Corticotropin- and thyrotropin-secreting pituitary microadenomas: detection by dynamic magnetic resonance imaging.

Hormone-secreting pituitary microadenomas are often not visible on magnetic resonance imaging (MRI). Diagnosis requires confirmatory endocrine test results and often an invasive procedure, inferior petrosal sinus sampling (IPSS). Improved pituitary imaging may eliminate the need for IPSS in some patients, as shown in the 2 women in this report. The first patient with hirsutism, weight gain, and hypertension had intermittent elevations of urinary free cortisol, abnormal results on a low-dose dexamethasone suppression test, and positive results on a dexamethasone-suppressed ovine corticotropin-releasing hormone test (corticotropin, increase of 122%; cortisol, increase of 118%). Gadolinium-enhanced MRI showed no focal lesion, but dynamic MRI (sequential images beginning immediately after contrast injection) revealed a right-sided 5-mm microadenoma, confirmed by transsphenoidal surgery. The second patient had a goiter, anxiety, increased free thyroxine and triiodothyronine levels, and a normal thyrotropin value with no response to thyrotropin-releasing hormone. Magnetic resonance imaging showed no lesion, but dynamic MRI detected an 8-mm microadenoma. Although about 8% to 10% of healthy persons have incidental pituitary lesions that are 3 mm or larger on MRI, identification of a distinct lesion and positive results on a dexamethasone-suppressed ovine corticotropin-releasing hormone test should decrease the probability of a false-positive result on an imaging study. We recommend that dynamic MRI be performed in any patient with a suspected microadenoma, before IPSS is performed.

In vitro evaluation of MR hypointensity in Aspergillus colonies.

PURPOSE: To demonstrate that paramagnetic elements in fungal colonies can cause hypointensity in MR images. METHODS: Aspergillus fumigatus grown in vitro was imaged with CT and MR at the time of initial inoculation and 5 days later. CT and MR images, T2 values, scanning electron microscopy, energy-dispersive analysis, and furnace atomic absorption spectrometry were performed. RESULTS: After 5 days of growth, MR images of A fumigatus revealed curvilinear hypointensities on T2-weighted images corresponding to the fungal growth. Gradient-echo images revealed two distinct components of hypointensity with different calculated T2 values. Phase-angle-difference images revealed a phase shift characteristic of magnetic-susceptibility paramagnetic effects, which corresponded to the hypointense regions on gradient-echo images. Energy-dispersive analysis and furnace atomic absorption spectrometry confirmed the presence of paramagnetic elements. CONCLUSION: It was shown that in vitro A fumigatus concentrates metal elements contained within the nutrient broth. These focal collections of calculated T2 values are caused at least partly by magnetic susceptibility effects.

Pancreatic metastasis from Ewing's sarcoma.

A 26-year-old man with Ewing's sarcoma of the femur was found to have a solitary visceral metastatic focus in the pancreas. This very unusual occurrence and the topic of metastases to the pancreas in general are discussed.

Sensitivity of hysterosalpingography after tubal surgery.

Hysterosalpingography (HSG) to assess tubal patency in the postoperative evaluation of the infertile patient has been well described. However, the sensitivity and specificity of HSG after tubal surgery has not been reported. We correlated HSG and laparoscopic findings in 25 patients who had tubal surgery (microsurgical tubal reanastomoses [11] and distal salpingostomies [14]). HSG provided a more reliable means of assessing tubal patency (sensitivity and specificity of 96% and 61% respectively) than in detecting pelvic adhesive disease (PAD) (sensitivity and specificity of 12% and 75% respectively) regardless of tubal surgical procedure. HSG was associated with a high false negative rate (60%) due primarily to the inability to detect PAD. Complete agreement between HSG and laparoscopy was noted in only 15% of cases. These data suggest that HSG is a sensitive means to determine tubal patency, but was not sufficiently sensitive or specific to detect PAD after tubal surgery. These limitations should be noted in the interpretation of HSG in any infertile patient with a history of tubal surgery, and severely limits the application of HSG to the management of the post-operative infertile patient.

PIP: Researchers analyzed data on 25 women who underwent either tubal reanastomosis or distal salpingostomy at least 12 months earlier and came to the Tripler Army Medical Center in Honolulu, Hawaii, for hysterosalpingography (HSG) to compare HSD findings with those of laparoscopy, thereby determining HSG's sensitivity and specificity after tubal repair. They were only able to evaluate 42 tubes, since 2 patients had severe pelvic adhesive disease. HSG was more reliable in determining tubal patency (sensitivity of 96% and specificity of 61%) than in detecting pelvic adhesive disease (12% and 75%, respectively). HSG and laparoscopy findings agreed in just 15% of cases. HSG's inability to detect pelvic adhesions was responsible for this low agreement rate. Specifically, HSG found adhesions in only 6% of patients compared to 65% for laparoscopy (false negative rate = 60%). The adhesions completely covered all pelvic structures in 8% of cases at the same frequency for both reanastomosis and salpingostomy, thereby making it impossible to evaluate the anatomy. Further, HSG did not detect other pelvic pathologies (mild endometriosis, uterine fibroids, and ampullary fistulae) in 10% of cases. These findings suggest that HSG is sensitive and specific enough to assess tubal patency following reanastomosis, but is basically not specific enough to do so after distal salpingostomy. Therefore, clinicians should be aware of HSG's limitations when interpreting any HSG findings in infertile patients who had tubal surgery. Further, it limits their ability to manage postoperative infertile patients.

Inverted papilloma: evaluation with MR imaging.

The authors examined the magnetic resonance (MR) appearance of inverted papillomas to determine if this histologically benign lesion could be distinguished from malignancies of the sinonasal cavity. MR images in 10 patients with histologically proved inverted papilloma were retrospectively reviewed. The signal intensity of inverted papillomas on short repetition time (TR) images was iso- to slightly hypertintense to muscle in all 10 patients. Inverted papillomas had intermediate signal intensity on the long TR/echo time (TE) images. The tumors were iso- or slightly hypointense to fat on long TR/short TE images. In the seven patients who received gadopentetate dimeglumine, all inverted papillomas showed solid inhomogeneous enhancement. A review of eight sinonasal malignancies showed no distinctive signal intensity or enhancement characteristics to help differentiate inverted papillomas from various malignant tumors. The authors conclude that there is no signature MR appearance for the benign inverted papilloma. The main utility of MR imaging is in defining the extent of the lesion.