Determination of adequate bony resection margins in inflammatory jaw pathologies using SPECT-CT in primary mandibular reconstruction with virtually planned vascularized bone flaps

Abstract

Objectives: In advanced stages of osteoradionecrosis, medication-related osteonecrosis of the jaw, and osteomyelitis, a resection of sections of the mandible may be unavoidable. The determination of adequate bony resection margins is a fundamental problem because bony resection margins cannot be secured intraoperatively. Single-photon emission computed tomography (SPECT-CT) is more accurate than conventional imaging techniques in detecting inflammatory jaw pathologies. The clinical benefit for virtual planning of mandibular resection and primary reconstruction with vascularized bone flaps has not yet been investigated. This study aimed to evaluate the determination of adequate bony resection margins using SPECT computed tomography (SPECT-CT) for primary microvascular reconstruction of the mandible in inflammatory jaw pathologies.

Materials and methods: The cases of 20 patients with inflammatory jaw pathologies who underwent primary microvascular mandibular reconstruction after the bony resection margins were determined with SPECT-CT were retrospectively analyzed. The bony resection margins determined by SPECT-CT were histologically validated. The sensitivity was calculated as the detection rate and the positive predictive value as the diagnostic precision. Radiological ossification of the vascularized bone flaps with the mandibular stumps was assessed at least 6 months after reconstruction. The clinical course was followed for 12 months.

Results: The determination of adequate bony resection margins with SPECT-CT yielded a sensitivity of 100% and a positive predictive value of 94.7%. Of all the bony resection margins, 97.4% were radiologically sufficiently ossified with the vascularized bone flap and showed no complications in the clinical course.

Conclusions: SPECT-CT could increase the probability of determining adequate bony resection margins.

Clinical relevance: SPECT-CT could have a beneficial clinical impact in the context of primary microvascular bony reconstruction in inflammatory jaw pathologies.

Keywords: Inflammatory jaw pathologies; Mandible reconstruction; Medication-related osteonecrosis of the jaw; Osteomyelitis; Osteoradionecrosis; SPECT-CT; Vascularized bone flaps.

Fig. 1

Orthopantomogram (OPG) at the initial presentation of a 53-year-old male patient with extensive osteoradionecrosis (ORN) in the mandible

Fig. 2

Determination of the right-sided (a, c, e) and left-sided (b, d, f) bony resection margins using low-dose computed tomography (CT) scans (a, b) and single-photon emission computed tomography (SPECT) scans (c, d). The osteotomy planes were defined at 2 mm away from abnormal tracer accumulation in SPECT-CT. Virtual planning of primary mandibular reconstruction (e, f) with a vascularized fibula flap with three segments (blue)

Fig. 3

Histological analysis of patient case no. 11 (64-year-old male patient with osteoradionecrosis [ORN] of the right and left mandible). The resection margins determined by SPECT-CT showed no histological signs of necrosis or acute inflammation on the right side. Despite histologic evidence of chronic active OM at the resection margin of the left mandible, ossification was sufficient, and no postoperative complications occurred at the junction between the resection margin of the left mandible and the vascularized bone flap. Two HE-stained transverse sections of the mandibular bone (a and b) with varying degrees of necrosis, fibrosis, and inflammation, evaluated according to the HOES-grading system; c) Selected area of vital bone with smooth contours, preserved nuclear staining of osteocytes, and fatty bone marrow spaces without significant necrosis, inflammation, or fibrosis (HOES: A1-0, A2-0, A3-0, C1-0, C2-0 = no indication of osteomyelitis); d) Selected area of bone with smooth contours, but focal absence of vital osteocytes next to marrow spaces with focal replacement of fatty tissue by initially fibrotic, edematous stroma with partial infiltration by lymphocytes, plasma cells, and single neutrophilic granulocytes (HOES: A1-1, A2-0, A3-1, C1-1, C2-2 = signs of subsided, chronic osteomyelitis); e) Selected area of necrotic bone with fragmentation, raggedly contoured bone with complete loss of vital osteocytes next to diffusely necrotic marrow spaces with fibrin and dense infiltration by neutrophilic granulocytes (HOES: A1-3, A2-3, A3-3, C1-0, C2-0 = signs of an acute osteomyelitis)

Fig. 4

Assessment of the ossification between the vascularized fibula flap segments and the mandibular bone stumps at the right-sided (a, c) and left-sided (b, d) resection margins (white arrows) before (a, b) and after (c, d) removal of osteosynthesis material