Thrombosis
- •3.2.1 Imaging Findings
- •3.2.2 Differential Diagnosis
- •3.2.3 Value of Imaging
- •3.3 Appendicitis
- •3.3.1 Imaging Findings
- •3.3.2 Value of Imaging
- •3.4 Diverticulitis
- •3.4.1 Imaging Findings
- •3.4.2 Differential Diagnosis
- •3.4.3 Value of Imaging
- •3.5 Epiploic Appendagitis
- •3.5.1 Imaging Findings
- •3.5.2 Differential Diagnosis
- •3.5.3 Value of Imaging
- •3.6 Crohn’s Disease
- •3.6.1 Imaging Findings
- •3.6.2 Differential Diagnosis
- •3.6.3 Value of Imaging
- •3.7 Rectus Sheath Hematoma
- •3.7.1 Imaging Findings
- •3.7.2 Differential Diagnosis
- •3.7.3 Value of Imaging
- •References
- •MRI of the Pelvic Floor
- •1 Introduction
- •2 Imaging Techniques
- •3.1 Indications
- •3.2 Patient Preparation
- •3.3 Patient Instruction
- •3.4 Patient Positioning
- •3.5 Organ Opacification
- •3.6 Sequence Protocols
- •4 MR Image Analysis
- •4.1 Bony Pelvis
- •5 Typical Findings
- •5.1 Anterior Compartment
- •5.2 Middle Compartment
- •5.3 Posterior Compartment
- •5.4 Levator Ani Muscle
- •References
- •Evaluation of Infertility
- •1 Introduction
- •2 Imaging Techniques
- •2.1 Hysterosalpingography
- •2.1.1 Cycle Considerations
- •2.1.2 Technical Considerations
- •2.1.3 Side Effects and Complications
- •2.1.5 Pathological Findings
- •2.1.6 Limitations of HSG
- •2.2.1 Cycle Considerations
- •2.2.2 Technical Considerations
- •2.2.2.1 Normal and Abnormal Anatomy
- •2.2.3 Accuracy
- •2.2.4 Side Effects and Complications
- •2.2.5 Limitations of Sono-HSG
- •2.3 Magnetic Resonance Imaging
- •2.3.1 Indications
- •2.3.2 Technical Considerations
- •2.3.3 Limitations
- •3 Ovulatory Dysfunction
- •4 Pituitary Adenoma
- •5 Polycystic Ovarian Syndrome
- •7 Uterine Disorders
- •7.1 Müllerian Duct Anomalies
- •7.1.1 Class I: Hypoplasia or Agenesis
- •7.1.2 Class II: Unicornuate
- •7.1.3 Class III: Didelphys
- •7.1.4 Class IV: Bicornuate
- •7.1.5 Class V: Septate
- •7.1.6 Class VI: Arcuate
- •7.1.7 Class VII: Diethylstilbestrol Related
- •7.2 Adenomyosis
- •7.3 Leiomyoma
- •7.4 Endometriosis
- •References
- •MR Pelvimetry
- •1 Clinical Background
- •1.3.1 Diagnosis
- •1.3.2.1 Cephalopelvic Disproportion
- •1.3.4 Inadequate Progression of Labor due to Inefficient Contraction (“the Powers”)
- •2.2 Palpation of the Pelvis
- •3 MR Pelvimetry
- •3.2 MR Imaging Protocol
- •3.3 Image Analysis
- •3.4 Reference Values for MR Pelvimetry
- •5 Indications for Pelvimetry
- •References
- •MR Imaging of the Placenta
- •2 Imaging of the Placenta
- •3 MRI Protocol
- •4 Normal Appearance
- •4.1 Placenta Variants
- •5 Placenta Adhesive Disorders
- •6 Placenta Abruption
- •7 Solid Placental Masses
- •9 Future Directions
- •References
- •Erratum to: Endometrial Cancer
MRI of the Pelvic Floor
Rosemarie Forstner and Andreas Lienemann
Contents |
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7 Value of MRI Versus Conventional |
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Imaging Techniques\ |
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3 MRI Technique of the Pelvic Floor\ |
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Indications\ |
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Patient Preparation\ |
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Patient Instruction\ |
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Pelvic floor dysfunction comprises disorders |
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Patient Positioning\ |
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Organ Opacification\ |
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Sequence Protocols\ |
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4 MR Image Analysis\ |
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Bony Pelvis\ |
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4.2 Pelvic Floor Muscles and Ligaments\ |
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pelvic floor dysfunction that may signifi- |
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Middle Compartment\ |
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Levator Ani Muscle\ |
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6 MRI of the Pelvic Floor in Asymptomatic |
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diagnostic tool for treatment planning and for |
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tailoring the surgical approach in pelvic floor |
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This chapter reviews MRI for evaluation of |
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the pelvic floor. The first part focuses on |
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R. Forstner (*) |
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details of the examination technique, and pro- |
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Universitätsinsitut für Radiologie Landeskliniken |
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vides information to assess qualitatively and |
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Salzburg, Paracelsus Medical University, |
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quantitatively the pelvic floor. In the second |
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Müllner Hauptstr., 48, Salzburg, Austria |
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part typical imaging findings associated with |
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e-mail: R.Forstner@salk.at |
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pathologies within the three anatomical com- |
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A. Lienemann |
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Radiologie Mühleninsel, Mühlenstrasse 4, Landshut |
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Finally, strengths and limitations of MRI of |
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84028, Germany |
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the pelvic floor will be discussed. |
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DOI 10.1007/174_2017_53, © Springer International Publishing AG
Published Online: 19 April 2017
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Abbreviations
MRI\ |
Magnetic resonance imaging |
PCL\ |
Pubococcygeal line |
POP\ |
Pelvic organ prolapse |
US\ |
Ultrasonography |
WI\ |
Weighted images |
1\ Introduction
Pelvic floor dysfunction has become a major health care issue with the increasing ageing population. It is an umbrella term for different clinical disorders related to pelvic floor descent and pelvic organ prolapse, urinary and fecal incontinence, defecation disorders, or pelvic pain (Pannu et al. 2015). Pelvic floor dysfunction affects 30–50% of women, with approximately 10–20% of these becoming symptomatic and requiring surgery (Jundt et al. 2015). POP recurrence rates after surgery are high with a range between 30 and 70% (Tijdink et al. 2011). Although it may occur in young age, typically postmenopausal women suffer from pelvic floor dysfunction that may significantly impair the quality of life (Rogers and Fashokun 2016). Its etiology is multifactorial and associated with degradation of collagen, hormonal effects, obesity, multiparity, vaginal delivery, previous surgeries, constipation, muscle denervation, and menopause. But female gender, increasing age, and childbirths have been recognized as leading risk factors (Rogers and Fashokun 2016). Demographic developments in industrialized countries let expect the substantially increased need of imaging in patients with pelvic floor symptoms (Woodfield et al. 2010).
Among the imaging modalities MRI has emerged as an imaging technique to provide comprehensive information and has become an important diagnostic tool for treatment planning and for tailoring the surgical approach in pelvic floor pathologies (Pannu et al. 2015; El Sayed et al. 2016).
2\ Imaging Techniques
Imaging modalities to assess the pelvic floor comprise conventional fluoroscopic techniques, ultrasonography, and MRI. Fluoroscopic X-ray techniques include cystourethrography, defecography or evacuation or voiding proctography, and colpocystoproctography. The latter requires opacification of multiple organs such as rectum, vagina, and small bowel and instillation of contrast media into the bladder via a urinary bladder catheter (Kim 2011). This widely available technique is performed in physiological sitting position, but is limited with respect of radiation exposure and inability to directly visualize the pelvic floor (Flusberg et al. 2011).
Various approaches including transabdominal, transvaginal, endoanal, transperineal, and translabial sonography have been used to assess urinary or fecal incontinence. Wellknown advantages of this technique are short duration of exam, wide availability, and realtime imaging capabilities (Pannu et al. 2015). These, however, are outweighed by the small field of view, and its high operator dependence. Although its routine use is still limited, 3D and 4D US are emerging techniques to diagnose POP and are able to demonstrate pelvic musculature and fascias and otherwise difficult-to- assess mesh slings or implants (Dietz 2010). When performed by experts, good to excellent interobserver agreement can be achieved even in multicompartment ultrasound of the pelvic floor (Lone et al. 2016).
MRI has become the imaging method of choice to assess complex pelvic floor disorders, as it provides a comprehensive approach by combining static and dynamic MRI sequences (Maglinte et al. 2011). This technique has synonymously also been reported as dynamic MR, cine MR, MR defecography, MR proctography, or functional MR of the pelvic floor (Pannu et al. 2015; El Sayed et al. 2016). It was first introduced in 1991 by Yang et al. and Kruyt et al. They described movement of the bladder, vagina, and rectum in relation to the
MRI of the Pelvic Floor |
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pubococcygeal and symphysiosacral reference line in asymptomatic subjects and in patients. In 1993 Goodrich et al. recommended MRI for the preand postoperative evaluation of patients after pelvic floor surgery (Goodrich et al. 1993). Several consecutive publications showed at least equal results or its superiority compared to conventional colpocystoproctography and defecography (Gufler et al. 2004; Kelvin et al. 2000; Bump et al. 1996; Lienemann et al. 1996, 1997). Unfortunately for many years this technique showed inherent limitations in respect of standardization resulting in numerous variants of imaging techniques and protocols (El Sayed et al. 2016). A joint initiative of the ESUR and ESGAR pelvic floor working groups has overcome this problem and recommendations for the imaging technique and for reporting of pelvic floor disorders with MRI have been published in 2016 (El Sayed et al. 2016).
3\ MRI Technique of the Pelvic
Floor
3.1\ Indications
Pelvic floor dysfunction may manifest with symptoms related specifically to affected structures, e.g., with urinary symptoms (stress and urge incontinence, or obstructed voiding), with defecatory symptoms (constipation, fecal incontinence, difficult or incomplete defecation), as pelvic pain or as adverse effects on sexual function (Rogers and Fashokun 2016). Among these bowel symptoms, those typically arising from the posterior pelvic compartment are leading indications for MRI (El Sayed et al. 2016). A specialist survey enlisted in order of decreasing frequency rectal outlet obstruction, rectocele, recurrent pelvic organ prolapse, enterocele, and dyssynergetic pelvic floor syndrome as clinical symptoms best suited to be assessed by MRI (El Sayed et al. 2016). In the postoperative setting MRI may assist to elucidate postoperative complications and the causes
of failed POP repair by visualization of meshes, of relapsed POP, and of the integrity and movement of the pelvic floor muscles (Pannu et al. 2015; Alt et al. 2014).
3.2\ Patient Preparation
An overextended bladder may impair the diagnosis of pelvic floor dysfunction. This is why according to the recent recommendations the bladder should be emptied 2 h before the exam, which will result in a midfull bladder during the exam (El Sayed et al. 2016). Cleansing of the rectum prior to the exam is helpful, but joint recommendations do not exist. Devices, e.g., pessar rings or intravaginal diaphragms, have to be removed before the exam.
3.3\ Patient Instruction
Explaining the patient how to perform the required exercises is pivotal for a successful MRI study. Thus, optimally dedicated training for how to correctly perform the dynamic phases including straining, squeezing, and evacuation should precede the MR exam (El Sayed et al. 2016). As collaboration is pivotal, the patient has to be able to understand and follow the commands during the examination. Emptying of the rectum during the examination is required to assess the complex relationships in pelvic organ prolapse (Flusberg et al. 2011). This is why evacuation should be prolonged until complete defecation has been documented. Incomplete rectal evacuation results in a significantly lower sensitivity for the detection of pelvic floor defects by MRI compared to colpocystoproctography (Vanbeckevoort et al. 1999). If the patient is either too embarrassed to defecate inside the magnet or is unable to empty the rectum at all while lying supine, a triphasic approach may be performed with an additional post-toilet phase after the patient has evacuated in the bathroom (Kelvin et al. 2000).
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3.4\ Patient Positioning
In open-configuration MRI systems patients can be examined sitting on an MRI-compatible seat (Pannu et al. 2015; Lienemann et al. 1996). A physiological position for defecation cannot be achieved in close configuration systems where only horizontal positioning of the patient is feasible. In this case supine position is preferred to prone position, as it is more stable and convenient for the patient (Delemarre et al. 1994). Positioning with feed first will reduce claustrophobia. Furthermore, slight bending of the knees by a pillow underneath the knees and abduction of the hips will facilitate the process of defecation (Pannu et al. 2015; Bitti et al. 2014). Diapers and waterproof pads placed beneath the patient reliably prevent soiling of the table and help to improve the compliance (El Sayed et al. 2016; Lienemann et al. 1997; Healy et al. 1997a).
3.5\ Organ Opacification
On T2-weighted imaging fluid-filled structures like the bladder or small bowel loops exhibit high signal intensity. But other organs like the vagina, rectum, or anal canal show an intermediate to low signal intensity. To improve their visualization and their differentiation from adjacent tissues during the dynamic phases vaginal and rectal opacification by ultrasound gel is performed (Lienemann et al. 1997; Sprenger et al. 2000). Some authors also advocated the placement of thin catheters to outline the urethra and to fill the bladder with 60 mL of saline solution and contrast media (Kelvin et al. 2000; Hodroff et al. 2002). But it is important to be aware that the catheter might impede the movement of the urethra and a rectocele or enterocele may be masked by a full bladder or a cystocele blocking the genital hiatus.
Emptying the bladder 2 h before the MRI will result in a midfull bladder. Lack of rectal contrast may result in a suboptimal study (Pannu et al. 2015). This is why rectum opacification is performed to improve visualization of the anorectal junction and to diagnose rectoceles. Instillation
of 120–250 cm3 of ultrasound gel improves also assessment of intususceptions and of rectal evacuation. A larger amount of gel is likely to facilitate the defecation (Lienemann et al. 1997). In the ESUR/ESGAR recommendations no agreement on opacification of the vagina was obtained (El Sayed et al. 2016). But opacification with 20 cm3 of ultrasound gel allows visualization of the entire vagina and especially of the posterior fornix and its posterior vaginal wall (Lienemann et al. 1997). In addition, during Valsalva maneuver the gel in the vagina is emptied passively and thus the movement of the organ itself is not impeded (Hodroff et al. 2002).
3.6\ Sequence Protocols
Technical prerequisites include midto high-field MR systems, surface array coils, and upright or supine position of the patient (Pannu et al. 2015; El Sayed et al. 2016; Fielding et al. 1998; Fielding 2003; Lienemann 1998). Pivotal in MR imaging of pelvic floor disorders is the acquisition of both static and dynamic imaging techniques. Static images provide multiplanar high spatial resolution of the pelvic floor anatomy, particularly the muscles and ligamentous structures (El Sayed et al. 2016; Lienemann et al. 1997; Delemarre et al. 1994). Integrity of the anal sphincter complex, position and morphology of the pelvic organs, and perivaginal space can also be assessed (Pannu et al. 2015; Fielding 2003). Furthermore, incidental findings (e.g., Bartholini, Gartner or ovarian cysts, or uterine leiomyomas) may be seen (Lienemann 1998).
Dynamic MRIs are performed at rest, squeezing, under maximal stress of the pelvic floor, and during defecation and displayed in cine mode (Fig. 1). Thus pelvic floor mobility, integrity of the pelvic floor or pelvic floor weakness, and organ prolapses are best visualized (El Sayed et al. 2016).
T2W imaging of the pelvic is performed at rest in three planes. This is followed by a dynamic acquisition in midsagittal plane at rest during squeezing, maximum straining, and evacuation of the rectal gel. Technical details of the MRI
MRI of the Pelvic Floor |
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a |
b |
c |
d |
Fig. 1 Maneuvers of the dynamic series at rest (a), squeeze (b), straining (c), and defecation (d)
protocol as suggested by the ESUR/ESGAR recommendations are summarized in Table 1.
For the dynamic studies the midsagittal plane through the pelvis is the preferred slice orientation. It provides an excellent overview of all rel-
evant organs within the different compartments of the pelvis and of the bony frame (Lienemann 1998) (Figs. 2, 3, and 4). This view is similar to conventional cystography or evacuation proctography. Owing to the complexity of the pelvic
Table 1 Recommended MR imaging protocol by ESUR/ESGAR
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Numbers of |
Plane |
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Sequence |
Technique |
TE(ms) |
TR (ms) |
mm |
FOV (mm) |
Matrix |
Plane/angulation |
slices |
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Static MRI sequences 2D MRI |
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Sag. |
T2WI |
Turbo/fast spin |
77–132 |
500–4210 |
4 |
200–300 |
256–448 |
Midsagittal |
23 |
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echo |
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Trans. |
T2WI |
Turbo/fast spin |
88–132 |
500–7265 |
4 |
200–300 |
256–512 |
Perpendicular to |
25 |
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echo |
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urethra |
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Cor. |
T2WI |
Turbo/fast spin |
80–132 |
500–7265 |
4 |
200–260 |
256–512 |
Parallel to urethra |
26 |
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echo |
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Dynamic MRI sequences |
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Squeezing |
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Sag. |
T2WI |
GEa |
1.27–1.88 |
3.3–397.4 |
8 |
250–310 |
126–280 |
Midsagittal |
1 or 3 |
Straining |
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Sag. |
T2WI |
GEa |
1.27–1.88 |
3.3–397.4 |
8 |
250–310 |
126–280 |
Midsagittal |
1 or 3 |
Optional |
|
Trans. |
T2WI |
GEa |
1.6–80 |
5,0–1,200 |
5 or 6 |
250–310 |
126–280 |
Perpendicular to the |
5 |
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urethra |
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Optional |
|
Cor. |
T2WI |
GEa |
1.6 |
5 |
5 or 6 |
300 |
256 |
Parallel to the urethra |
5 |
MR-Defecography |
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Sag. |
T2WI |
GEa |
1.27–1.88 |
3.3–397.4 |
8 |
250–310 |
168–280 |
Midsagittal |
1 or 3 |
Optional |
|
Cor. |
T2WI |
GEa |
1.27–1.6 |
5–397 |
4 or 8 |
257–350 |
154–256 |
Parallel to anorectum |
5 |
With permission from El Sayed et al. (2016) aGE, ultrafast GE and balanced GE
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Lienemann .A and Forstner .R
MRI of the Pelvic Floor |
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a |
b |
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d |
Fig. 2 Combined organ descent in a 40-year-old primiparous woman with stool outlet obstruction. T2-weighted functional MR images of the pelvis (a–c midsagittal; d transversal) obtained with the patient at rest (a) and during straining (b–d). (a) Normal position of the bladder (B), vagina (V), and uterus (U) above the pubococcygeal reference line (white line). The rectum (R) shows no anterior bulging. Vagina and rectum are filled with sonography gel. (b) During the first period of straining the anterior rectal wall is protruding in an anterior direction forming a deep rectocele (arrows). The bladder (B) and the uterus (U) descend only slightly. (c) After repeated straining and
defecation now the rectum (R) and the rectocele (arrow) are emptied. Therefore, given more space to slide into the genital hiatus, a large cystocele (B) and a descensus of the uterus (U) far below the PC line occur causing a compression of the rectal lumen. Note the relaxed levator ani muscle with a nearly vertical orientation. (d) In the axial plane (level of the pubic symphysis) a ballooning of the levator ani muscle (arrows) resulting from muscular weakness can be seen. The descending bladder (B), lower parts of the uterus (U), and the rectum (asterisk) are located between the two sides of the puborectal muscle
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a |
b |
Fig. 3 Multiparous 71-year-old woman with defecation disorder. Midsagittal T2-weighted MR images of the pelvis obtained with the patient straining repeatedly. (a) During the first straining episode the well-gel-filled rectum (R) shows an extensive bulging of the rectal wall in the anterior-perineal as well as in the posterior direction (white arrows). This anterior and posterior rectocele stabilizes the position of both the bladder (B) and the vaginal vault (asterisk), which stay at the level of the PC line.
Fig. 4 A 69-year-old female with a partial prolapse of the posterior vaginal wall during clinical examination. Midsagittal T2-weighted MR images obtained with the patient straining. A huge bulging of the anterior rectal wall in an anterior direction occurs. The depth of the rectocele can be measured as the distance between the tip of the rectocele (double arrow) and a parallel line along the anal canal (black line). The bladder (B) and the uterus (U) descend only slightly
Additionally, a thickening of the rectal mucosa (black arrows) is depicted marking a beginning intussusception. (b) After incomplete emptying of the rectocele and rectum (R) a large enterocele (E) has developed with mesenterial fatty tissue sliding down into the rectovaginal space. The sonography gel in the vagina has been evacuated passively. These findings are accompanied by a small cystocele with funneling of the urethra (arrow) and a vaginal vault descent (asterisk)