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Essentials on Oncological Imaging: Postoperative Computed Tomography and Magnetic Resonance Imaging of Oral Tongue Cancer
Canadian Association of Radiologists Journal 69 (2018) 458e467 www.carjonline.org
Neuroradiology / Neuroradiologie
Essentials on Oncological Imaging: Postoperative Computed Tomography and Magnetic Resonance Imaging of Oral Tongue Cancer Akira Baba, MDa,*, Hiroya Ojiri, MD, PhDb, Koshi Ikeda, MD, PhDb, Hideomi Yamauchi, MD, PhDb, Nobuhiro Ogino, MD, PhDb, Yuki Seto, MDa, Yuko Kobashi, MD, PhDa, Shinji Yamazoe, MD, PhDa, Takuji Mogami, MD, PhDa a
Department of Radiology, Ichikawa General Hospital Tokyo Dental College, Sugano, Ichikawa-shi, Chiba, Japan b Department of Radiology, Jikei University School of Medicine, Nishi-Shimbashi, Minato-ku, Tokyo, Japan
Abstract The contribution of diagnostic imaging in evaluating the pre- and postoperative status of tongue cancer is essential. Interpretation of postoperative images is made difficult by deformation; therefore, it is necessary to know how surgical technique, biological reaction, postoperative anatomy, and local recurrence are reflected on the images. This study explains the postoperative imaging features of tongue cancer to help in the early detection of local recurrence and avoid inappropriate treatment. We review schematic drawings of representative surgical procedures for tongue carcinoma, variable radiological features in postoperative conditions with or without complications, and typical features of local failures and their mimics. This article clarifies the important tasks of radiologists and clinicians in the postoperative evaluation of tongue carcinoma. Resume L’imagerie diagnostique est determinante pour evaluer l’etat d’un cancer de la langue avant et apres une intervention. Comme la deformation de la langue rend l’interpretation des images postoperatoires difficile, il est essentiel de pouvoir distinguer les elements visuels associes a la technique chirurgicale, aux reactions biologiques et a la recurrence locale et de conna^ıtre l’apparence des structures anatomiques a la suite de l’intervention chirurgicale. La presente etude decrit les caracteristiques radiologiques postoperatoires du cancer de la langue. Elle vise a favoriser la detection precoce de recurrence locale et a eviter le recours a des traitements inappropries. Elle examine les schemas des interventions chirurgicales habituellement pratiquees chez les personnes atteintes de carcinomes de la langue, les caracteristiques radiologiques variables des etats postoperatoires avec ou sans complications ainsi que les caracteristiques habituelles de recurrence locale et les signes trompeurs. Ainsi, le present article jette la lumiere sur le travail essentiel des radiologistes et des cliniciens lorsqu’ils evaluent un carcinome de la langue ayant fait l’objet d’une intervention chirurgicale. Ó 2018 Canadian Association of Radiologists. All rights reserved. Key Words: Postoperative; Computed tomography; Magnetic resonance imaging; Complication; Recurrence
Computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly used in postoperative followup for tongue cancer. Often, tumour recurrence may not be clinically evident until the recurrence is large enough to be palpable. Imaging plays an important role in postsurgical surveillance to detect early recurrence as an adjunct to clinical follow-up. Post-treatment CT and MRI are useful to * Address for correspondence: Akira Baba, MD, Department of Radiology, Tokyo Dental College Ichikawa General Hospital, 5-11-13, Sugano, Ichikawa-shi, Chiba 272-8513, Japan. E-mail address: [email protected] (A. Baba).
confirm recurrence and to determine its extent; such information is necessary to determine the possibility of salvage therapy. Differentiating postoperative changes from tumour recurrence using imaging is challenging because of altered anatomy secondary to resection, flap reconstructions, and postsurgical scarring. Radiologists should be familiar with the characteristics of common post-treatment changes, surgical techniques, biological reactions, and postoperative complications to distinguish their characteristics from those of tumour recurrence. We review schematic drawings of representative surgical procedures for tongue carcinoma, variable radiological features in postoperative conditions
0846-5371/$ - see front matter Ó 2018 Canadian Association of Radiologists. All rights reserved. https://doi.org/10.1016/j.carj.2018.08.001
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with or without complications, and typical features of local failures and their mimics to help in the early detection of local recurrence and avoid inappropriate treatment. Representative Surgical Procedures for Tongue Carcinoma and Noncomplicated Postoperative Images Types of Glossectomy A glossectomy is the surgical removal of all or part of the tongue. The surgery may be a partial glossectomy (removal of part of the tongue) (Figures 1-4), hemiglossectomy (one side of the tongue is removed) (Figures 5 and 6), or subtotal/total glossectomy (removal of all or almost all of tongue) (Figures 7 and 8). Types of Mandibulectomy When a tumour directly abuts or invades the mandible, mandibular resection is necessary. Necessity and type of mandibulectomy depend on the presence and degree of mandibular invasion [1]. Marginal mandibulectomy is a resection of part of the mandible, which leaves the mandibular arch intact (Figures 9 and 10). Segmental
Figure 2. Status of post partial glossectomy without myocutaneous flap reconstruction. Focal loss of tissue plane and soft tissue fullness along postoperative right lateral border of the tongue (arrows) on contrastenhanced computed tomography.
mandibulectomy describes the resection of a segment of the mandible with interruption of its continuity (Figures 11 and 12). Imaging of Noncomplicated Postoperative Conditions Typically, a loss of tissue planes and soft tissue fullness are seen along the lateral border of the tongue after a partial glossectomy (Figure 2). According to the extent of resection, the tip of the tongue is rotated to the resected side and sutured [2] (Figure 3). In subtotal/total glossectomies, the muscle flap presents as an area of mainly fat density and signal and fills a surgical defect (Figure 8). In most patients,
Figure 1. Surgical margins of partial glossectomy. Tumour (T), range of resection (within the dotted line).
Figure 3. Status of post partial glossectomy without myocutaneous flap reconstruction. Postoperative scar/fibrosis (arrows) is typically characterized by low signal intensity on T2-weighted images.
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Figure 4. Status of post partial glossectomy with myocutaneous flap reconstruction. Right lateral border of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography.
Figure 6. Status of post hemiglossectomy. Right half of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography.
by the 4th to 6th postoperative week, most hemorrhagic and edematous changes usually resolve [3]. Further healing will occur slowly over subsequent months, but a resolution can be
prolonged if postoperative irradiation is given. In some patients, a stable postoperative appearance was not reached until 12-18 months after the completion of treatment [3].
Figure 5. Surgical margins of hemi-glossectomy. Tumour (T), range of resection (within the dotted line).
Figure 7. Surgical margins of subtotal/total glossectomy. Tumour (T), range of resection (within the dotted line).
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Figure 8. Status of post subtotal/total glossectomy. Most part of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography (A). An myocutaneous flap (F) presenting as an area mainly of fat signal filling the surgical defect on T1-weighted images (B).
Myocutaneous Flap According to the extent of resection, an myocutaneous (MC) flap is used to cover the tissue defect. Because the nerve supply to the free flap is surgically resected, it is not innervated. Further, because the flaps gradually lose bulk, the muscle component undergoes alteration of density on CT and signal change on MRI, and eventually atrophied muscles seem to be fatty [4e6] (Figures 4, 6, 8). The signal intensity usually remains isointense to normal muscle in T1-weighted MRI. In contrast, there are variable patterns of the muscular components in MC flaps in T2-weighted MRI [5,7]. As a
Figure 9. Marginal mandibulectomy. Resection of a part of mandible, while leaving the mandible arch intact.
result, a reliable predictor of flap failure is neither high signal intensity on T2-weighted MRI nor the presence or absence of enhancement of the muscular component [4,5]. Fatsaturation sequences can be invaluable in confirming the benign post-treatment nature of the soft tissue bulk because of the fatty component of some free flaps, which can appear quite marked at first glance [5]. Acute and Chronic Complications Treatment complications are much less frequent than tumour recurrences, but their diagnosis may be clinical. Most complications related to surgery occur in the early period after treatment and sometimes in the chronic phase.
Figure 10. Status of postmarginal mandibulectomy. Sharp surgical margin of mandible indicate postoperative status without tumour recurrence on bone window computed tomography.
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Figure 11. Segmental mandibulectomy. Resection of a segment of the mandible with interruption of its continuity.
Abscess, Fistula Infection is an acute postoperative complication with or without leakage at the anastomosis. An abscess is typically identified as a fluid-attenuation area with an enhancing rim [3] (Figure 13). A typical abscess after surgery does not extend over the range of operative field [8]. Sometimes, abscesses may be confused with large necrotic lymph nodes.
Figure 12. Status of post segmental mandibulectomy. Sharp surgical margin of mandible indicate postoperative status without tumor recurrence on bone window computed tomography.
Figure 13. Abscess. A fluid attenuation area with enhancing rim (arrows) is noted in the subcutaneous tissue of the left lateral neck on contrast-enhanced computed tomography.
Radiologists need to evaluate the extent and location of the abscess and fistula formation. Imaging may be required for the detection of fistula and to confirm its tract. Many fistulas will close spontaneously, but some may need re-intervention. Contrast-enhanced imaging is necessary to distinguish an abscess from fluid collection (just a seroma) and cellulitis [3,7].
Figure 14. Hematoma. Slightly high attenuation lesion (H) is noted in right submandibular space on noncontrast computed tomography.
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Figure 17. Lossening of mini-screw. A loosening of mini-screw is manifested by progressive bony resorption around it (arrow) on bone window computed tomography. Figure 15. Ranula/sialocele. A fluid attenuation area (R) in right side of the oral floor is considered as ranula/sialocele on contrast-enhanced computed tomography.
Hematoma After surgery, hematomas are sometimes detected along the surgical margin [9]. Acute hematomas, which are located adjacent the anastomosis, showed characteristic density and signal changes on CT and T1-and T2-weighted images owing to hemoglobin degradation (Figure 14). Hematomas usually resolve spontaneously, requiring no further treatment if they are without an active hemorrhage. Ranula/Sialocele
saliva from the secretory apparatus of the salivary glands and presents as local fluid collection in the floor of the mouth or submandibular space (Figure 15). Imaging is required to determine the site of parenchymal/ductal injury and the location of the lesion and its relationship with surrounding structures [6]. Serous Retention and Seroma After surgery, fluid collection without inflammation is sometimes seen as local fluid collection along the surgical margin (Figure 16) [9]. Such seromas usually resolve spontaneously, requiring no further treatment.
A ranula/sialocele is a pseudocyst associated with mucus extravasation, which depends on the disruption of the flow of
Figure 16. Postoperative serous retention. A fluid attenuation area (arrow) in right lateral margin of the oral tongue is detected on contrast-enhanced computed tomography.
Figure 18. Local recurrence as focal mass. A local recurrence is usually identified as a growing soft tissue mass (arrows) along the left lateral border of the tongue on contrast-enhanced computed tomography. Necrotic metastatic adenopathy (N) is noted in left level II.
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Figure 19. Local recurrence as focal mass. T2-weighted image (A) reveals an infiltrative tumor (arrows) of slightly high signal at left ventral surface of the tongue. The tumor moderately enhances (arrows) on postcontrast fat-suppressed T1-weighted image (B). Diffusion-weighted imaging (C) shows a bright signal of the tumor (arrows), compatible with local recurrence.
Loosening of Mini Screws Loosening of mini screws in cases of reconstruction with metallic plates and screws after segmental mandibulectomy is a relatively late complication, manifested by progressive bony resorption around the mini screws (Figure 17). Typical CT and MRI Features of Local Failure The detection of local recurrence is the most important purpose of postoperative imaging of tongue cancer. The role of imaging is to assess submucosal recurrence and tumour relapse in the deep tissue planes, which are not easily clinically assessed. A circumscribed, infiltrate mass with enhancement is a key to diagnosing recurrent tumours.
Although small recurrences usually show homogeneous enhancement, large recurrences tend to be necrotic. As for MRI, a recurrent tumour is typically represented by a localized, expansive mass showing intermediate signal intensity on T1-weighted images, slightly high intensity on T2-weighted images, and moderate enhancement on post Gd-DPTA T1-weighted images [2,5] (Figure 19, A and B). MRI had advantages in differentiation of tumours and scars. However, edema after irradiation can hide persisting tumours [2]. This edema, which is most marked 4-6 weeks after therapy, makes the detection of recurrent tumours difficult. T2-weighted and short-tau inversion recovery sequences are
Focal Enhancement Mass By CT, local recurrence is usually identified as a growing soft tissue mass along the surgical margin [2] (Figure 18).
Figure 20. Flap margin recurrence. A recurrent mass (within circle) are noted along the cranial aspect of the myocutaneous flap (F).
Figure 21. Flap margin recurrence. A recurrent mass (arrows) are noted along the ventral aspect of the myocutaneous flap (F).
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Figure 22. Irregularity of bony cutting margin. A local recurrence (arrow) is sometimes identified as growing soft tissue mass. (A) Contrast-enhanced computed tomography [CT]) with irregular bony resorption. (B) Bone window CT at cutting edge of the mandible. Normal bony cutting margin should be sharp.
useful to alert radiologists to potential local recurrence and to distinguish this from radiation fibrosis. Diffusion-weighted imaging and apparent diffusion coefficient are useful tools to differentiate tumour recurrence from normal posttreatment changes and detect local recurrence (Figure 19C) [4,10,11]. However, it must be noted there has been a significant chance of false positivity or negativity. Advanced imaging modulates as perfusion CT and dynamic susceptibility contrast perfusion-weighted MRI can also play roles in the differentiation of local recurrence from post-treatment changes [12,13].
21). Few recurrences occur within the musculocutaneous flap [17]. It is important to assess the margins of the flap, where local recurrence most commonly occurs.
Flap Margin Recurrence
Conditions Mimicking Local Recurrence
Local recurrence in patients who have undergone free flap reconstruction most commonly occurs in relation to the recipient flap bed near the anastomotic site between the flap and the tumour resection site [2,4,5,14e16] (Figures 20 and
Postoperative Granuloma, Vascularized Scar
Irregularity of Bony Cutting Margin Local recurrence is sometimes identified as a growing soft tissue density mass with irregular bony resorption at the cutting edge of the mandible [2] (Figure 22). The sharp cutting edge of the mandible should be maintained without irregular bone resorption.
Postoperative granuloma, vascularized scar is typically identified as a moderately enhancing soft tissue mass (arrow)
Figure 23. Postoperative granuloma/vascularized scar. Postoperative granuloma/vascularized scar is typically identified as a moderately enhancing soft tissue mass (arrow) seemingly stable for long on contrast-enhanced computed tomography. (A) Six weeks after surgery. (B) Sixteen months after surgery.
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tissue, whereas a recurrent tumour is usually expansive [2,5]. On MRI, a fibrous scar is typically characterized by a low signal intensity on T2-weighted images [2] (Figure 3). Diffusion-weighted imaging and apparent diffusion coefficient can be useful tools to differentiate between benign postoperative scars, granulomas, and recurrences. Osteoradionecrosis
Figure 24. Osteoradionecrosis. Radiation induced osteonecrosis of left mandible body show resorption and destructive change (arrows) on bone window computed tomography.
Patients with head and neck cancers commonly undergo radiotherapy. In this case, it is difficult to distinguish osteonecrosis by radiation therapy from recurrence along the margin of the mandibulectomy [2,5] (Figure 24). In the mandible, findings, such as the association with cortical defects away from the position of the original tumour, make the diagnosis of mandibular osteoradionecrosis more likely [4,9]. Anatomical Distortion
at the anastomosis of surgical flaps seemingly stable over a long period [2]. Scars occurring after surgery present, at an early stage, as soft tissue density areas with ill-defined margins and distinct enhancement on CT and MRI [2] (Figures 2 and 23). Sometimes this makes it difficult to distinguish scars from recurrence [4]. Surgical history is very helpful because a vascularized scar could be mistaken for an enhancing recurrent tumor [6]. It is impossible to differentiate it from local recurrence based only on a single study. It is important to compare to the baseline study and previous studies with an appropriate follow-up protocol. It may be helpful information that a scar with a relatively long period tends to cause retraction and distorts the surrounding
Denervation changes may be visualized in lingual muscles supplied by the hypoglossal nerve after surgery. Denervation of muscles is typically manifested by decreased attenuation (secondary to edema or fatty infiltration due to muscle atrophy) on a CT scan (Figure 25), signal alteration (typically increased intensity on a T2-weighted image), contrasted enhancement on MRI (in early stage), and swelling in the early stage and atrophy in the chronic stage [5,18]. Such asymmetry may be recognized as local failure by a novice [5].
Conclusion We present imaging features and schematic drawings of representative surgical procedures for tongue cancer, postoperative complications, and typical patterns of local failure to clarify the important tasks of radiologists under such conditions. References
Figure 25. Unilateral CN12 sacrifice. Fat density (arrow) of left hemi-tongue derived from left CN12 denervation is confirmed on contrast-enhanced computed tomography.
[1] Garcia MR, Passos UL, Ezzedine TA, et al. Postsurgical imaging of the oral cavity and oropharynx: what radiologists need to know. Radiographics 2015;35:804e18. [2] Lell M, Baum U, Greess H, et al. Head and neck tumors: imaging recurrent tumor and post-therapeutic changes with CT and MRI. Eur J Radiol 2000;33:239e47. [3] Som PM, Urken ML, Biller H, et al. Imaging the postoperative neck. Radiology 1993;87:593e603. [4] Hermans R. Posttreatment imaging in head and neck cancer. Eur J Radiol 2008;66:501e11. [5] Offiah C, Hall E. Post-treatment imaging appearances in head and neck cancer patients. Clin Radiol 2011;66:13e24. [6] Abdel Razek AAK, Mukherji SK. Imaging of posttreatment salivary gland tumors. Neuroimaging Clin N Am 2018;28:199e208. [7] Chong VF. Post treatment imaging in head and neck tumours. Cancer Imaging 2005;5:8e10.
Postoperative CT and MRI of oral tongue cancer / Canadian Association of Radiologists Journal 69 (2018) 458e467 [8] Holt GR, McManus K, Newman RK, et al. Computed tomography in the diagnosis of deep-neck infections. Arch Otolaryngol 1982;108: 693e6. [9] Saito N, Nadgir RN, Nakahira M, et al. Posttreatment CT and MR imaging in head and neck. Radiographics 2012;32:1261e82. [10] Connolly M, Srinivasan A. Diffusion-weighted imaging in head and neck cancer:technique, limitations, and applications. Magn Reson Imaging Clin N Am 2018;26:121e33. [11] Abdel Razek AA, Kandeel AY, Soliman N, et al. Role of diffusion-weighted echo-planar MR imaging in differentiation of residual or recurrent head and neck tumors and posttreatment changes. AJNR Am J Neuroradiol 2007;28:1146e52. [12] Razek AA, Tawfik AM, Elsorogy LG, et al. Perfusion CT of head and neck cancer. Eur J Radiol 2014;83:537e44. [13] Razek AA, Gaballa G, Ashamalla G, et al. Dynamic susceptibility contrast perfusion-weighted magnetic resonance imaging and diffusion-weighted magnetic resonance imaging in differentiating
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recurrent head and neck cancer from postradiation changes. J Comput Assist Tomogr 2015;39:849e54. Tomura N, Watanabe O, Hirano Y, et al. MR imaging of recurrent head and neck tumours following flap reconstructive surgery. Clin Radiol 2002;57:109e13. Hudgins PA, Burson JG, Gussack GS, et al. CT and MR appearance of recurrent malignant head and neck neoplasms after resection and flap reconstruction. AJNR Am J Neuroradiol 1994;15:1689e94. Hudgins PA. Flap reconstruction in the head and neck: expected appearance, complications, and recurrent disease. Eur J Radiol 2002; 44:130e8. Ohgi K, Kohno A, Itabashi K, et al. Head and neck reconstruction with pectoralis major myocutaneous flap: CT evaluation. J Comput Assist Tomogr 1990;14:286e90. Forgani R, Smoker WRK, Curtin HD. Pathology of the oral region. In: Som PM, Curtin HD, editors. Head and Neck Imaging. 5th ed. St. Louis: Mosby; 2011. p. 1643e748.
Neuroradiology / Neuroradiologie
Essentials on Oncological Imaging: Postoperative Computed Tomography and Magnetic Resonance Imaging of Oral Tongue Cancer Akira Baba, MDa,*, Hiroya Ojiri, MD, PhDb, Koshi Ikeda, MD, PhDb, Hideomi Yamauchi, MD, PhDb, Nobuhiro Ogino, MD, PhDb, Yuki Seto, MDa, Yuko Kobashi, MD, PhDa, Shinji Yamazoe, MD, PhDa, Takuji Mogami, MD, PhDa a
Department of Radiology, Ichikawa General Hospital Tokyo Dental College, Sugano, Ichikawa-shi, Chiba, Japan b Department of Radiology, Jikei University School of Medicine, Nishi-Shimbashi, Minato-ku, Tokyo, Japan
Abstract The contribution of diagnostic imaging in evaluating the pre- and postoperative status of tongue cancer is essential. Interpretation of postoperative images is made difficult by deformation; therefore, it is necessary to know how surgical technique, biological reaction, postoperative anatomy, and local recurrence are reflected on the images. This study explains the postoperative imaging features of tongue cancer to help in the early detection of local recurrence and avoid inappropriate treatment. We review schematic drawings of representative surgical procedures for tongue carcinoma, variable radiological features in postoperative conditions with or without complications, and typical features of local failures and their mimics. This article clarifies the important tasks of radiologists and clinicians in the postoperative evaluation of tongue carcinoma. Resume L’imagerie diagnostique est determinante pour evaluer l’etat d’un cancer de la langue avant et apres une intervention. Comme la deformation de la langue rend l’interpretation des images postoperatoires difficile, il est essentiel de pouvoir distinguer les elements visuels associes a la technique chirurgicale, aux reactions biologiques et a la recurrence locale et de conna^ıtre l’apparence des structures anatomiques a la suite de l’intervention chirurgicale. La presente etude decrit les caracteristiques radiologiques postoperatoires du cancer de la langue. Elle vise a favoriser la detection precoce de recurrence locale et a eviter le recours a des traitements inappropries. Elle examine les schemas des interventions chirurgicales habituellement pratiquees chez les personnes atteintes de carcinomes de la langue, les caracteristiques radiologiques variables des etats postoperatoires avec ou sans complications ainsi que les caracteristiques habituelles de recurrence locale et les signes trompeurs. Ainsi, le present article jette la lumiere sur le travail essentiel des radiologistes et des cliniciens lorsqu’ils evaluent un carcinome de la langue ayant fait l’objet d’une intervention chirurgicale. Ó 2018 Canadian Association of Radiologists. All rights reserved. Key Words: Postoperative; Computed tomography; Magnetic resonance imaging; Complication; Recurrence
Computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly used in postoperative followup for tongue cancer. Often, tumour recurrence may not be clinically evident until the recurrence is large enough to be palpable. Imaging plays an important role in postsurgical surveillance to detect early recurrence as an adjunct to clinical follow-up. Post-treatment CT and MRI are useful to * Address for correspondence: Akira Baba, MD, Department of Radiology, Tokyo Dental College Ichikawa General Hospital, 5-11-13, Sugano, Ichikawa-shi, Chiba 272-8513, Japan. E-mail address: [email protected] (A. Baba).
confirm recurrence and to determine its extent; such information is necessary to determine the possibility of salvage therapy. Differentiating postoperative changes from tumour recurrence using imaging is challenging because of altered anatomy secondary to resection, flap reconstructions, and postsurgical scarring. Radiologists should be familiar with the characteristics of common post-treatment changes, surgical techniques, biological reactions, and postoperative complications to distinguish their characteristics from those of tumour recurrence. We review schematic drawings of representative surgical procedures for tongue carcinoma, variable radiological features in postoperative conditions
0846-5371/$ - see front matter Ó 2018 Canadian Association of Radiologists. All rights reserved. https://doi.org/10.1016/j.carj.2018.08.001
Postoperative CT and MRI of oral tongue cancer / Canadian Association of Radiologists Journal 69 (2018) 458e467
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with or without complications, and typical features of local failures and their mimics to help in the early detection of local recurrence and avoid inappropriate treatment. Representative Surgical Procedures for Tongue Carcinoma and Noncomplicated Postoperative Images Types of Glossectomy A glossectomy is the surgical removal of all or part of the tongue. The surgery may be a partial glossectomy (removal of part of the tongue) (Figures 1-4), hemiglossectomy (one side of the tongue is removed) (Figures 5 and 6), or subtotal/total glossectomy (removal of all or almost all of tongue) (Figures 7 and 8). Types of Mandibulectomy When a tumour directly abuts or invades the mandible, mandibular resection is necessary. Necessity and type of mandibulectomy depend on the presence and degree of mandibular invasion [1]. Marginal mandibulectomy is a resection of part of the mandible, which leaves the mandibular arch intact (Figures 9 and 10). Segmental
Figure 2. Status of post partial glossectomy without myocutaneous flap reconstruction. Focal loss of tissue plane and soft tissue fullness along postoperative right lateral border of the tongue (arrows) on contrastenhanced computed tomography.
mandibulectomy describes the resection of a segment of the mandible with interruption of its continuity (Figures 11 and 12). Imaging of Noncomplicated Postoperative Conditions Typically, a loss of tissue planes and soft tissue fullness are seen along the lateral border of the tongue after a partial glossectomy (Figure 2). According to the extent of resection, the tip of the tongue is rotated to the resected side and sutured [2] (Figure 3). In subtotal/total glossectomies, the muscle flap presents as an area of mainly fat density and signal and fills a surgical defect (Figure 8). In most patients,
Figure 1. Surgical margins of partial glossectomy. Tumour (T), range of resection (within the dotted line).
Figure 3. Status of post partial glossectomy without myocutaneous flap reconstruction. Postoperative scar/fibrosis (arrows) is typically characterized by low signal intensity on T2-weighted images.
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Figure 4. Status of post partial glossectomy with myocutaneous flap reconstruction. Right lateral border of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography.
Figure 6. Status of post hemiglossectomy. Right half of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography.
by the 4th to 6th postoperative week, most hemorrhagic and edematous changes usually resolve [3]. Further healing will occur slowly over subsequent months, but a resolution can be
prolonged if postoperative irradiation is given. In some patients, a stable postoperative appearance was not reached until 12-18 months after the completion of treatment [3].
Figure 5. Surgical margins of hemi-glossectomy. Tumour (T), range of resection (within the dotted line).
Figure 7. Surgical margins of subtotal/total glossectomy. Tumour (T), range of resection (within the dotted line).
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Figure 8. Status of post subtotal/total glossectomy. Most part of oral tongue is resected and an myocutaneous flap (F) mainly of fat attenuation placed along the surgical on contrast-enhanced computed tomography (A). An myocutaneous flap (F) presenting as an area mainly of fat signal filling the surgical defect on T1-weighted images (B).
Myocutaneous Flap According to the extent of resection, an myocutaneous (MC) flap is used to cover the tissue defect. Because the nerve supply to the free flap is surgically resected, it is not innervated. Further, because the flaps gradually lose bulk, the muscle component undergoes alteration of density on CT and signal change on MRI, and eventually atrophied muscles seem to be fatty [4e6] (Figures 4, 6, 8). The signal intensity usually remains isointense to normal muscle in T1-weighted MRI. In contrast, there are variable patterns of the muscular components in MC flaps in T2-weighted MRI [5,7]. As a
Figure 9. Marginal mandibulectomy. Resection of a part of mandible, while leaving the mandible arch intact.
result, a reliable predictor of flap failure is neither high signal intensity on T2-weighted MRI nor the presence or absence of enhancement of the muscular component [4,5]. Fatsaturation sequences can be invaluable in confirming the benign post-treatment nature of the soft tissue bulk because of the fatty component of some free flaps, which can appear quite marked at first glance [5]. Acute and Chronic Complications Treatment complications are much less frequent than tumour recurrences, but their diagnosis may be clinical. Most complications related to surgery occur in the early period after treatment and sometimes in the chronic phase.
Figure 10. Status of postmarginal mandibulectomy. Sharp surgical margin of mandible indicate postoperative status without tumour recurrence on bone window computed tomography.
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Figure 11. Segmental mandibulectomy. Resection of a segment of the mandible with interruption of its continuity.
Abscess, Fistula Infection is an acute postoperative complication with or without leakage at the anastomosis. An abscess is typically identified as a fluid-attenuation area with an enhancing rim [3] (Figure 13). A typical abscess after surgery does not extend over the range of operative field [8]. Sometimes, abscesses may be confused with large necrotic lymph nodes.
Figure 12. Status of post segmental mandibulectomy. Sharp surgical margin of mandible indicate postoperative status without tumor recurrence on bone window computed tomography.
Figure 13. Abscess. A fluid attenuation area with enhancing rim (arrows) is noted in the subcutaneous tissue of the left lateral neck on contrast-enhanced computed tomography.
Radiologists need to evaluate the extent and location of the abscess and fistula formation. Imaging may be required for the detection of fistula and to confirm its tract. Many fistulas will close spontaneously, but some may need re-intervention. Contrast-enhanced imaging is necessary to distinguish an abscess from fluid collection (just a seroma) and cellulitis [3,7].
Figure 14. Hematoma. Slightly high attenuation lesion (H) is noted in right submandibular space on noncontrast computed tomography.
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Figure 17. Lossening of mini-screw. A loosening of mini-screw is manifested by progressive bony resorption around it (arrow) on bone window computed tomography. Figure 15. Ranula/sialocele. A fluid attenuation area (R) in right side of the oral floor is considered as ranula/sialocele on contrast-enhanced computed tomography.
Hematoma After surgery, hematomas are sometimes detected along the surgical margin [9]. Acute hematomas, which are located adjacent the anastomosis, showed characteristic density and signal changes on CT and T1-and T2-weighted images owing to hemoglobin degradation (Figure 14). Hematomas usually resolve spontaneously, requiring no further treatment if they are without an active hemorrhage. Ranula/Sialocele
saliva from the secretory apparatus of the salivary glands and presents as local fluid collection in the floor of the mouth or submandibular space (Figure 15). Imaging is required to determine the site of parenchymal/ductal injury and the location of the lesion and its relationship with surrounding structures [6]. Serous Retention and Seroma After surgery, fluid collection without inflammation is sometimes seen as local fluid collection along the surgical margin (Figure 16) [9]. Such seromas usually resolve spontaneously, requiring no further treatment.
A ranula/sialocele is a pseudocyst associated with mucus extravasation, which depends on the disruption of the flow of
Figure 16. Postoperative serous retention. A fluid attenuation area (arrow) in right lateral margin of the oral tongue is detected on contrast-enhanced computed tomography.
Figure 18. Local recurrence as focal mass. A local recurrence is usually identified as a growing soft tissue mass (arrows) along the left lateral border of the tongue on contrast-enhanced computed tomography. Necrotic metastatic adenopathy (N) is noted in left level II.
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Figure 19. Local recurrence as focal mass. T2-weighted image (A) reveals an infiltrative tumor (arrows) of slightly high signal at left ventral surface of the tongue. The tumor moderately enhances (arrows) on postcontrast fat-suppressed T1-weighted image (B). Diffusion-weighted imaging (C) shows a bright signal of the tumor (arrows), compatible with local recurrence.
Loosening of Mini Screws Loosening of mini screws in cases of reconstruction with metallic plates and screws after segmental mandibulectomy is a relatively late complication, manifested by progressive bony resorption around the mini screws (Figure 17). Typical CT and MRI Features of Local Failure The detection of local recurrence is the most important purpose of postoperative imaging of tongue cancer. The role of imaging is to assess submucosal recurrence and tumour relapse in the deep tissue planes, which are not easily clinically assessed. A circumscribed, infiltrate mass with enhancement is a key to diagnosing recurrent tumours.
Although small recurrences usually show homogeneous enhancement, large recurrences tend to be necrotic. As for MRI, a recurrent tumour is typically represented by a localized, expansive mass showing intermediate signal intensity on T1-weighted images, slightly high intensity on T2-weighted images, and moderate enhancement on post Gd-DPTA T1-weighted images [2,5] (Figure 19, A and B). MRI had advantages in differentiation of tumours and scars. However, edema after irradiation can hide persisting tumours [2]. This edema, which is most marked 4-6 weeks after therapy, makes the detection of recurrent tumours difficult. T2-weighted and short-tau inversion recovery sequences are
Focal Enhancement Mass By CT, local recurrence is usually identified as a growing soft tissue mass along the surgical margin [2] (Figure 18).
Figure 20. Flap margin recurrence. A recurrent mass (within circle) are noted along the cranial aspect of the myocutaneous flap (F).
Figure 21. Flap margin recurrence. A recurrent mass (arrows) are noted along the ventral aspect of the myocutaneous flap (F).
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Figure 22. Irregularity of bony cutting margin. A local recurrence (arrow) is sometimes identified as growing soft tissue mass. (A) Contrast-enhanced computed tomography [CT]) with irregular bony resorption. (B) Bone window CT at cutting edge of the mandible. Normal bony cutting margin should be sharp.
useful to alert radiologists to potential local recurrence and to distinguish this from radiation fibrosis. Diffusion-weighted imaging and apparent diffusion coefficient are useful tools to differentiate tumour recurrence from normal posttreatment changes and detect local recurrence (Figure 19C) [4,10,11]. However, it must be noted there has been a significant chance of false positivity or negativity. Advanced imaging modulates as perfusion CT and dynamic susceptibility contrast perfusion-weighted MRI can also play roles in the differentiation of local recurrence from post-treatment changes [12,13].
21). Few recurrences occur within the musculocutaneous flap [17]. It is important to assess the margins of the flap, where local recurrence most commonly occurs.
Flap Margin Recurrence
Conditions Mimicking Local Recurrence
Local recurrence in patients who have undergone free flap reconstruction most commonly occurs in relation to the recipient flap bed near the anastomotic site between the flap and the tumour resection site [2,4,5,14e16] (Figures 20 and
Postoperative Granuloma, Vascularized Scar
Irregularity of Bony Cutting Margin Local recurrence is sometimes identified as a growing soft tissue density mass with irregular bony resorption at the cutting edge of the mandible [2] (Figure 22). The sharp cutting edge of the mandible should be maintained without irregular bone resorption.
Postoperative granuloma, vascularized scar is typically identified as a moderately enhancing soft tissue mass (arrow)
Figure 23. Postoperative granuloma/vascularized scar. Postoperative granuloma/vascularized scar is typically identified as a moderately enhancing soft tissue mass (arrow) seemingly stable for long on contrast-enhanced computed tomography. (A) Six weeks after surgery. (B) Sixteen months after surgery.
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tissue, whereas a recurrent tumour is usually expansive [2,5]. On MRI, a fibrous scar is typically characterized by a low signal intensity on T2-weighted images [2] (Figure 3). Diffusion-weighted imaging and apparent diffusion coefficient can be useful tools to differentiate between benign postoperative scars, granulomas, and recurrences. Osteoradionecrosis
Figure 24. Osteoradionecrosis. Radiation induced osteonecrosis of left mandible body show resorption and destructive change (arrows) on bone window computed tomography.
Patients with head and neck cancers commonly undergo radiotherapy. In this case, it is difficult to distinguish osteonecrosis by radiation therapy from recurrence along the margin of the mandibulectomy [2,5] (Figure 24). In the mandible, findings, such as the association with cortical defects away from the position of the original tumour, make the diagnosis of mandibular osteoradionecrosis more likely [4,9]. Anatomical Distortion
at the anastomosis of surgical flaps seemingly stable over a long period [2]. Scars occurring after surgery present, at an early stage, as soft tissue density areas with ill-defined margins and distinct enhancement on CT and MRI [2] (Figures 2 and 23). Sometimes this makes it difficult to distinguish scars from recurrence [4]. Surgical history is very helpful because a vascularized scar could be mistaken for an enhancing recurrent tumor [6]. It is impossible to differentiate it from local recurrence based only on a single study. It is important to compare to the baseline study and previous studies with an appropriate follow-up protocol. It may be helpful information that a scar with a relatively long period tends to cause retraction and distorts the surrounding
Denervation changes may be visualized in lingual muscles supplied by the hypoglossal nerve after surgery. Denervation of muscles is typically manifested by decreased attenuation (secondary to edema or fatty infiltration due to muscle atrophy) on a CT scan (Figure 25), signal alteration (typically increased intensity on a T2-weighted image), contrasted enhancement on MRI (in early stage), and swelling in the early stage and atrophy in the chronic stage [5,18]. Such asymmetry may be recognized as local failure by a novice [5].
Conclusion We present imaging features and schematic drawings of representative surgical procedures for tongue cancer, postoperative complications, and typical patterns of local failure to clarify the important tasks of radiologists under such conditions. References
Figure 25. Unilateral CN12 sacrifice. Fat density (arrow) of left hemi-tongue derived from left CN12 denervation is confirmed on contrast-enhanced computed tomography.
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