Nuclear Medicine & Radiation Therapy

Now it is more than 30 years since we are using the Bosniak classification for cystic renal masses, which represents the scale for cancer probability using imaging features. First, we used ultrasound, then CT then MRI for characterization.

Many studies were conducted try to characterize the lesions using the ADC values trying to reach solid values for characterization and subgrouping which we can use especially for indeterminate lesions and for benign lesions which are radiologically characterized as Bosniak III and IV and underwent unnecessary nephrectomies.

Objectives: Retrospective evaluation the efficiency of DWI and ADC values in characterization of benign, indeterminate, and malignant renal masses using 3T MRI.
Results: We found the ADC values of the benign cysts are significantly higher than malignant cysts (3.03 versus 2.35 10 mm/s), Median, P=0.0001 with sensitivity and specificity 84% and 92%, however still no definite cut off values for indeterminate lesions.
Conclusion: MRI ADC values can be used for differentiation of benign and malignant lesions with high sensitivity and specificity however still no definite cut off values for radiologically indeterminate cystic renal masses.

Background: Currently the best intervention after injection of 99mTc-HDP is drinking plenty of fluid with no specific amount or time limit. The previous studies did show some but not significant improvement between image qualities of patients who drank water compared to those who did not drink. We aim to investigate if increased and more rapid fluid intake results in better image quality.
Methods: In this study, all patients who had a bone scintigram were questioned about how much fluid they had in the two hours between injection and imaging, and how much of that was taken in the first hour post injection The images were acquired two hour +/- 10min post intravenous injection of 99mTc-HDP using GE Infinia Hawkeye 4. The operator, equipment and radiopharmaceutical were the same for all studies and quality was assessed by measuring bone to soft tissue ratio using Xeleris 3 program.
Results: 146 adult patients with total of 156 images who had bone scan imaging at Auckland Radiology Group were assessed. These patients aged between 30 and 78 (median, 51), were mostly men (61%) and 10 (about 6.5%) had two bone scans.
The overall result, although a small change, was in favor of increasing fluid intake in the first hour which improved the bone to soft tissue ratio by an average of 2.5%. This was especially noticeable in patients who had two scans within few months of each other which could be compared, in this group nearly all the variables remain the same except the amount of fluid intake, this group had an average improvement of 9.65% (range, 2%-19.5%).
Conclusion: Rapid hydration post injection of 99mTc-HDP showed a small contribution on the quality of bone scan images however this together with increased likelihood of voiding earlier on post injection, which contributes to reducing radiation dose to the bladder wall, makes this method appealing to adopt for routine use.

Percutaneous Endoscopic Gastrostomy (PEG) is a common procedure done in patients with Carcinoma Esophagus whose nutritional status is compromised due to the primary disease and treatment related side effects. A rare and serious complication of this procedure is the metastatic spread of tumour from the esophagus to the gastrostomy site. We discuss a case of 70-year-old lady with Stage IVA (T4bN0M0) Squamous cell carcinoma esophagus who underwent PEG insertion prior to radical radiation treatment. 9 months later, she presented with a painful, ulceroproliferative growth at stomal site. It was histopathologically proven to be a metastasis from the primary. Palliative radiation with a dose of 30 Gy in 10 fractions by 3D conformal technique was delivered and good clinical response wasachieved. However preventive methods such as surgical gastrostomy tube insertion procedures and delaying the timing of insertion of PEG tube to after commencing definitive treatment might help to decrease the risk. Positron Emission Tomography-Computed Tomography (PET/CT) scan is an effective tool for early detection of PEG site metastasis.

Surgical treatment of the axilla in patients with breast cancer has changed with the arrival of the neoadjuvant systemic therapies (NST); the role of axillary lymph node dissection with the use of radiotracers, fluorescent particles, surgical clips and radioactive seeds appears to play a significant role following these systemic therapies. We present a novel dual technique (^99mTc-Nanocoll^® or ^99mTc-Lymphoseek^®) for sentinel lymph node biopsy (SLNB) and the use of magnetic seed (Magseed^®) for the achievement of more accurate and less invasive method to restaging the axilla after NST.

Prostate Cancer is one of the common cancers in the world. It could primarily disseminate to the bone and can lead to death. In order to address its life threatening distant metastasis it is important to diagnose it earlier for timely treatment. Bone metastasis is usually diagnosed deploying bone scan imaging. However interpretation of the bone scans is a tedious procedure for the physicians and often leads to misinterpretation either as overestimation or underestimation of the metastasis. To minimize the risk of misinterpretation, one of the accurate methods is quantitative analysis of the bone scans in order to ascertain, whether a metastatic lesion is present or not. There are several methods to-date which can be used to analyze the extent of such lesions. For example, quantitation of the bone scan using quantitation methods i.e. %BSI (Bone scan index), %PAB (Positive area on bone scans), EOD (extent of disease) and BLS (Bone lesion scoring). These methods are used for prognostication of survival and response to treatment on serial scans. The extent of fidelity of these all available quantitation methods is not clear when used altogether in a single baseline bone scan. Therefore, the aim of this study is to use all available bone scan quantitative parameters on a baseline bone scans and to compare them all. Moreover, an improved methodology is introduced by comparing the results with the individual methods reported in literature and with PSA levels.

141 patients with histopathologically proved prostate cancer were chosen to implement all the four quantitative parameters on individual baseline bone scans. After which, for the calculation of risk of progression or regression of disease and survival rate, 40 patients were chosen from the same dataset. A serial follow up scan was performed to calculate 2-years survival rate. The dataset was again analyzed using the same four bone scan quantitative parameters and the cut off were calculated as %BSI: 1, %PAB: 0.5, EOD: grade 0 & 1, grade 2, 3 & 4 and BLS: 5.

It was found out that the %PAB and %BSI methods are good prognostic indicator in baseline scans. Moreover the prostate cancer patients with the cut off %BSI >1, %PAB >0.5, BLS >5 and EOD with grade 2, 3 & 4 showed increased risk of disease progression and less survival.

Papillary thyroid carcinoma is the most common thyroid gland cancer. Among several subtypes, classical (CVPC) and follicular (FVPC) subtype are the most frequent. The most important tumor characteristics for therapy planning and outcome are size/presence of extra thyroid invasion, multicentricity, lymphatic, vascular and capsule invasion, spreading in local lymph nodes. Level of Thyroglobulin is indirect indicator of tissue remnant after surgery. Among 20 patients with CVPC and 33 with FVPC we found out that there is statistically important difference between these two subtypes of PC regarding T stadium, lymphatic and capsule invasion and spread in local lymph nodes of the neck. CVPC has these characteristics significantly more often than FVPC. The difference between these two subtypes is not statistically important regarding multicentricity, vascular invasion and the level of thyroglobulin.