Susceptibility Perturbation MRI Maps Tumor Infiltration into Mesorectal Lymph Nodes.

Noninvasive characterization of lymph node involvement in cancer is an enduring onerous challenge. In rectal cancer, pathologic lymph node status constitutes the most important determinant of local recurrence and overall survival, and patients with involved lymph nodes may benefit from preoperative chemo and/or radiotherapy. However, knowledge of lymph node status before surgery is currently hampered by limited imaging accuracy. Here, we introduce Susceptibility-Perturbation MRI (SPI) as a novel source of contrast to map malignant infiltration into mesorectal lymph nodes. SPI involves multigradient echo (MGE) signal decays presenting a nonmonoexponential nature, which we show is sensitive to the underlying microstructure via susceptibility perturbations. Using numerical simulations, we predicted that the large cell morphology and the high cellularity of tumor within affected mesorectal lymph nodes would induce signature SPI decays. We validated this prediction in mesorectal lymph nodes excised from total mesorectal excision specimens of patients with rectal cancer using ultrahigh field (16.4 T) MRI. SPI signals distinguished benign from malignant nodal tissue, both qualitatively and quantitatively, and our histologic analyses confirmed cellularity and cell size were the likely underlying sources for the differences observed. SPI was then adapted to a clinical 1.5 T scanner, added to patients' staging protocol, and compared with conventional assessment by two expert radiologists. Nonmonoexponential decays, similar to those observed in the ex vivo study, were demonstrated, and SPI classified lymph nodes more accurately than standard high-resolution T2-weighted imaging assessment. These findings suggest this simple, yet highly informative, method can improve rectal cancer patient selection for neoadjuvant therapy. SIGNIFICANCE: These findings introduce an MRI methodology tailored to detect magnetic susceptibility perturbations induced by subtle alterations in tissue microstructure.

Duodeno-colic fistula as a rare presentation of lung cancer - surgical treatment of a stage IV oligometastatic lung disease.

INTRODUCTION: Rare adenosquamous carcinomas have no defined standard approach given their low incidence. They present with nonspecific imaging characteristics and are described as having worse prognosis than other lung malignancies, with greater likelihood of local invasion and early metastasis. PRESENTATION OF CASE: Male caucasian patient, 43 years, 26 pack-year smoking history, presented with watery diarrhea, early emesis and loss of 25% body weight (20kg) in four weeks. Colonoscopy identified a left colonic mass. Abdominal CT/ultrasound showed a large fistulous lesion between the 4th portion of the duodenum and left colon. CT showed a solid mass in the right upper lung lobe. Endoscopy and transthoracic biopsy were inconclusive. En bloc D3 and D4 duodenectomy, proximal enterectomy and left hemicolectomy were performed, with inconclusive histology of the specimen. Three months later, a right upper lung lobectomy with lymphadenectomy was performed, revealing an adenosquamous carcinoma of lung origin, R0, staged as pT2pN0pM1b. Six months later, a single dural metastasis in the left cerebellopontine angle was detected and resected, with subsequent holocranial radiotherapy and systemic adjuvant chemotherapy. Patient is currently with 18 months follow-up, in good general health and with no evidence of recurrent disease. DISCUSSION: There are no specific guidelines to treat oligometastatic adenosquamous lung carcinoma. Our approach was abdominal surgery as a life-saving procedure and, months later, oncological resection of primary lung tumor and metachronous metastasis to the brain. CONCLUSION: A systematic, patient-oriented, patient-shared, multidisciplinary approach is particularly relevant when dealing with atypical presentations of rare diseases in young patients.