You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A patient presents with a solitary pulmonary nodule (SPN) on X-ray. The best investigation to come to diagnosis would be – and explain in detail?
"Thoracotomy with resection represents the most direct and definitive means of diagnosis (and treatment) of solitary pulmonary nodule"."Thoracotomy is the most definitive method for determining the diagnosis in patients with SNPs".

However, a thoracotomy is associated with significant morbidity, complications and mortality. Therefore, CT guided a transthoracic biopsy is the invasive diagnostic procedure of choice.

Note -If the question would have been about the next investigation of choice (instead of best investigation), then the answer will be CT scan.